Figs 2.20a and b: (a) Normal arterial supply of the head of femur  and (b) avascular necrosis of head in fracture neck femur    3 The posterior articular surface is divided by a vertical  ridge into a larger lateral and a smaller medial areas.   4 The bone laid on a table rests on the broad lateral  articular area and determines the side of the bone.   The patella has an apex, three borders, superior, lateral  and medial, and two surfaces, anterior and posterior.    The apex directed downwards, is rough and vertically  ridged. It is covered by an expansion from the tendon  of the rectus femoris, and is separated from the skin by  the prepatellar bursa.   The posterior surface is articular in its upper three-  fourths and monarticular in its lower one-fourth.   The articular area is divided by a vertical ridge into  a larger lateral and smaller medial portion. Another   Figs 2.21 a and b: Features of the right patella: (a) Anterior view,  and (b) posterior view    vertical ridge separates a medial strip from the medial  portion. This strip articulates with a reciprocal strip on  the medial side of the intercondylar notch of the femur  during full flexion. The rest of the medial portion and  the lateral portion of the articular surface are divided  by two transverse lines into three pairs of facets.   During different phases of movements of the knee,  different portions of the patella articulate with the  femur. The lower pair of articular facets articulates  during extension; middle pair during beginning of  flexion; upper pair during midflexion; and the medial  strip during full flexion of the knee (Fig. 2.21b).   The superior border or base provides insertion to the rectus  femoris in front and to the vastus intermedius behind.  The lateral border provides insertion to vastus lateralis in  its upper one-third or half. The medial border provides  insertion to the vastus medialis in its upper two-thirds.   The nonarticular area on the posterior surface  provides attachment to the ligamentum patellae below,  and is related to infrapatellar pad of fat above.    The patella ossifies from several centres which appear  during 3 to 6 years of age. Fusion is complete at  puberty.   One or two centres at the superolateral angle of  the patella may form separate pieces of bone. Such a  patella is known as bipartite or tripartite patella. The  condition is bilateral and symmetrical (Fig. 2.22).    • Fracture of the patella should be differentiated  from a bipartite or a tripartite patella (Fig. 2.22).   • The patella has a natural tendency to dislocate  outwards because of the outward angulation  between the long axes of the thigh and leg. This is  prevented by:   a. Bony factor: The lateral edge of the patellar  articular surface of the femur is deeper than the  medial edge.   b. Muscular factor: Insertion of the vastus medialis  on the medial border of patella extends lower  than that of vastus lateralis on the lateral border  (Fig. 2.23). Vastus medialis is first to degenerate  and last to recover in diseases of the knee joint.   • Fascial factor: Medial and lateral patellar  retinacula are extensions of vastus medialis and  vastus lateralis. These strengthen the capsule.  These three are components of the extensor  apparatus of knee joint. During sudden severe  contraction of quadriceps, the tibial tuberosity  may get avulsed. The tibial tuberosity ossifies as  a downward protrusion of upper end.   • Quadriceps femoris muscle is inserted into patella,  from where ligamentum patellae arises which  ends into the tibial tuberosity.   • Bursitis occurs in prepatellar and subcutaneous  infrapatellar bursa (see Fig. 3.6).    The tibia (Latin shin bone) is the medial and larger bone   of the leg. It is homologous with the radius of the upper   1 The upper end is much larger than the lower end.   2 The medial side of the lower end projects downwards  beyond the rest of the bone. The projection is called  the medial malleolus.   3 The anterior border of the shaft is most prominent  and crest-like. It is sinuously curved and terminates  below at the anterior border of the medial malleolus.   The tibia has an upper end, a shaft and a lower end    Fig. 2.24: Anterior view of right tibia and fibula including the  ligaments    Fig. 2.26: Superior view of the upper end of the right tibia   The upper end of the tibia is markedly expanded from  side to side, to form two large condyles which overhang  the posterior surface of the shaft. The upper end includes:   Medial condyle is larger than the lateral condyle. Its  superior surface articulates with the medial condyle of  the femur. The articular surface is oval and its long axis  is anteroposterior. The central part of the surface is  slightly concave and comes into direct contact with the  femoral condyle. The peripheral part is flat and is  separated from the femoral condyle by the medial  meniscus . The lateral margin of the articular surface is  raised to cover the medial intercondylar tubercle.   The posterior surface of the medial condyle has a  groove. The anterior and medial surfaces are marked  by numerous vascular foramina.   The lateral condyle overhangs the shaft more than the  medial condyle. The superior surface of the condyle  articulates with the lateral condyle of the femur. The  articular surface is nearly circular. As in the case of the  medial condyle, the central part is slightly concave and  comes in direct contact with the femur, but the peripheral  part is flat and is separated from the femur by the lateral  meniscus. The articular surface has a raised medial margin  which covers the lateral intercondylar tubercle.   The posteroinferior aspect of the lateral condyle  articulates with the fibula. The fibular facet is flat,  circular, and is directed downwards, backwards and  laterally. Superomedial to the fibular facet, the posterior  surface of the condyle is marked by a groove (Fig. 2.24).   Intercondylar area is the roughened area on the superior  surface, between the articular surfaces of the two  condyles. The area is narrowest in its middle part. This  part is elevated to form the intercondylar eminence  which is flanked by the medial and lateral intercondylar  tubercles (Fig. 2.26).   Tuberosity of the tibia is a prominence located on the  anterior aspect of the upper end of the tibia. It forms  the anterior limits of the intercondylar area. Interiorly  it is continuous with the anterior border of the shaft.  The tuberosity is divided into an upper smooth area  and a lower rough area. The epiphyseal line for the  upper end of the tibia passes through the junction of  these two parts.   The shaft of the tibia is prismoid in shape. It has three  borders, anterior, medial and interosseous; and three  surfaces, lateral, medial and posterior.   The anterior border is sharp and S-shaped being convex  medially in the upper part and convex laterally in the  lower part. It extends from the tibial tuberosity above  to the anterior border of the medial malleolus below. It  is subcutaneous and forms the shin.   The medial border is rounded. It extends from the  medial condyle, above, to the posterior border of the  medial malleolus, below (Fig. 2.24).   The interosseous or lateral border extends from the  lateral condyle a little below and in front of the fibular  facet, to the anterior border of the fibular notch.   The lateral surface lies between the anterior and  interosseous borders. In its upper three-fourths, it is  concave and is directed laterally, and in its lower one-  fourth it is directed forwards.   The medial surface lies between the anterior and medial  borders. It is broad, and most of it is subcutaneous.   The posterior surface lies between the medial and  interosseous borders. It is widest in its upper part. This  part is crossed obliquely by a rough ridge called the  soleal line. The soleal line begins just behind the fibular  facet, runs downwards and medially, and terminates  by joining the medial border at the junction of its upper  and middle thirds (Fig. 2.25).   Above the soleal line, the posterior surface is in the  form of a triangular area. The area below the soleal line  is elongated. It is divided into medial and lateral parts  by a vertical ridge. A nutrient foramen is situated near  the upper end of this ridge. It is directed downwards  and transmits the nutrient artery which is a branch of  the posterior tibial artery (Fig. 2.25).   The lower end of the tibia is slightly expanded. It has  five surfaces. Medially, it is prolonged downwards as  the medial malleolus (Fig. 2.24).   The anterior surface of the lower end has an upper  smooth part, and a lower rough and grooved part.   The medial surface is subcutaneous and is  continuous with the medial surface of the medial  malleolus.   The lateral surface of the lower end presents a  triangular fibular notch to which the lower end of the  fibula is attached. The upper part of the notch is rough.  The lower part is smooth and may be covered with  hyaline cartilage.   The inferior surface of the lower end is articular. It  articulates with the superior trochlear surface of the  talus and thus takes part in forming the ankle joint.  Medially the articular surface extends on to the medial  malleolus.    The medial malleolus is a short but strong process  which projects downwards from the medial surface of  the lower end of the tibia. It forms a subcutaneous  prominence on the medial side of the ankle.   1 The semimembranosus is inserted into the groove on  the posterior surface.   2 The capsular ligament of the knee joint is attached to  the upper border, which also gives attachment to the  deeper fibres of the tibial collateral ligament.   3 The medial patellar retinaculum is attached to the  anterior surface.   1 The iliotibial tract is attached to the flattened impres¬  sion on the anterior surface (Figs 2.24 and 2.27).   2 The capsular ligament of the superior tibiofibular joint  is attached around the margins of the fibular facet.    Fig. 2 .27: Attachments and relations on the anterior aspect of  the right tibia   3 The groove on the posterior surface of the lateral  condyle is occupied by the tendon of the popliteus with  a bursa intervening.   1 The anterior horn of the medial meniscus (Greek small  moon) just in front of the medial articular surface  (Fig. 2.26).   2 The anterior cruciate (Latin cross) ligament on a smooth  area just behind the previous attachment.   3 The anterior horn of the lateral meniscus , to the front of  the intercondylar eminence, and lateral to the  anterior cruciate ligament.   4 The posterior horn of the lateral meniscus , to the  posterior slope of the intercondylar eminence.   5 The posterior horn of the medial meniscus , to the  depression behind the base of the medial inter¬  condylar tubercle.   6 The posterior cruciate ligament , to the posterior-most  smooth area.   The ligamentum patellae is attached to the upper smooth  part of the tibial tuberosity. The lower rough area of the  tuberosity is subcutaneous, but is separated from the  skin by the subcutaneous infrapatellar bursa (Fig. 2.27).   1 The tibialis anterior arises from the upper two-thirds  of the lateral surface.   2 The upper part of the medial surface receives the  insertions of the sartorius, the gracilis and the  semitendinosus , from before backwards (Fig. 2.27).  Still further posteriorly this surface gives attachment  to the tibial collateral ligament along the medial border  (Fig. 2.27).   3 The soleus arises from the soleal line (Fig. 2.28). The  soleal line also gives attachment to the fascia covering  the soleus, the fascia covering the popliteus, and the  transverse fascial septum. The tendinous arch for  origin of the soleus is attached to a tubercle at the  upper end of the soleal line.   4 The popliteus is inserted on the posterior surface, into  the triangular area above the soleal line.   5 The medial area of the posterior surface below the  soleal line gives origin to the flexor digitorum longus  while the lateral area gives origin to the tibialis  posterior.   6 The anterior border of the tibia gives attachment to  the deep fascia of the leg and, in its lower part, to the  superior extensor retinaculum .   7 The rough upper part of the fibular notch gives  attachment to the interosseous tibiofibular ligament.   8 The capsular ligament of the ankle joint is attached to  the lower end along the margins of articular surface.  The deltoid ligament of the ankle joint is attached to  the lower border of the medial malleolus (Fig. 2.24).   Apart from the relations mentioned above, the  following may be noted.   1 The lower part of the anterior surface of the shaft,  and the anterior aspect of the lower end, are crossed  from medial to lateral side by the tibialis anterior,  the extensor hallucis longus, the anterior tibial artery,  the deep peroneal nerve, the extensor digitorum  longus, and the peroneus tertius (Fig. 2.27).   2 The lower most part of the posterior surface of the  shaft and the posterior aspect of the lower end are  related from medial to lateral side to the tibialis  posterior, which lies in a groove, the flexor digitourm  longus, the posterior tibial artery, the tibial nerve,  and the flexor hallucis longus. The groove for the  tendon of the tibialis posterior continues downwards   3 The lower one-third of the medial surface of the shaft  is crossed by the great saphenous vein (see Fig. 8.1).   The nutrient artery to the tibia is the largest nutrient  artery in the body. It is a branch of the posterior tibial  artery which enters the bone on its posterior surface at  the upper end of vertical ridge. It is directed  downwards.    The tibia ossifies from one primary and two  secondary centres. The primary centre appears in the  shaft during the seventh week of intrauterine life. A  secondary centre for the upper end appears just before  birth , and fuses with the shaft at 16-18 years. The  upper epiphysis is prolonged downwards to form  the tibial tuberosity. A secondary centre for the lower  end appears during the first year, forms the medial  malleolus by the seventh year, and fuses with the  shaft by 15-17 years (Fig. 2.29).    * The upper end of tibia is one of the commonest  sites for acute osteomyelitis. The knee joint  remains safe because the capsule is attached near  the articular margins of the tibia, proximal to the  epiphyseal line (Fig. 2.30).   * The tibia is commonly fractured at the junction of  upper two-thirds and lower one-third of the shaft  as the shaft is most slender here. Such fractures may  unite slowly, or may not unite at all as the blood  supply to this part of the bone is poor. This may  also be caused by tearing of the nutrient artery.   * Forward dislocation of the tibia on the talus  produces a characteristic prominence of the  heel. This is the commonest type of injury of the  ankle.    The fibula (Latin clasp/pin) is the lateral and smaller  bone of the leg. It is very thin as compared to the tibia.  It is homologous with the ulna of the upper limb  (Figs 2.24 and 2.25). It forms a mortice of the ankle joint.   1 The upper end, or head, is slightly expanded in all  directions. The lower end or lateral malleolus is  expanded anteroposteriorly and is flattened from  side to side.    Fig. 2.30: The epiphyseal line is distal to the capsular  attachment    2 The medial side of the lower end bears a triangular  articular facet anteriorly, and a deep or malleolar fossa  posteriorly (Fig. 2.31).   The fibula has an upper end, a shaft (Fig. 2.32) and a  lower end.    Fig. 2.31 : Ligaments attached on the medial aspect of lower  end of fibula    Fig. 2.32: Transverse section through shaft of middle two-  fourths of fibula to show its borders and surfaces   It is slightly expanded in all directions. The superior  surface bears a circular articular facet which articulates  with the lateral condyle of the tibia. The apex of the head  or the styloid process projects upwards from its  posterolateral aspect.   The constriction immediately below the head is  known as the neck of the fibula (Figs 2.25 and 2.33).   The shaft shows considerable variation in its form  because it is moulded by the muscles attached to it. It  has three borders—anterior, posterior and interosseous;  and three surfaces—medial, lateral and posterior  (Fig. 2.32).   The anterior border begins just below the anterior aspect  of the head. At its lower end it divides to enclose an  elongated triangular area which is continuous with the  lateral surface of the lateral malleolus (Fig. 2.33).    The posterior border is rounded. Its upper end lies in  line with the styloid process. Below, the border is  continuous with the medial margin of the groove on  the back of the lateral malleolus (Fig. 2.34).   The interosseous or medial border lies just medial to the  anterior border, but on a more posterior plane. It  terminates below at the upper end of a roughened area  above the talar facet of the lateral malleolus. In its upper  two-thirds, the interosseous border lies very close to the  anterior border and may be indistinguishable from it.   The medial surface lies between the anterior and  interosseous borders. In its upper two-thirds, it is very  narrow, measuring 1 mm or less (Figs 2.33 and 2.35).    The lateral surface lies between the anterior and  posterior borders. It is twisted backwards in its lower  part.   The posterior surface is the largest of the three surfaces.  It lies between the interosseous and posterior borders.  In its upper two-thirds, it is divided into two parts by a  vertical ridge called the medial crest (Fig. 2.34).   The tip of the lateral malleolus is 0.5 cm lower than  that of the medial malleolus, and its anterior surface is  1.5 cm posterior to that of the medial malleolus. It has  the following four surfaces.   4 The medial surface bears a triangular articular facet  for the talus anteriorly and the malleolar fossa  posteriorly.   a. The extensor digitorum longus , from the whole of  the upper one-fourth, and from the anterior half  of the middle two-fourths.   b. The extensor hallucis longus , from the posterior half  of its middle two-fourths.   c. The peroneus tertius , from its lower one-fourth  (Fig. 2.35).   2 The part of the posterior surface between the medial  crest and the interosseous border, the grooved part,  gives origin to the tibialis posterior.   3 The part of the posterior surface between the medial  crest and the posterior border gives origin to:   a. Peroneus longus (PL) from its upper one-third, and  posterior half of the middle one-third.   b. The peroneus brevis (PB) from the anterior half of  its middle one-third, and the whole of lower one-  third (Fig. 2.36). The common peroneal nerve  terminates in relation to the neck of fibula.   5 The head of the fibula receives the insertion of the  biceps femoris on the anterolateral slope of the apex.    This insertion is C-shaped. The fibular collateral  ligament of the knee joint is attached within the  C-shaped area (Fig. 2.33).   The origins of the extensor digitorum, the peroneus  longus, and the soleus, described above, extend on  to the corresponding aspects of the head.   The capsular ligament of the superior tibiofibular joint  is attached around the articular facet.   a. Anterior intermuscular septum of the leg ( see Fig. 8.3).   b. Superior extensor retinaculum, to lower part of the  anterior margin of triangular area.   c. Superior peroneal retinaculum, to the lower part of  the posterior margin of triangular area.   The interosseous border gives attachment to the  interosseous membrane. The attachment leaves a gap  at the upper end for passage of the anterior tibial  vessels (Fig. 2.24).   10 The triangular area above the medial surface of the  lateral malleolus gives attachment to:   a. The interosseous tibiofibular ligament, in the  middle. The joint between lower ends of tibia and  fibula is called syndesmoses (Greek binding  together) (Fig. 2.24).   b. Inferior transverse tibiofibular (a part of posterior  tibiofibular) ligament above and posterior  talofibular ligament below to the malleolar fossa  (Fig. 2.31).   c. The capsule of the ankle joint along the edges of  the malleolar articular surface.   d. Slight notch on the lower border gives attachment  to calcaneofibular ligament (Fig. 2.31).   12 The groove on the posterior surface of the malleolus  lodges the tendon of the peroneus brevis, which is  deep, and of the peroneus longus, which is superficial  (Fig. 2.34).    an injury, first there occurs a spiral fracture of  lateral malleolus, then fracture of the medial  malleolus. Finally the posterior margin of the  lower end of tibia shears off. These stages are  termed 1st, 2nd and 3rd degrees of Pott's fracture  (Fig. 2.19).   • The upper and lower ends of the fibula are  subcutaneous and palpable (Fig. 2.37).   • The common peroneal nerve can be rolled against  the neck of fibula. This nerve is commonly injured  here resulting in foot drop (see Figs 6.8 and 7.11).   • Fibula is an ideal spare bone for a bone graft.   • Though fibula does not bear any weight, the lateral  malleolus and the ligaments attached to it are very  important in maintaining stability at the ankle  joint.   The peroneal artery gives off the nutrient artery for the  fibula, which enters the bone on its posterior surface.  The nutrient foramen is directed downwards.    The fibula ossifies from one primary and two  secondary centres. The primary centre for the shaft  appears during the eighth week of intrauterine life.  A secondary centre for the lower end appears during  the first year, and fuses with the shaft by about  sixteen years. A secondary centre for the upper end  appears during the fourth year, and fuses with the  shaft by about eighteen years (Fig. 2.29).   The fibula violates the law of ossification because  the secondary centre which appears first in the lower  end does not fuse last. The reasons for this violation  are:   1. The secondary centre appears first in the lower  end because it is a pressure epiphysis (law states  that pressure epiphysis appear before the  traction epiphysis).   2. The upper epiphysis fuses last because this is  the growing end of the bone. It continues to  grow afterwards along with the upper end of  tibia which is a growing end.    Sometimes a surgeon takes a piece of bone from  the part of the body and uses it to repair a defect  in some other. This procedure is called a bone graft.  For this purpose pieces of bone are easily obtained  from the subcutaneous medial aspect of tibia and  shaft of fibula.   If the foot gets caught in a hole in the ground, there  is forcible abduction and external rotation. In such   The tarsus is made up of seven tarsal bones, arranged  in two rows. In the proximal row, there is the talus  above, and the calcaneus below. In the distal row, there  are four tarsal bones lying side by side. From medial to  lateral side these are the medial cuneiform, the  intermediate cuneiform, the lateral cuneiform and the  cuboid. Another bone, the navicular, is interposed  between the talus and the three cuneiform (Latin wedge)  bones. In other words, it is interposed between the  proximal and distal rows (Fig. 2.38).   The tarsal bones are much larger and stronger than  the carpal bones because they have to support and    in adults. The smaller angle in young children  accounts for the inverted position of their feet.   The medial part of its plantar surface is marked by a  deep groove termed the sulcus tali. The sulcus tali  lies opposite the sulcus calcanei on the calcaneum,  the two together enclosing a space called the sinus  tarsi.   In habitual squatters, a squatting facet is commonly  found on the upper and lateral part of the neck. The  facet articulates with the anterior margin of the lower  end of the tibia during extreme dorsiflexion of the  ankle.   2 The trochlear articular surface of the body is directed  upwards, and the concave articular surface  downwards.   3 The body bears a large triangular, facet laterally, and  a comma-shaped facet medially.   2 Its anterior surface is oval and convex. The long axis  of this surface is directed downwards and medially.  It articulates with the posterior surface of the  navicular bone.   3 The inferior surface is marked by three articular areas  separated by indistinct ridges. The posterior facet is  largest, oval and gently convex; it articulates with the  middle facet on sustentaculum tali of the calcaneum.  The anterolateral facet articulates with the anterior  facet of the calcaneum, and the medial facet with the  spring ligament (Fig. 2.39b) (refer to #).   1 This is the constricted part of the bone between the  head and the body.   2 It is set obliquely on the body, so that interiorly it  extends further backwards on the medial side than  on the lateral side. However, when viewed from  dorsal side, the long axis of the neck is directed  downwards, forwards and medially. The neck-body  angle is 130 to 140 degrees in infants and 150 degrees   The superior surface bears an articular surface, which  articulates with the lower end of the tibia to form the  ankle joint (Fig. 2.39a). This surface is also called the  trochlear surface. It is convex from before backwards and  concave from side to side. It is wider anteriorly than  posteriorly. The medial border of the surface is straight,  but the lateral border is directed forwards and laterally.  The trochlear surface articulates with the inferior  surface of lower end of tibia.   The inferior surface bears an oval, concave articular  surface which articulates with the posterior facet of the  calcaneum to form the subtalar joint (Fig. 12.22a).   The medial surface is articular above and nonarticular  below. The articular surface is comma-shaped and  articulates with the medial malleolus of tibia (Fig. 2.39c).   The lateral surface bears a triangular articular surface  for the lateral malleolus. The surface is concave from  above downwards, and its apex forms the lateral  tubercle of the talus. The posterior part of the lateral  surface is separated from the trochlea by an ill-defined,  small triangular area which articulates with the inferior  transverse tibiofibular ligament (Fig. 2.39d).   The posterior process is small and is marked by an  oblique groove. The groove is bounded by medial and  lateral tubercles. The lateral tubercle is occasionally  separate (5%) and is then called the os trigonum.   The talus is devoid of muscular attachments, but numerous  ligaments are attached to it because it takes part in three  joints, e.g. ankle, talocalcanean and talonavicular:   a. The distal part of the dorsal surface provides  attachment to the capsular ligament of the ankle joint  and to the dorsal talonavicular ligament. The  proximal part of the dorsal surface lies within the  ankle joint.   b. The inferior surface provides attachment to the  interosseous talocalcanean and cervical ligaments.    Figs 2.39a to d: Right talus: (a) Superior view, (b) inferior view, (c) medial view, and (d) lateral view    c. The lateral part of the neck provides attachment  to the anterior talofibular ligament (Figs 2.31  and 2.39d).   2 The lower, nonarticular part of the medial surface of  the body gives attachment to the deep fibres of the  deltoid or anterior tibiotalar ligament (Fig. 2.39c).   3 The groove on the posterior process lodges the  tendon of the flexor hallucis longus (Fig. 2.39a).   The medial tubercle provides attachment to the  superficial fibres of the deltoid ligament (posterior  tibiotalar) above and the medial talocalcanean ligament  below.   Posterior talofibular ligament is attached to upper  part of posterior process while posterior talocalcanean  ligament is attached to its plantar border (Figs 2.39a  and d).    The talus ossifies from one centre which appears  during the 6th month of intrauterine life.    » Forced dorsiflexion may cause fracture of the neck  of the talus.   * If arteries to body of talus go through the neck  only as occurs in some cases, the body would  get avascular necrosis in fracture of its neck  (Fig. 2.40).   The calcaneus (Latin heel) is the largest tarsal bone. It  forms the prominence of the heel. Its long axis is  directed forwards, upwards and laterally. It is roughly  cuboidal and has six surfaces (Fig. 2.41a).   1 The anterior surface is small and bears a  concavoconvex articular facet for the cuboid. The  posterior surface is large and rough.   2 The dorsal or upper surface bears a large convex  articular surface in the middle. The plantar surface  is rough and triangular (Figs 2.41a and b).   3 The lateral surface is flat, and the medial surface  concave from above downwards (Fig. 2.41c).   The anterior surface is the smallest surface of the bone.  It is covered by a concavoconvex, sloping articular  surface for the cuboid (Fig. 2.41c).   The posterior surface is divided into three areas, upper,  middle and lower. The upper area is smooth while the  others are rough.   The dorsal or superior surface can be divided into three  areas. The posterior one-third is rough. The middle one-  third is covered by the posterior facet for articulation  with the facet on inferior surface of body of talus. This    facet is oval, convex and oblique. The anterior one-third  is articular in the anteromedial part, and nonarticular  in its posterolateral part. The articular part is in the form  of an elongated middle facet present on the  sustentaculum tali and anterior facet. These two facets  articulate respectively with posterior facet and  anteromedial facets on inferior aspect of head of talus.   The plantar surface is rough and marked by three  tubercles. The medial and lateral tubercles are situated  posteriorly, whereas the anterior tubercle lies in the  anterior part.   The lateral surface is rough and almost flat. It presents  in its anterior part, a small elevation termed the peroneal  trochlea or tubercle (Fig. 2.41d).   The medial surface is concave from above downwards.  The concavity is accentuated by the presence of a shelf¬  like projection of bone, called the sustentaculum tali ,  which projects medially from its anterosuperior border.  The upper surface of this process assists in the  formation of the talocalcaneonavicular joint. Its lower  surface is grooved; and the medial margin is in the  form of a rough strip convex from before backwards  (Fig. 2.41c).   1 The middle rough area on the posterior surface  receives the insertion of the tendocalcaneus and of  the plantaris. The upper area is covered by a bursa.    Figs 2.41a to d: Right calcaneus: (a) Superior view, (b) inferior view, (c) medial view, and (d) lateral view    The lower area is covered by dense fibrofatty tissue  and supports the body weight while standing. It can  be compared to the attachment of ligamentum  patellae (Fig. 2.42).   2 The lateral part of the nonarticular area on the  anterior part of the dorsal surface provides:   c. Attachment to the stem of the bifurcate ligament. The  medial, narrow part of the nonarticular area forms  the sulcus calcanei, and provides attachment to the  interosseous talocalcanean ligament medially and the  cervical ligament laterally (Fig. 12.17).   ii. The lateral tubercle gives origin to the abductor digiti  minimi, the origin extending to the front of the  tubercle.   iii. The anterior tubercle and the rough area in front  of it provide attachment to the short plantar  ligament. The rough strip between the three  tubercles affords attachment to the long plantar  ligament (Fig. 2.41b).   4 The attachments and relations of the lateral surface  are as follows. The peroneal tubercle lies between  the tendons of the peroneus brevis above and the  peroneus longus below. The trochlea itself gives  attachment to a slip from the inferior peroneal  retinaculum. The calcaneofibular ligament is attached  about 1 cm behind the peroneal trochlea (Fig. 2.41d).   5 The attachments and relations of the medial surface  are as follows. The groove on the lower surface of  the sustentaculum tali is occupied by the tendon of  the flexor hallucis longus. The medial margin of the   c. Some of the superficial fibres of the deltoid ligament  along the whole length.   d. The medial talocalcanean ligament posteriorly. Below  the groove for the flexor hallucis longus, the  medial surface gives origin to the fleshy fibres of  the medial head of the flexor digitorum accessorius  (Fig. 2.41b).    The calcaneus ossifies from one primary and one  secondary centres. The primary centre appears  during the 3rd month of intrauterine life. The  secondary centre appears between 6 and 8 years to  form a scale-like epiphysis on the posterior surface,  which fuses with the rest of the bone by 14-16 years.    • Fracture of the calcaneum results by a fall from a  height. Sustentaculum tali may get fractured in  forced inversion of the foot.   * Calcaneum may develop a 'spur', which is painful  (Fig. 2.43).   The navicular bone is boat-shaped. It is situated on the  medial side of the foot, in front of the head of the talus,  and behind the three cuneiform bones.   1 The anterior surface is convex, is divided into three  facets for the three cuneiform bones.   2 The posterior surface is concave and oval for  articulation with the head of the talus.   3 The dorsal surface is broad and convex from side  to side. It is rough for the attachment of ligaments  (Fig. 2.44).   4 The plantar surface is small and slightly concave  from side to side. It is rough and nonarticular.   5 The medial surface has a blunt and prominent  tuberosity , directed downwards, the tuberosity is  separated from the plantar surface by a groove.   6 The lateral surface is rough and irregular, but  frequently has a facet for the cuboid.   1 Tuberosity of the navicular bone receives the  principal insertion of the tibialis posterior. The  groove below the tuberosity transmits a part of the  tendon of this muscle to other bones.   2 Plantar surface provides attachment to the spring  ligament or plantar calcaneonavicular ligament.    3 Calcaneonavicular part of the bifurcate ligament is  attached to the lateral surface. To the dorsal surface  are attached the talonavicular, cuneonavicular and  cubonavicular ligaments.    It ossifies from one centre which appears during the  third year of life.   1 There are three cuneiform bones, medial, intermediate  and lateral. The medial cuneiform is the largest and  the intermediate cuneiform, the smallest (Fig. 2.44).   2 As their name suggests, these are wedge-shaped  bones. In the medial cuneiform, the edge of the  wedge forms the dorsal surface. In the intermediate  and lateral cuneiforms, the thin edge of wedge forms  the plantar surface.   3 The anterior parts of the medial and lateral  cuneiforms project further forwards than the  intermediate cuneiform. This forms a deep recess for  the base of second metatarsal bone.    Fig. 2.44: Skeleton of the foot as seen from the dorsal aspect   1 Dorsal surface is formed by the rough edge of the  wedge.   2 Plantar surface is formed by the base of the wedge.   3 Distal surface has a large kidney-shaped facet for the  base of the first metatarsal bone, with its hilum  directed laterally.   6 Lateral surface is marked by an inverted  L-shaped facet along the posterior and superior  margins for the intermediate cuneiform bone. The  anterosuperior part of the facet is separated by a  vertical ridge. This part is for the base of second  metatarsal bone. The anteroinferior part of the lateral  surface is roughened.   1 The greater part of the tibialis anterior is inserted  into an impression on the anteroinferior angle of the  medial surface (see Fig. 8.5).   2 The plantar surface receives a slip from the tibialis  posterior ( see Fig. 12.23).   3 A part of the peroneus longus is inserted into  the rough anteroinferior part of the lateral surface  (see Fig. 8.12).   2 The lateral surface is marked by a vertical facet along  its posterior margin. This facet is for the lateral  cuneiform bone. It is indented in the middle.   3 The plantar surface is formed by the edge of the  wedge.   1 The proximal surface is rough in its lower one-third,  and has a triangular facet in its upper two-thirds for  the navicular bone.   2 The lateral surface is marked in its posterosuperior  part by a triangular or oval facet for the cuboid.   3 The plantar surface is formed by the edge of the  wedge.    Each cuneiform bone ossifies from one centre, which  appears during the first year in the lateral cuneiform,  during the second year in the medial cuneiform, and  during the third year in the intermediate cuneiform  bone.   The cuboid is the lateral bone of the distal row of the   1 The proximal surface is concavoconvex for articulation  with the calcaneum.   2 The distal surface is also articular. It is divided by a  vertical ridge into two areas for the fourth and fifth  metatarsal bones.   3 The dorsal surface is rough for the attachment of  ligaments. It is directed upwards and laterally.   4 The plantar surface is crossed anteriorly by an oblique  groove. The groove is bounded posteriorly by a  prominent ridge.   6 The medial surface is extensive, being partly articular  and partly nonarticular. An oval facet in the middle  articulates with the lateral cuneiform bone. Proximal  to this a small facet may present for the navicular  bone.   1 The notch on the lateral surface, and the groove on  the plantar surface, are occupied by the tendon of  the peroneus longus (see Fig. 12.23).   2 The ridge posterior to the groove gives attachment to  the deep fibres of the long plantar ligament ( see Fig. 12.23).   3 The short plantar ligament is attached to the posterior  border of the plantar surface.   5 The nonarticular part of the medial surface provides  attachment to ligaments, including the lateral limb  of the bifurcate ligament.    The cuboid bone ossifies from one centre which  appears just before birth.   1 The metatarsus is made up of 5 metatarsal bones,  which are numbered from medial to lateral side.   2 Each metatarsal is a miniature long bone and has  the following parts.   a. The shaft which is slightly convex dorsally and  concave ventrally in its longitudinal axis. It is  prismoid in form, and tapers from base to the head.   b. The base or proximal end is set obliquely in such a  way that it projects backwards and laterally.   c. The head or distal end is flattened from side to side.   The metatarsals are quite similar to metacarpals. The  differences between the metacarpals and metatarsals  shown in Table 2.1.   3. The dorsal surface of the 3. The dorsal surface of the  shaft has an elongated, flat shaft is uniformly convex  triangular area   4. The base is irregular 4. The base appears to be   1 This is the shortest, thickest and stoutest of all  metatarsal bones and is adapted for transmission of  the body weight (Fig. 2.44).   2 The proximal surface of the base has a kidney-shaped  facet, which is concave outwards.   1 This is the longest metatarsal. It has a wedge-shaped  base (Fig. 2.44).   2 The lateral side of the base has two articular facets, a  larger dorsal, and a smaller plantar each of which is  subdivided into a proximal part for the lateral  cuneiform bone and a distal part for the third  metatarsal.   3 The medial side of the base bears one facet, placed  dorsally, for the medial cuneiform.   1 The lateral side of the base has one facet, placed  dorsally, for the fourth metatarsal bone.    2 The medial side of the base has two facets, dorsal  and plantar for second metatarsal bone.   1 The proximal surface of the base is quadrangular. It  articulates with the cuboid bone.   2 The lateral side of the base has one facet, placed  dorsally, for the fifth metatarsal bone.   3 The medial side of the base has one facet placed  dorsally, which is subdivided into a proximal part  for the lateral cuneiform and a distal part, for third  metatarsal bone.   1 The lateral side of the base has a large tuberosity or  styloid process projecting backwards and laterally.   2 The medial side of the base has one facet for the  fourth metatarsal bone.   3 The plantar surface of the base is grooved by the  tendon of the abductor digiti minimi.   1 A part of the tibialis anterior is inserted on the  medial side of the base of the first metatarsal bone  (see Fig. 12.23).   2 The greater part of the peroneus longus is inserted  on a large impression at the inferior angle of the  lateral surface of the base of the first metatarsal bone  (see Fig. 12.23).   3 The peroneus brevis is inserted on the dorsal surface of  the tuberosity of the fifth metatarsal bone (Fig. 2.44).   4 The peroneus tertius is inserted on the medial part of  the dorsal surface of the base and the medial border  of the shaft of the fifth metatarsal bone (Fig. 2.44).   5 The flexor digiti minimi brevis arises from the plantar  surface of the base of the fifth metatarsal bone.   6 The shafts of metatarsal bones give origin to interossei  (see Figs 10.7 and 10.8).    Each metatarsal bone ossifies from one primary and  one secondary centre. The primary centre appears  in the shaft during the tenth week of foetal life in the  first metatarsal, and during the ninth week of foetal  life in the rest of the metatarsals (Fig. 2.45).   A secondary centre appears for the base of the first  metatarsal during the third year, and for the heads  of the other metatarsals between three and four years.  All secondary centres unite with the shaft by 18th  year. A separate centre for the tuberosity of the fifth  metatarsal bone may be present.   1. The head and shaft are  flattened from side to side   There are 14 phalanges in each foot; 2 for the great toe  and 3 for each of the other toes. As compared to the  phalanges of the hand, these are much smaller in size,  and the shafts particularly of first row are compressed  from side to side. Otherwise their arrangement and  features are similar in two limbs.   a. Lateral four toes, flexor digitorum longus on the  plantar surface, and the extensor expansion on the  dorsal surface (see Fig. 10.5).   b. Great toe, flexor hallucis longus on the plantar  surface, and the extensor hallucis longus on the  dorsal surface (see Fig. 10.5).   a. Second, third and fourth toes: A lumbrical muscle  on the medial side, and an interosseous muscle on  each side (see Figs 10.5,10.7 and 10.8).   b. Fifth toe: A plantar interosseous muscle on the  medial side, and the abductor digiti minimi and  the flexor digiti minimi brevis on the lateral side  (see Figs 10.6a and 10.7).   c. Great toe, abductor hallucis and part of the flexor  hallucis medially , adductor hallucis and the remaining    part of the flexor hallucis brevis laterally (see Figs  10.4a. and 10.6a).   4 The fibrous flexor sheath is attached to the margins of  the proximal and middle phalanges of the lateral four  toes.    Phalanx ossifies by one primary centre for the shaft  which appears in tenth week of foetal life. The single  secondary centre appears in the base. It appears in  the proximal phalanx in second year, middle phalanx  in third year and in distal phalanx in the sixth year.  These fuse with the respective shafts by eighteenth  year. The big toe has two phalanges and their  secondary centres appear in second and third years  to fuse with shaft in 18th year (Fig. 2.45).    • Adventitious bursae develop due to excessive or  abnormal friction, e.g. bursa over tendocalcaneus  due to ill fitting shoes.   • Bunion is an adventitious bursa on the medial side  of the head of 1st metatarsal bone.   • Fracture of tuberosity of 5th metatarsal bone may  occur due to the pull of peroneus brevis muscle.   • Fracture of 2nd, 3rd, 4th or 5th metatarsal bones  is common in soldiers and policemen and is called  "march fracture".   2 There is one sesamoid bone (os peroneum) in the  tendon of peroneus longus. It articulates with the  cuboid.   3 Sesamoid bones may be present in the tendons of  the tibialis anterior, the tibialis posterior, the lateral  head of the gastrocnemius (fabella), the tendon of  adductor longus (rider's bone) and the gluteus  maximus.   4 There are two small sesamoids in the tendon of the  flexor hallucis brevis. They articulate with the head  of the first metatarsal bone.   5 Other tendons crossing the metatarsal, phalangeal  and interphalangeal joints may have sesamoids.    • Iliac crest of lower limb is used for bone marrow  biopsy.   • First metatarsal has two sesamoid bones on the  plantar surface of its head.    A player was kicked hard on the lateral surface of  right knee during a hockey game   • What important structure lies in relation to the  neck of fibula?   • What are the effects of injury to the neck of fibula?   Ans: The head of fibula is palpated from the posterior  aspect of knee joint. The head of fibula is  subcutaneous and lies at the posterolateral aspect of  the knee joint. The neck of fibula lies just beyond the  head. The common peroneal nerve winds around the  neck of fibula where it divides into superficial  peroneal and deep peroneal nerves. In injury to the  neck of fibula, common peroneal nerve is usually  injured, causing paralysis of the dorsiflexors of foot  supplied by deep peroneal nerve and of evertors of  foot supplied by the superficial peroneal nerve,  resulting in 'Toot drop" (see Fig. 8.10)    1. Which part of hip bone is used for taking bone  marrow biopsy in anaemia or leukaemia?   3. Slight notch on lower border of the lateral malleolus  of fibula give attachment to:    Which nerve is commonly injured in relation to  neck of fibula?   5. Medial strip on posterior surface of patella comes  in contact with femur in:   a. Full flexion of knee b. Midflexion  c. Extension d. Slight flexion   7. Which part of ischium forms efficient cushion for  support body weight in sitting position?   8. The greater trochanter of femur does not give  attachment to:   9. Which of the following bone has a groove on  inferior surface for tendon of peroneus longus?   12. Adductor tubercle close to medial condyle of femur  gives insertion to:   a. Adductor longus b. Adductor brevis  c. Adductor magnus d. Pectineus   Front of thigh extends between the hip and knee joints.  The superficial fascia contains one big vein, the great  saphenous vein, besides the cutaneous nerves, vessels,  lymphatics and lymph nodes. The upper third of thigh  medially contains the femoral triangle, middle third  carries the femoral vessels through the adductor canal.  Front of thigh also contains a vast four-headed muscle,  the quadriceps femoris, besides the iliopsoas in the  uppermost region and adductor muscles on its medial  side. Femoral hernia if occurs is seen in the upper  medial region of front of thigh.    Iliac crest is a thick, curved bony margin, forming  laterally the lower margin of the waist. The hands are  often supported on the iliac crests in a relaxed standing  posture. Anterior superior iliac spine is the anterior end  of the iliac crest (Fig. 3.1). Tubercle of the iliac crest is a  low bony prominence situated on the outer lip of the  iliac crest about 5.0 cm behind the anterior superior  iliac spine.   Fold of groin is a shallow curved groove which  separates the front of the thigh from the anterior  abdominal wall. It represents the flexion crease of the  thigh and overlies the inguinal ligament which extends  from the anterior superior iliac spine to the pubic  tubercle. The downward convexity of the ligament is  due to the pull exerted by the fascia lata of the thigh.   Pubic tubercle is a small bony projection felt at the  medial end of the fold of groin. Pubic symphysis is  formed in the median plane between the right and left  pubic bones. Pubic crest is a short bony ridge between  the pubic tubercle and pubic symphysis (Fig. 3.2).   The greater trochanter of femur lies a hand's-breadth  (about 12.5 cm) below the tubercle of iliac crest, formini   a wide (4.5 cm) prominence just in front of the hollow  on the side of the hip. The upper margin of the  trochanter lies about the same level as the pubic crest.   Midinguinal point lies midway between the anterior  superior iliac spine and the pubic symphysis. The  femoral artery and the head of the femur lie beneath  the midinguinal point (Fig. 3.2).   Midpoint of inguinal ligament lies slightly lateral to  midinguinal point. It is the middle point of inguinal  ligament. Femoral nerve lies beneath it.   Patella (knee cap) is the largest sesamoid bone of the  Mac crest, forming body, developed in the tendon of quadriceps femoris.    Fig. 3.2 : The superficial area into which urine may pass when  urethra is injured. The areas within the interrupted lines have a  well-defined membranous layer of superficial fascia    It is easily seen and felt in front of the knee. It can be  moved freely in a fully extended knee.   Tibial tuberosity is a blunt prominence in front of the  upper end of tibia, marking the upper end of the shin.   Ligamentum patellae extends from the apex of patella  to the tibial tuberosity. It represents the tendon (5 x 2.5  cm) of the quadriceps femoris which can be felt best in  a half flexed knee.   The medial and lateral condyles of the femur and of the  tibia form large bony masses at the sides of the knee.  The most prominent points on the sides of the femoral  condyles are called the medial and lateral epicondyles.  Vastus medialis forms a fleshy prominence above the  medial condyle of femur, particularly in an extended  knee.   Adductor tubercle is a bony projection from the  uppermost part of the medial condyle of femur to which  the tendon of adductor magnus is attached. To palpate  the tubercle, flex the knee partly and note the wide,  shallow groove that appears posterior to the mass of  vastus medialis. The tendon of adductor magnus can  be felt in this groove. The tendon can be traced down  to the adductor tubercle.    Reflect the skin laterally, exposing the superficial fatty  and deeper membranous layers of superficial fascia.  Remove the fatty layer.   Identify the great saphenous vein in the medial part  of anterior surface of thigh. Draining into its upper part  are its three superficial tributaries, namely superficial  circumflex iliac, superficial epigastric and superficial  external pudendal. The vertical group of superficial  inguinal lymph nodes lie along the upper part of great  saphenous vein.   Dissect the superficial inguinal ring 1 cm above and  lateral to the pubic tubercle. The spermatic cord and  ilioinguinal nerve leave the abdomen through this ring.   Trace the great saphenous vein backwards till it  pierces the specialised deep fascia known as cribriform  fascia to drain into the femoral vein enclosed in the  femoral sheath.   The skin of thigh in the region around pubic symphysis,  is studded with hair. The presence of few stitches  indicates that embalming for preservation of the body  has been done from this site.   Procedure for embalming: A 6 cm long vertical  incision is given in the upper medial side of thigh. After  reflecting skin and fasciae, femoral sheath is incised to  visualise the femoral artery. About 10 litres of  embalming fluid prepared by mixing appropriate  amounts of formalin, glycerine, water, red lead,  common salt, etc. is put in the embalming machine  connected to a cannula.   A small nick is given in the femoral artery and  cannula introduced so that its tip points towards the  head end and 8.5 litres of fluid is pumped under 20 lb  pressure. Then the direction of cannula is reversed and  rest of fluid is pumped in. Lastly, the skin and fasciae  are sutured.   Make a curved incision from anterior superior iliac spine  to the pubic tubercle.   Give a curved incision around the scrotum/pudendal  cleft towards upper medial side of thigh. Extend it  vertically down below the medial condyle of tibia till the  level of tibial tuberosity.   Now make a horizontal incision below the tibial  tuberosity till the lateral side of leg (Fig. 3.1).    The superficial fascia has two layers, a superficial fatty  layer and a deep membranous layer, which are  continuous with the corresponding layers of the  anterior abdominal wall. The two layers are most  distinct in the uppermost part of the thigh, near the  groin, where the cutaneous nerves, vessels and lymph  nodes lie between the two layers.   The membranous layer is loosely attached to the deep  fascia of the thigh except near the inguinal ligament,  where it is firmly attached along a horizontal line. The  line of firm attachment is called Holden's line. It begins  a little lateral to the pubic tubercle and extends laterally  for about 8 cm (Fig. 3.2).   When the urethra is injured in the perineum, urine  may flow out or extravasate into the interval deep to  the membranous layer of superficial fascia. This urine  can pass up into the anterior abdominal wall from  where it can enter the upper part of the thigh. However,  the firm attachment of the membranous layer of  superficial fascia to the deep fascia along Holden's line  prevents urine from descending into the thigh beyond  the line.   The superficial fascia contains cutaneous nerves,  cutaneous arteries, the great saphenous vein and its  tributaries, and the superficial inguinal lymph nodes.  The nerves and vessels are described below. The  inguinal lymph nodes are described later.   The skin of the front of the thigh is supplied by  following cutaneous nerves derived directly, or  indirectly, from the lumbar plexus (Fig. 3.3).    The ilioinguinal nerve (LI) emerges at the superficial  inguinal ring, and supplies the skin at the root of the  penis or over the mons pubis in the female, the anterior  one-third of the scrotum or labium majus, and the  superomedial part of the thigh (Fig. 3.4).   The femoral branch of genitofemoral nerve (LI, L2)  pierces the femoral sheath and the overlying deep fascia  2 cm below the midinguinal point, and supplies most  of the skin over the femoral triangle (Fig. 3.4).    Fig. 3.4: Superficial veins and nerves seen on the front of the  thigh    The lateral cutaneous nerve of thigh (L2, L3) is a branch  of the lumbar plexus. It emerges behind the lateral end  of the inguinal ligament, divides into anterior and  posterior branches, and supplies the skin on the  anterolateral side of the thigh and on the anterior part  of the gluteal region.   The intermediate cutaneous nerve of thigh (L2, L3) is a  branch of the anterior division of the femoral nerve. It  pierces the deep fascia at the junction of the upper one-  third and middle one-third of the thigh. It divides into  two or more branches and supplies a strip of skin on  the front of the thigh extending from the sartorius to  the knee.   The medial cutaneous nerve of the thigh (L2, L3) is a  branch of the anterior division of the femoral nerve. It  divides into anterior and posterior divisions. The nerve  supplies the skin on the medial side of the lower two-  thirds of the thigh.   The saphenous nerve (L3, L4) is a branch of the  posterior division of the femoral nerve. It pierces the  deep fascia on the medial side of the knee, rims down  in front of the great saphenous vein, and supplies the  skin on the medial side of the leg and foot up to the  ball of the big toe ( see Fig. 8.2).   Before piercing the deep fascia the saphenous nerve  gives off the infrapatellar branch which runs downwards   It is a plexus of fine nerves situated in front of the  patella, the ligamentum patellae and the upper end of  the tibia. It is formed by contributions from:   Three small arteries arising from the femoral artery can  be seen a little below the inguinal ligament (Fig. 3.11).   1 Superficial external pudendal artery pierces the  cribriform fascia, runs medially in front of the  spermatic cord, and supplies the external genitalia.   2 Superficial epigastric artery pierces the cribriform  fascia, runs towards the umbilicus, and supplies the  lower part of anterior abdominal wall.   3 Superficial circumflex iliac artery pierces the fascia lata  lateral to saphenous opening, runs upwards below  the inguinal ligament, and anastomoses at the  anterior superior iliac spine with deep circumflex  iliac, superior gluteal and lateral circumflex femoral  arteries.   This is the largest and longest superficial vein of the  lower limb ( Saphes = easily seen).   It begins on the dorsum of the foot from the medial  end of the dorsal venous arch, and runs upwards in  front of the medial malleolus, along the medial side of  the leg, and behind the knee. In the thigh, it inclines  forwards to reach the saphenous opening where it  pierces the cribriform fascia and opens into the femoral  vein. Before piercing the cribriform fascia, it receives  three named tributaries corresponding to the three  cutaneous arteries, and also many unnamed tributaries  (see Figs 3.4 and 11.1).   The superficial inguinal lymph nodes are variable in their  number and size. Their arrangement is T-shaped, there  being a lower vertical group and an upper horizontal  group. The upper nodes can be subdivided into the  upper lateral and upper medial groups (Fig. 3.5).   2 Upper lateral group drains lymph from infra-  umbilical part of anterior abdominal wall and gluteal  region.   Upper lateral group  drains lower part of  anterior abdominal  wall below umbilicus   Upper medial group  drains skin of  perineum and the  openings in perineum   3 Upper medial group drains lymph from external  genital organs including the terminal ends of the  urethra, anal canal and vagina .   Bursae are lubricating mechanisms which are provided  at sites of friction to smoothen movement. Undue  pressure on them may cause their pathological  enlargement. Bursae present in relation to the patella  are described here (Fig. 3.6).   It lies in front of the lower part of the patella and of the  upper part of the ligamentum patellae.   It lies in front of lower part of the tibial tuberosity and  of the lower part of the ligamentum patellae.   Two deep bursae are also present. These are  suprapatellar bursa and deep infrapatellar bursa.    After the reflection of the superficial fascia, the deep  fascia of thigh is visible. Study its attachments,  modifications and extensions.   Follow the great saphenous vein through the  cribriform fascia and the anterior wall of femoral sheath  into the femoral vein. The femoral vein occupies the  intermediate compartment of the femoral sheath. Medial  compartment of femoral sheath is the femoral canal  occupied by a lymph node while the lateral compartment  is occupied by the femoral artery.   Give a vertical incision in the deep fascia of thigh  from tubercle of iliac crest till the lateral condyle of femur  and remove the deep fascia or fascia lata in lateral part  of thigh. This will expose the tensor fasciae latae muscle  and gluteus maximus muscle getting attached to iliotibial  tract. Identify the four heads of quadriceps femoris  muscle.   Remove the entire deep fascia from upper one-third  of the front of thigh. Identify the sartorius muscle  stretching gently across the thigh from lateral to medial  side and the adductor longus muscle extending from  medial side of thigh towards lateral side into the femur,  being crossed by the sartorius. This triangular  depression in the upper one-third of thigh is the femoral  triangle. The medial border of sartorius forms lateral  boundary and medial border of adductor longus forms  medial boundary. The base of this triangle is formed by  the inguinal ligament. Dissect its boundaries, and  contents, e.g. femoral nerve, artery and vein, and  accompanying structures.   Expose the sartorius muscle till its insertion into the  upper medial surface of shaft of tibia.   The fascia lata is a tough fibrous sheath that envelops  the whole of the thigh like a sleeve. Its attachments,  shown in Fig. 3.7, are as follows:   Superiorly it is attached to the boundary line between  the lower limb and the pelvis. Thus anteriorly it is  attached to the inguinal ligament; laterally to the iliac    crest; posteriorly, through the gluteal fascia to the  sacrum, coccyx and sacrotuberous ligament; and  medially to the pubis, the pubic arch and the ischial  tuberosity.   Inferiorly, on the front and sides of the knee, the fascia  lata is attached to subcutaneous bony prominences and  the capsule of the knee joint. Posteriorly, it forms the  strong popliteal fascia which is continuous below with  the fascia of the back of the leg.   The fascia lata is thickened laterally where it forms a  5 cm wide band called the iliotibial tract (Fig. 3.8).  Superiorly the tract splits into two layers. The  superficial lamina is attached to tubercle of iliac crest,  and deep lamina to the capsule of hip joint. Inferiorly,  the tract is attached to a smooth area on anterior surface  of the lateral condyle of tibia. The importance of the  iliotibial tract is as follows.   a. Two important muscles are inserted into its upper  part, between the superficial and deep laminae.  These are the three-fourths part of the gluteus  maximus; and the tensor fasciae latae.   b. The iliotibial tract stabilizes the knee both in  extension and in partial flexion; and is, therefore,  used constantly during walking and running. In  leaning forwards with slightly flexed knees, the tract  is the main support of the knee against gravity.    The fascia lata is attached to the inguinal ligament.  Extension of the thighs pulls the abdominal wall  downwards and makes it tense. To relax the  abdomen fully for palpation by an examining  physician, the patient is asked to draw the legs up.  This overcomes the pull of the fascia lata on the  abdominal wall.   This is an oval opening in the fascia lata. The centre of  the opening is 4 cm below and 4 cm lateral to the pubic  tubercle. It is about 2.5 cm long and 2 cm broad with its  long axis directed downwards and laterally. The  opening has a sharp crescentic lateral margin or  falciform margin which lies in front of the femoral  sheath. The medial well defined margin of the opening  lies at a deeper level. It is formed by the fascia overlying  the pectineus. The fascia passes behind the femoral  sheath (Fig. 3.4).   The saphenous opening is closed by the cribriform  fascia formed by modification of superficial fascia which  covers the opening.    It is a triangular depression on the front of the upper  one-third of the thigh immediately below the inguinal  ligament.   The femoral triangle is bounded laterally by the medial  border of sartorius; and medially by the medial border  of the adductor longus (Figs 3.10 to 3.12). Its base is  formed by the inguinal ligament . The apex , which is  directed downwards, is formed by the point where the  medial and lateral boundaries cross.   Three intermuscular septa divide the thigh into three  compartments (Fig. 3.9).   The lateral intermuscular septum is the thickest of these  septa. It extends from the iliotibial tract to the lateral  lip of the linea aspera. It separates the anterior  compartment of the thigh from the posterior compar¬  tment.   The medial intermuscular septum is attached to the  medial lip of the linea aspera, and separates the anterior  compartment of the thigh from the medial compartment.   The posterior intermuscular septum is poorly defined.  It separates the medial compartment of the thigh from  the posterior compartment.   b. Superficial fascia containing the superficial  inguinal lymph nodes, the femoral branch of the  genitofemoral nerve, branches of the ilioinguinal  nerve, superficial branches of the femoral artery  with accompanying veins, and the upper part of  the great saphenous vein.   c. Deep fascia, with the saphenous opening and the  cribriform fascia (Fig. 3.10b).   The floor of the triangle is formed medially by the  adductor longus and pectineus , and laterally by the psoas  major and iliacus (Figs 3.10 a and b).    The contents of the femoral triangle (Fig. 3.11) are as  follows:   1 Femoral artery and its branches: The femoral artery  traverses the triangle from its base at the midinguinal  point to the apex. In the triangle, it gives off six  branches, three superficial and three deep.   2 Femoral vein and its tributaries: The femoral vein  accompanies the femoral artery. The vein is medial  to the artery at base of triangle, but posteromedial  to artery at the apex.   The femoral vein receives the great saphenous  vein, circumflex veins and veins corresponding to  the branches of femoral artery.    Figs 3.10a and b: Floor of the femoral triangle: (a) Surface view, and (b) sectional view   Lateral femoral circumflex artery  Profunda femoris artery  Rectus femoris  Lateral cutaneous nerve of thigh    3 The femoral sheath encloses the upper 4 cm of the  femoral vessels (Fig. 3.12).   a. The femoral nerve lies lateral to the femoral artery,  outside the femoral sheath , in the groove between  the iliacus and the psoas major muscles. It is  described later.   b. The nerve to the pectineus arises from the femoral  nerve just above the inguinal ligament. It passes  behind femoral sheath to reach the anterior surface  of pectineus.    c. The femoral branch of the genitofemoral nerve  occupies the lateral compartment of the femoral  sheath along with the femoral artery. It supplies  most of the skin over the femoral triangle.   d. The lateral cutaneous nerve of the thigh crosses the  lateral angle of the triangle. Runs on the lateral  side of thigh and ends by dividing into anterior  and posterior branches. These supply anterolateral  aspect of front of thigh and lateral aspect of gluteal  region respectively.   The deep inguinal lymph nodes lie deep to the deep  fascia. These lie medial to upper part of femoral vein    Fig. 3 .12: Femoral sheath enclosing the upper parts of the  femoral vessels   Fig. 3.13: Formation of the femoral sheath by extension of the  fascia transversalis and the fascia iliaca into the thigh    and receive lymph from superficial inguinal lymph  nodes, from glans penis or clitoris and deep  lymphatics of lower limb.   This is a funnel-shaped sleeve of fascia enclosing the  upper 3 to 4 cm of the femoral vessels. The sheath is  formed by downward extension of two layers of the  fascia of the abdomen. The anterior wall of the sheath  is formed by the fascia transversalis which lies in the  anterior abdominal wall deep to the transversus  abdominis; and the posterior wall is formed by the  fascia iliaca, which covers the iliacus muscle (Fig. 3.13).  Inferiorly, the sheath merges with connective tissue  around the femoral vessels.   The femoral sheath is asymmetrical. Its lateral wall  is vertical, and the medial wall is oblique being directed  downward and laterally (Fig. 3.14).   The sheath is divided into the following three  compartments by septa (Fig. 3.14).   a. The lateral or arterial compartment contains the  femoral artery and the femoral branch of the  genitofemoral nerve.   c. The medial or lymphatic compartment is the smallest  of all, and is known as the femoral canal which is  described below.    The base or upper end of femoral canal is called  femoral ring. The boundaries of ring are important.   It is bounded anteriorly by the inguinal ligament,  posteriorly by pectineus and its covering fascia, medially  by the concave margin of lacunar ligament, and laterally  by the septum separating it from femoral vein.   The inferior epigastric vessels are closely related to  junction of the anterior and lateral walls of ring.  The femoral ring is closed by a condensation of  extraperitoneal connective tissue called the femoral  septum.   This is the medial compartment of the femoral sheath.  It is conical in shape, being wide above or at base and  narrow below. It is about 1.5 cm long, and about 1.5 cm  wide at the base (Figs 3.14, 3.15 and 3.18).    The parietal peritoneum covering septum from  above shows a depression called femoral fossa.   The femoral canal contains a lymph node of Cloquet  or of Rosenmuller , lymphatics, and a small amount of  areolar tissue. The lymph node drains the glans penis  in males and the clitoris in females.    * Femoral hernia: The femoral canal is an area of  potential weakness in the abdominal wall through  which abdominal contents may bulge out forming  a femoral hernia. A femoral hernia is more  common in females because the femoral canal is  wider in them than in males. This is associated  with the wider pelvis, and the smaller size of the  femoral vessels, in the female (Fig. 3.16).   Hernia comprises a neck and a sac. Coverings  are the various layers on the sac. Mostly the  content of hernial sac is a loop of bowel (Fig. 3.17).   * The course of an enlarging hernial sac is typical.  First it passes downwards through the femoral  canal, then forwards through the saphenous  opening, and finally upwards along with the  superficial epigastric and superficial circumflex  iliac vessels. For reduction of such a hernia the  reverse course has to be followed (Fig. 3.18).   • In cases of strangulation of a femoral hernia, the  surgeon has to enlarge the femoral ring. This is  possible only by cutting the lacunar ligament;  which forms the medial boundary of the ring.  Normally this can be done without danger.  Occasionally, however, an abnormal obturator  artery may lie along the edge of the lacunar  ligament; and cutting it may cause alarming  haemorrhage (Fig. 3.19).   • Abnormal obturator artery: The normal obturator  artery is a branch of the internal iliac. It gives a  pubic branch which anastomoses with the pubic  branch of the inferior epigastric artery.  Occasionally, this anastomosis is large and the  obturator artery then appears to be a branch of  the inferior epigastric. Usually, the abnormal  artery passes lateral to the femoral canal in contact  with the femoral vein and is safe in an operation    to enlarge the femoral ring. Sometimes, however,  the abnormal obturator artery may lie along the  medial margin of the femoral ring, i.e. along the  free margin of the lacunar ligament. Such an artery  is likely to be cut if an attempt is made to enlarge  the femoral ring cutting lacunar ligament (Fig. 3.19).   • Lateral cutaneous nerve of thigh may get  entangled in the inguinal ligament. This leads to  pain on lateral side of thigh. It is called "meralgia  parasthetica /f (Fig. 3.20B).   • The femoral artery is exposed in the adductor  canal for various surgical procedures.   This is the chief artery of the lower limb. Develop-  mentally it is not derived from the axis artery. The  original axis artery in the uppermost part of the limb is  represented by the inferior gluteal artery.    It is the continuation of external iliac artery. It begins  behind the inguinal ligament at the midinguinal point.    Adductor longus  Femoral canal and the course of a femoral hernia    Internal oblique  Transversus abdominis  Fascia transversalis  Peritoneum  Fascia iliaca  Femoral fossa  Pectineal fascia    Fig. 3.19: Pubic region seen from behind to show the course  of an abnormal obturator artery: a = femoral canal; b = femoral  vein; c = junction of external iliac and femoral arteries; x =  usual safe course of abnormal obturator artery; y = occasional  dangerous position of artery   Fig. 3.20: (A) Sensory loss due to injury to femoral nerve,  and (B) meralgia parasthetica   It passes downwards and medially, first in the femoral  triangle, and then in the adductor canal. At the lower  end of the adductor canal, i.e. at the junction of the  middle and lower thirds of the thigh it passes through  an opening in the adductor magnus to become  continuous with the popliteal artery (Fig. 3.21).   Anterior: Skin, superficial fascia, deep fascia and the  anterior wall of the femoral sheath.   Posterior: Psoas major, the pectineus, and the adductor  longus. The posterior wall of the femoral sheath  intervenes between these structures and the artery  (Kg. 3.22).   Medial: The femoral vein. Just below the inguinal  ligament the vein is medial to the artery. However, the  vein gradually crosses to the lateral side posterior to the  artery. It is directly behind the artery at the apex of the  femoral triangle, and lateral to the lower end of the artery.   Lateral: The femoral nerve is lateral to the upper part of  the artery. Lower down the artery is related to the  branches of the nerve.   The femoral artery gives off three superficial and three  deep branches in the femoral triangle.   a. Superficial external pudendal supplies the skin  of external genital organs (Fig. 3.11).   b. Superficial epigastric for skin and fasciae of lower  part of anterior abdominal wall.    Popliteal artery  Fig. 3.21: Course and extent of the femoral artery   This is the largest branch of the femoral artery (Fig. 3.22).  It is the chief artery of supply to all the three  compartments of the thigh.    It arises from the lateral side of the femoral artery  about 4 cm below the inguinal ligament. The origin lies  in front of the iliacus.   As the artery descends, it passes posterior to the  femoral vessels. It leaves the femoral triangle by passing  deep to the adductor longus. Continuing downwards,  it passes first between the adductor longus and the  adductor brevis, and then between the adductor longus  and the adductor magnus. Its terminal part pierces the  adductor magnus to anastomose with upper muscular  branches of the popliteal artery.   The profunda femoris artery gives off the medial and  lateral circumflex femoral arteries, and three  perforating arteries (see Fig. 7.12). It itself ends as the  fourth perforating artery.   The medial circumflex femoral artery leaves the femoral  triangle by passing posteriorly, between the pectineus  and the psoas major muscles. It gives an acetabular,  branch and divides into an ascending and transverse  branches. It supplies adductor muscles and head of  femur.   The lateral circumflex femoral artery runs laterally  between the anterior and posterior divisions of the  femoral nerve, passes behind the sartorius and the  rectus femoris, and divides into ascending, transverse  and descending branches.   The ascending branch runs deep to the tensor fasciae  latae, gives branches to the hip joint and the greater  trochanter, and anastomoses with the superior gluteal  artery.   The transverse branch pierces the vastus lateralis and  takes part in the cruciate anastomosis on the back of  the thigh just below the greater trochanter.   Fig. 3.22: Anterior and posterior relations of the femoral artery in the femoral triangle    Inguinal ligament  Femoral sheath  Psoas tendon  Hip joint  Iliac bursa  Nerve to pectineus    The descending branch runs down along the anterior  border of the vastus lateralis, accompanied by the nerve  to that muscle.   Four perforating arteries are described in Chapter 7.  These supply muscles attached to linea aspera.   This branch of the femoral artery passes deep to the  spermatic cord, or the round ligament of the uterus, and  supplies the scrotum or the labium majus.   Numerous muscular branches arise from the femoral and  profunda femoris artery, or its branches, to supply the  muscles of the thigh.    * The femoral artery can be compressed at the  midinguinal point against the head of the femur  or against the superior ramus of the pubis to  control bleeding from the distal part of the limb  in the thigh or leg.   * Pulsations of the femoral artery can be felt at the  midinguinal point, against the head of the femur  and the tendon of the psoas major. A bilateral  absence or feebleness of the femoral pulse may  result from coarctation or narrowing of the aorta,  or thrombosis, i.e. clotting of blood within the  aorta (Fig. 3.23).   * Stab wounds at the apex of the femoral triangle  may cut all the large vessels of the lower limb  because the femoral artery and vein, and the  profunda femoris artery and vein are arranged in  one line from before backwards at this site  (Fig. 3.24). Injury to femoral vessels results in fatal  haemorrhage.   * Since the femoral artery is quite superficial in the  femoral triangle, it can be easily exposed for  ligation, i.e. tying, or for passing a cannula or a  thick needle. Catheters are passed upwards till the  heart for certain minor operation (Fig. 3.25).   * The femoral vein is commonly used for intravenous  infusions in infants and in patients with peripheral  circulatory failure.    It begins as an upward continuation of the popliteal  vein at the lower end of the adductor canal, and ends  by becoming continuous with the external iliac vein  behind the inguinal ligament, medial to the femoral  artery (Figs 3.11 and 3.14).   b. Veins accompanying three deep branches of  femoral artery in femoral triangle, i.e. profunda,  deep external pudendal, and muscular.   d. The descending genicular and muscular veins in  the adductor canal.    The femoral nerve is the chief nerve of the anterior  compartment of the thigh.   It is the largest branch of the lumbar plexus. It is formed  by the dorsal divisions of the anterior primary rami of  spinal nerves L2, L3 and L4 (Fig. 3.3).   It enters the femoral triangle by passing behind the  inguinal ligament just lateral to the femoral artery.   In the thigh, it lies in the groove between the iliacus  and the psoas major, outside the femoral sheath, and  lateral to the femoral artery. The nerve is not included  in the femoral sheath as its formation is behind the fascia  iliaca which is forming posterior wall of the sheath.   After a short course of about 2.5 cm below the  inguinal ligament, the nerve divides into anterior and  posterior divisions which are separated by the lateral  circumflex femoral artery (Figs 3.11 and 3.26).   2 The posterior division supplies the rectus femoris,  the three vasti and the articularis genu. The  articularis genu is supplied by a branch from the  nerve to vastus intermedius.   1 The anterior division gives two cutaneous branches,  the intermediate and the medial cutaneous nerves  of the thigh.   2 The posterior division gives only one cutaneous  branch, the saphenous nerve.   Branches and distribution of femoral nerve are  shown in Fig. 3.26.   1 The hip joint is supplied by the nerve to the rectus  femoris.   2 The knee joint is supplied by the nerves to the three  vasti. The nerve to the vastus medialis contains  numerous proprioceptive fibres from the knee joint,  accounting for the thickness of the nerve. This is in  accordance with Hilton's law: Nerve supply to a  muscle which lies across a joint, not only supplies  the muscle, but also supplies the joint beneath and  the skin overlying the muscle.    *The nerve to the pectineus arises from the medial side of the  femoral nerve just above the inguinal ligament. It passes  obliquely downwards and medially, behind the femoral sheath,  to reach the anterior surface of the muscle.    Injury to the femoral nerve by wounds in the groin,  though rare, causes paralysis of the quadriceps  femoris and a sensory deficit on the anterior and  medial sides of the thigh and medial side of leg  (Fig. 3.20A).    The muscles of the anterior compartment of the thigh  are the sartorius, the quadriceps femoris, and the  articularis genu (Figs 3.27 and 3.28). In addition to these,  some muscles belonging to other regions are also  encountered on the front of the thigh. The iliacus and  psoas major muscles, which form part of the floor of  the femoral triangle, have their origin within the  abdomen. The pectineus and adductor longus, also seen  in relation to the femoral triangle, are muscles of the    Ligamentum patellae  Fig. 3.27: Muscles seen on the front of the thigh    medial compartment of the thigh. They are described  in Chapter 4. In the upper lateral corner of the front of  the thigh, we see the tensor fasciae latae. This is a muscle  of the gluteal region and is described in Chapter 5.   The sartorius (sartor = tailor) is long, narrow and  ribbon—like. It runs downwards and medially across  the front of the thigh. It is the longest muscle in the    body (Fig. 3.29). Its attachments are given in Table 3.1.  Its nerve supply and actions are given in Table 3.2.   The quadriceps femoris is so called because it consists  of four parts. These are the rectus femoris, the vastus  lateralis, the vastus medialis, and the vastus  intermedius. The rectus femoris is fusiform. It runs  more or less vertically on the front of the thigh  superficial to the vasti. The three vasti are wrapped  around the shaft of the femur in the positions indicated  by their names. The attachments of the components of  the quadriceps femoris are given in Table 3.1. Their  nerve supply and actions are given in Table 3.2.   The articularis genu consists of a few muscular slips  that arise from the anterior surface of the shaft of the  femur, a few centimetres above the patellar articular  margin. They are inserted into the upper part of the  synovial membrane of the knee joint. They pull the  synovial membrane upwards during extension of the  knee, thus preventing damage to it.   These muscles form the lateral part of the floor of the  femoral triangle. They are classified as muscles of the  iliac region, and also among the muscles of the posterior  abdominal wall. Since the greater parts of their fleshy  bellies lie in the posterior abdominal wall, they will be  described in detail in the section on the abdomen.  However, on account of their principal action on the  hip joint, the following points may be noted.   1 Both have a common insertion on the lesser  trochanter of the femur and are the chief and  powerful flexors of the hip joint.   2 Because of their common insertion and action, the  two muscles are often referred to by a common name,  the iliopsoas.   Medial cutaneous nerve of thigh  Femoral artery  Femoral vein  Adductor longus  Gracilis  Profunda vessels  Adductor brevis  Adductor magnus  Semimembranosus  Semitendinosus  Sciatic nerve   Lateral intermuscular septum  Short head of biceps femoris (muscle)  Iliotibial tract    Fig. 3.28: Transverse section through the upper third of the thigh    Table 3.1: Muscles of the anterior or extensor compartment of thigh   A. Rectus femoris (Fig. 3.27)  fusiform, superficial fibres  bipennate, deep fibres  straight   B. Vastus lateralis (Fig. 3.27)  forms large part of  quadriceps femoris    • Straight head: from the upper half of the  anterior inferior iliac spine   • Reflected head: from the groove above the  margin of the acetabulum and the capsule  of the hip joint   Upper part of the medial surface of the  shaft of the tibia in front of the insertions  of the gracilis and the semitendinosus    Lateral part of the base of patella  Upper one-third of the lateral border  of patella   Expansion to the capsule of knee  joint, tibia and iliotibial tract   Medial one-third of the base and  upper two-thirds of the medial  border of the patella    *The patella is a sesamoid bone in the tendon of the quadriceps femoris. The ligamentum patellae is the actual tendon of the quadriceps femoris,  which is inserted into the upper part of tibial tuberosity   These actions are involved in assuming the position in which  a tailor work, i.e. palthi posture used during prayer sessions  also.   Extends knee joint, prevents lateral displacement of patella.  Rotates femur medially during locking stage of extension of  knee joint. Action is extremely important for stability of patella.   It pulls the synovial membrane upwards during extension of  the knee, thus preventing damage to it   3 Both are supplied by spinal segments L2 and L3. The  psoas is supplied by the branches from the nerve  roots, whereas the iliacus is supplied by the femoral  nerve.    • Testing for Quadriceps Femoris: A person lies supine  with one bare lower limb and hip and knee joints  partially flexed. The right hand of physician  presses the person's right leg downwards. He is  requested to straighten the knee against resistance  of the physician's right hand, while his left hand  feels the contracting quadriceps muscle above the  knee (Fig. 3.29).   • Patellar tendon reflex or knee jerk (L3, L4). The knee  joint gets extended on tapping the ligamentum  patellae (Fig. 3.30).   • Psoas abscess formed due to tubercular infection  of lumbar vertebrae can track down between  psoas major muscles and its fascia to reach behind  the inguinal ligament into the femoral triangle. It  may be mistaken for enlarged lymph nodes  (Fig. 3.31).   • Intramuscular injection can be given in  anterolateral region of thigh in the vastus lateralis  muscle (Fig. 3.32).   Upper one-third of sartorius forms the lateral boundary  of the femoral triangle.   On lifting the middle one-third of sartorius, a part of  deep fascia stretching between vastus medialis and  adductor muscles is exposed. On longitudinal division  of this strong fascia, the adductor canal subsartorial  canal/Hunter’s canal is visualised (Fig. 3.33).   Dissect its contents, e.g. femoral vessels, saphenous  nerve and nerve to vastus medialis, and distal parts of  both divisions of obturator nerve.    Fig. 3.34: Transverse section through the middle of the right  adductor canal, seen from above. Note the boundaries and  contents of the canal   This is also called the subsartorial canal or Hunter's  canal. John Hunter (1729-93) was an anatomist and  surgeon at London. Hunter's operation for the  treatment of popliteal aneurysm by ligating the femoral  artery in the adductor canal is a landmark in the history  of vascular surgery.   The adductor canal is an intermuscular space  situated on the medial side of the middle one-third of  the thigh (Figs 3.33 and 3.34).   The canal extends from the apex of the femoral triangle,  above, to the tendinous opening in the adductor  magnus, below.   • The posteromedial wall or floor is formed by the  adductor longus, above, and the adductor magnus,  below.   • The medial wall or roof is formed by a strong  fibrous membrane joining the anterolateral and  posteromedial walls. The roof is overlapped by the  sartorius.    The subsartorial plexus of nerves lies on the fibrous  roof of the canal under cover of the sartorius. The plexus  is formed by branches from the medial cutaneous nerve  of the thigh, the saphenous nerve, and the anterior  division of the obturator nerve. It supplies the overlying  fascia lata and the neighbouring skin.   1 The femoral artery enters the canal at the apex of the  femoral triangle. Within the canal it gives off  muscular branches and a descending genicular  branch. The descending genicular artery is the last  branch of the femoral artery arising just above the  hiatus magnus. It divides into a superficial  saphenous branch that accompanies the saphenous  nerve, and a deep muscular branch that enters the  vastus medialis and reaches the knee. Femoral artery  leaves the adductor canal through the opening in  adductor magnus muscle to continue as popliteal  artery in the popliteal fossa.   2 Femoral vein begins as the upward continuation of  popliteal vein from the popliteal fossa. The femoral vein  lies posterior to the femoral artery in the upper part,  and lateral to the artery in the lower part of the canal.   3 The saphenous nerve crosses the femoral artery  anteriorly from lateral to medial side. It leaves the  canal with the saphenous artery by piercing the  fibrous roof.   4 The nerve to the vastus medialis lies lateral to the  femoral artery, and enters the vastus medialis in the  upper part of the canal.    5 Branches of two divisions of obturator nerve: The anterior  division emerges at the lower border of the adductor  longus, gives branches to the subsartorial plexus, and  ends by supplying the femoral artery. The posterior  division of the obturator nerve rims on the anterior  surface of the adductor magnus, accompanies the  femoral and popliteal arteries, and ends by supplying  the knee joint (Fig. 3.34).   • Femoral hernia is common in female, while  inguinal hernia is common in male   • Embalming for preservation of the dead body is  also done through femoral artery   • Insertion of vastus medialis extends to lower level  on patella than that of vastus lateralis to stabilise  the patella.    A 50-year-old woman complained of a swelling in  upper medial side of her right thigh, when she coughs.   • Where is the swelling and why does it appear  when she coughs?   • What is the position of the swelling in relation to  pubic tubercle?   Ans: The swelling is the femoral hernia which  appears at saphenous opening when she coughs due  to raised intra-abdominal pressure. The swelling is  inferolateral to the pubic tubercle. The femoral hernia  is more common in females due to larger pelvis,  larger femoral canal and smaller femoral vessels.   2. Which of these pair of muscle are inserted into  upper part of iliotibial tract?   4. Which one of the following make lateral boundary  of femoral triangle?    9. Which muscles have common insertion on lesser  trochanter of femur?   10. A femoral hernia is more common in female due  to:    11. Which region of thigh is preferred to give  intramuscular injection in children?   12. Which vein is commonly used for intravenous  infusions in children?   The adductor or medial compartment of thigh is very  well developed and is derived, as indicated by its nerve  supply from both the flexors and extensors between  which it lies. Its counterpart in the arm is represented only  by coracobrachialis muscle, as the arm can be adducted  by pectoralis major and latissimus dorsi muscles.   The triangular adductor longus was seen to form the  medial boundary of femoral triangle ( see Fig. 3.11). Cut  this muscle 3 cm below its origin and reflect the distal  part laterally. On its deep surface, identify the anterior  division of obturator nerve which supplies both adductor  longus and gracilis muscles.   Lateral to adductor longus on the same plane is the  pectineus muscle. Cut it close to its origin and reflect  laterally, tracing the branch of anterior division of  obturator nerve to this muscle. Obturator nerve is  accompanied by the branches of obturator artery and  medial circumflex femoral arteries.   Deeper to adductor longus and pectineus is the  adductor brevis. Look for its nerve supply either from  anterior/posterior division.   Divide adductor brevis close to its origin. Deepest  plane of muscles comprises adductor magnus (Fig. 4.2)  and obturator externus, both supplied by posterior  division of obturator nerve.   Lying vertically along the medial side of thigh is the  graceful gracilis. Study these muscles and the course of  obturator nerve.   Lastly, remove the obturator externus from its origin  to expose the obturator artery and its branches.   The adductor or medial compartment of the thigh is  bounded anteriorly by the medial intermuscular  septum which separates it from the extensor (anterior)  compartment; and posteriorly by an ill-defined  posterior intermuscular septum which separates it from  the flexor (posterior) compartment (see Fig. 3.9).   The structures to be studied in this region are  muscles, nerves and arteries. These are as follows.   The obturator externus lies deep in this region. It is  functionally related to the gluteal region.    The attachments of the muscles are given in Table 4.1.  Their nerve supply and actions are given in Table 4.2.   This is a triangular muscle, forming  the medial part of the floor of the  femoral triangle. It lies in the plane  of the pectineus   It arises by a narrow, flat tendon from the  front of the body of the pubis in the angle  between the pubic crest and the pubic  symphysis. Sometimes sesamoid  bone is seen near its origin (rider’s bone)   The linea aspera in middle one-third of  the shaft of the femur between the  vastus medialis and the adductor brevis  and magnus (Fig. 4.2a)   b. Outer surface of inferior ramus of the  pubis between the gracilis and  obturator externus   c. Outer surface of ramus of the ischium  between gracilis and the adductor magnus   Line extending from the lesser trochanter  to upper part of linea aspera, behind  the upper part of adductor longus  (Fig. 4.2a)   This is the largest muscle of this  compartment. Because of its  double nerve supply, it is called  a hybrid muscle   a. Medial margin of the lower half of the  body of the pubis   Upper part of the medial surface of tibia  behind the sartorius and in front of the  semitendinosus (Fig. 4.2b)   Pectineus (see Figs 3.11 and 4.1)  This is flat, quadrilateral muscle   It forms a part of the floor of the  femoral triangle   b. Upper half of the pectineal surface of  superior ramus of the pubis   Adductor longus, adductor brevis help in  adduction and flexion of thigh   Double nerve supply: Adductor part by posterior  division of obturator nerve   Adductor part causes adduction of thigh and  hamstring part helps in extension of hip and  flexion of knee   Flexor and medial rotator of thigh. It is a weak  adductor of thigh. It is used for transplantation of  any damaged muscles   Double nerve supply: Anterior fibres by femoral nerve  Posterior fibres by anterior division of obturator nerve    The obturator externus is described in Chapter 5  (see also Tables 5.1 and 5.2).   The relations of the adductor longus are important.  They are as follows.    Fig. 4.1: Origin of muscles of medial compartment of the thigh    Figs 4.2a and b: Insertion of muscles: (a) Posterior aspect of  femur, and (b) upper part of medial surface of tibia    Fig. 4.3 : Transverse section through the femoral triangle  showing the relations of the adductor longus   The obturator nerve is the chief nerve of the medial  compartment of the thigh.   It is a branch of the lumbar plexus. It is formed by the  ventral divisions of the anterior primary rami of spinal  nerves L2, L3, L4. The upper part of the nerve lies in  the pelvis. It enters the thigh by passing through the  obturator canal (Fig. 4.4) (refer to #).    Fig. 4.4 : The course and distribution of the obturator nerve   1 Within the obturator canal the nerve divides into  anterior and posterior divisions.   2 The anterior division passes downwards in front of  the obturator externus being separated from the  posterior division by a few fibres of this muscle. It  then descends behind the pectineus and the adductor  longus, and in front of the adductor brevis. The  anterior division supplies the following muscles.   The anterior division also gives a branch to the  hip joint. Below the lower border of the adductor  longus, it supplies a twig to the subsartorial plexus,  and ends by supplying the femoral artery in the  adductor canal.   3 The posterior division enters the thigh by piercing the  upper border of the obturator externus muscle. It  descends behind the adductor brevis and in front of  the adductor magnus. It gives branches to the  following muscles.   In the adductor canal, it is reduced to a thin  genicular branch which enters the popliteal fossa,  pierces the oblique popliteal ligament and ends by  supplying the capsule and the cruciate ligaments of  the knee joint. Some of its fibres end by innervating  the popliteal artery.    • Testing the adductors: The patient lies supine with  right lower limb abducted. The right hand of  physician holds the leg in abducted position.  Patient is requested to bring the thigh medially  against the resistance of the physician's right hand,  while his left hand feels the contracting adductor  muscles (Fig. 4.5).   • Spasm of the adductors of thigh in certain  intractable cases of spastic paraplegia may be  relieved by surgical division of the obturator nerve.   • A disease of the hip joint may cause referred pain  in the knee and on the medial side of the thigh  because of their common nerve supply by the  obturator nerve.   • Obturator nerve may be involved with femoral  nerve in retroperitoneal tumors. A nerve  entrapment syndrome leading to chronic pain on  the medial side of thigh may occur in athletes with  big adductor muscles.   This nerve is present in about 30% of subjects. It is a  branch of the lumbar plexus, and is formed by the   Dorsal divisions of ventral primary rami of  lumbar 2, 3, 4 segments of spinal cord   Ventral divisions of ventral primary rami of  lumbar 2, 3, 4 segments of spinal cord   Exits from abdomen by lying on the lateral wall  of true pelvis and then through the obturator  foramen   Supplies muscles of front of thigh of, i.e.  quadriceps femoris and sartorius. Gives big  cutaneous branches.   ventral divisions of the anterior primary rami of spinal  nerves L3 and L4. It descends along the medial border  of the psoas major, crosses the superior ramus of the  pubis behind the pectineus, and terminates by dividing  into three branches. One branch supplies the deep  surface of the pectineus, another supplies the hip joint,  and the third communicates with the anterior division  of the obturator nerve. Sometimes the nerve is very  small, and ends by supplying the pectineus only  (Fig. 4.6).    and first perforating branch of profunda femoris to  form "cruciate anastomoses" (Fig. 4.7).   5 Before giving off the terminal branches, the artery  gives off many muscular branches, and an acetabular  branch which passes through the acetabular notch to  supply fat in the acetabular fossa. It also sends a twig  to the head of the femur along the round ligament  (foveolar artery) (Fig. 4.7).   1 The obturator artery is a branch of the internal iliac,  and accompanies (lies below) the obturator nerve in  the pelvis.   2 At the upper margin of the obturator foramen, the  obturator artery divides into anterior or medial and  posterior or lateral branches which form a circle over  the obturator membrane and anastomoses with the  medial circumflex femoral artery.   3 Both branches supply the neighbouring muscles, the  posterior branch also gives an acetabular branch which  passes through the acetabular notch to supply the  fat in the acetabular fossa and sends a twig to the  head of the femur along the round ligament (foveolar  artery) (Fig. 4.7).   2 It leaves the femoral triangle by passing backwards  and ends by dividing into ascending and transverse  branches.   3 Ascending branch of medial circumflex femoral  anastomoses with ascending branch of lateral  circumflex femoral and superior gluteal artery to  form "trochanteric anastomoses". This gives  retinacular branches which lie along the retinacula  of capsule of hip joint to supply head of femur.   4 Transverse branch anastomoses with transverse  branch of lateral circumflex femoral, inferior gluteal    • The gracilis muscles is most superficial muscle of  the adductor compartment. This muscle is often  used for transplantation of any damaged muscle.   • Intracapsular fracture of neck of femur causes  damage to the retinacular branches (which supply  head of femur), leading to avascular necrosis of  head of femur.    * Obturator nerve arises from ventral divisions of  ventral primary rami of L2, L3 and L4 segments of  spinal cord; whereas femoral nerve arises from  dorsal divisions of ventral primary rami of the  same segments.   * Adductor magnus and pectineus are two hybrid  or composite muscles   * Since femoral and obturator nerves supply both  the hip joint and knee joint, pain from one joint  may be referred to the other joint.   * Obturator nerve is seen at the medial border of  psoas major muscle, crosses the ala of sacrum to  enter the pelvis. It exits the pelvis through the  obturator foramen to enter the medial aspect of  the thigh.    medial circumflex femoral , branch of profunda  femoris are seen on the medial side of the thigh.    A 50-year-old female complained of pain in her right  knee. She was diagnosed as osteoarthritis and has  been doing physiotherapy. After 2 months, she felt  pain in her right hip as well.   • What is the reason for development of pain in right  hip joint as well?   2. What is nerve supply of hamstring part of adductor  magnus?    Anst The pain in her hip joint is a referred pain from  the knee joint. Obturator nerve supplies both the hip  and knee joints, and the pain from one joint can be  referred to the other. The root value of obturator  nerve is ventral division of ventral primary rami of  L2, L3 and L4 segments of the spinal cord. Femoral  nerve also supplies both these joints. Its root value  is dorsal division of ventral primary rami of L2, L3  and L4 segments of the spinal cord.   4. What is the action of ischial part of adductor  magnus?   The gluteal (Greek rump) region overlies the side and  back of the pelvis, extending from the iliac crest above  to the gluteal fold below. The lower part of the gluteal  region which presents a rounded bulge due to excessive  amount of subcutaneous fat is known as the buttock or  natis. The anterosuperior part of the region seen in a  side view is called the hip. The muscles, nerves and  vessels emerging from pelvis are covered by gluteus  maximus and buttock.   Morphologically, the erect posture of man has led to  extension at the hip and appearance of gluteal fold,  which is a transverse skin crease of the hip joint.  This puts greater responsibility on gluteus maximus  which makes the body erect and maintains it in  erect posture at the hip; this involves raising and  supporting the trunk against gravity. The gluteus  maximus, covering the hip joint is, therefore, one of the  most powerful and bulkiest muscles in man.    1 Buttock is the rounded bulge in the lower part of the  gluteal region. The two buttocks are separated from  each other in the posterior median line by the natal  cleft which begins at the third sacral spine and  deepens inferiorly. The gluteal fold marks the lower  limit of the buttock. Note that the gluteal fold is the  transverse skin crease of the hip joint and that it does  not correspond to the lower border of gluteus  maximus which crosses the fold obliquely  downwards and laterally (Fig. 5.1).   2 Ischial tuberosity is a large bony prominence which  lies deep to the lower border of gluteus maximus  about 5 cm from the median plane and about the  same distance above the gluteal fold. It can be felt    by placing the fingers in the medial part of the gluteal  fold and pressing them upwards.   3 Greater trochanter of femur is a large bony prominence  situated immediately in front of the hollow on the  side of the hip and about a hands breadth below the  tubercle of iliac crest.   4 Iliac crest is a thick curved bony ridge felt in  a groove in the lower margin of the waist. The hands  spanning the waist are often supported by the iliac  crest. The highest point of iliac crest corresponds to  the interval between the spines of the third and  fourth lumbar vertebrae; site of lumbar puncture.   The anterior end of iliac crest is known as the  anterior superior iliac spine. A line drawn from here to  the front of the greater trochanter marks the junction  between gluteal region and the front of thigh.   The posterior end of iliac crest is known as the  posterior superior iliac spine. It lies in the floor of a  dimple about 5 cm from the median plane and at the  level of second sacral spine opposite the middle of  sacroiliac joint.   5 Sacrum lies posteriorly between the two hip bones.  The upper three sacral spines are usually palpable   in the median plane. The second spine, lying between  the two posterior superior iliac spines, is the guide to  the other two spines. The lower part of sacrum and  the coccyx lie in the floor of the natal cleft.   6 Coccyx lies just behind the anus. It is slightly mobile  under pressure.   7 The sacrotuberous ligament lying deep to the lower  border of gluteus maximus can be felt by a firm  pressure between the lower part of sacrum and  ischial tuberosity (Fig. 5.14).   Make a curved incision from spine of second sacral  vertebra (i); along the iliac crest till its tubercle (ii); make  a vertical incision from the second sacral spine  downwards till the natal cleft (iii); taking it further laterally  with downward convexity till the middle of the back of  thigh (iv) (Fig. 5.2). For points v, vi, vii, viii, and ix refer  to Chapters 6, 7, and 9.   Reflect the thick skin and fascia towards the lateral  aspect. The cutaneous nerves and vessels are difficult  to find. Study them from the text. After removing the  deep fascia from gluteus maximus muscle, define the  attachments of this muscle (refer to g ).   It is heavily laden with fat, more so in females, and is  tough and stringy over the ischial tuberosity where it  forms an efficient cushion for supporting the body  weight in the sitting posture. It contains cutaneous  nerves, vessels and lymphatics.   The cutaneous nerves converge on the gluteal region  from all directions (Fig. 5.3a).   1 The upper and anterior part is supplied by the lateral  cutaneous branches of the subcostal T12 and  iliohypogastric LI nerves.   2 The upper and posterior part is supplied by the  posterior primary rami of spinal nerves LI, L2, L3  and SI, S2, S3.   3 The lower and anterior part is supplied by branches  from the posterior division of the lateral cutaneous  nerve of the thigh (L2, L3).   4 The lower and posterior part is supplied by branches  from the posterior cutaneous nerve of the thigh (SI,  S2, S3) and the perforating cutaneous nerve (S2, S3)  (Fig. 5.3b).   The blood supply of the skin and subcutaneous tissue is  derived from perforating branches of the superior and  inferior gluteal arteries.   The lymphatics from the gluteal region drain into the  lateral group of the superficial inguinal lymph nodes.   The deep fascia above and in front of the gluteus  maximus, i.e. over the gluteus medius, is thick, dense,  opaque and pearly white. Over the gluteus maximus,  however, it is thin and transparent. The deep fascia  splits and encloses the gluteus maximus muscle  (Fig. 5.4).   Reflect the gluteus maximus to examine the underlying  structures. For this, identify the lower border of muscle.  Insert a forceps on the deep surface of muscle which is  to be cut from below upwards midway between its origin  and insertion along the course of posterior cutaneous  nerve of thigh. Reflect two parts on either side.   Piriformis is key muscle of the region, define its  margins. Identify the structures above and below this  muscle, most important being the sciatic nerve. Above    Figs 5.3a and b: Cutaneous innervation of the gluteal region: (a) Cutaneous nerves, and (b) root values of the nerves in the four quadrants   piriformis are superior gluteal vessels and nerve. Below  piriformis are inferior gluteal vessels and nerve.   The thickest nerve of the body, sciatic nerve also  enters the gluteal region through the greater sciatic  notch below piriformis muscle.   Pudendal nerve and vessels appear here through  greater sciatic notch and disappear through the lesser  sciatic notch (Fig. 5.14).   Under the lower and medial part of the gluteus  maximus muscle, ischial tuberosity is easily palpable.  Separate the hamstring muscles from the ischial  tuberosity.   Identify long vertical sacrotuberous ligament and  smaller horizontal sacrospinous ligament to demarcate  the greater and lesser sciatic foramina and structures  entering and leaving them. Greater sciatic notch is the  ‘gateway’ of the gluteal region.   Define the borders of the gluteus medius muscle.  Cut through the muscle 5 cm above its insertion into  the greater trochanter of femur. The superior gluteal  vessels and nerve are now exposed which are to be  traced into gluteus minimus and tensor fascia latae.   Reflect gluteus minimus from its origin towards the  insertion to expose the straight and reflected heads of  rectus femoris muscle and the capsule of the hip joint.   These muscles are the gluteus maximus, the gluteus  medius, the gluteus minimus, the piriformis, the  superior and inferior gemelli, the obturator internus  obturator extemus, and quadratus femoris. The tensor  fasciae latae which lies on the lateral side of thigh, just  in front of gluteal region, is also considered here. The  attachments and nerve supply of these muscles are   given in Tables 5.1 and 5.2. Their actions and some other  features are considered below.   9 Insertion of the upper or pubic fibres of the adductor  magnus (Figs 5.5 and 5.6).   This is a large, quadrilateral  powerful muscle covering  mainly the posterior surface of  pelvis (see Fig. 5.4)   It is fan-shaped, and covers the  lateral surface of the pelvis and  hip (see Figs 2.4 and 5.5)   • Posterior part of gluteal surface of ilium  behind the posterior gluteal line   Gluteal surface of ilium between the anterior  and posterior gluteal lines   It is fan-shaped, and is covered and inferior gluteal lines  by the gluteus medius (see Fig. 2.4)   Lies below and parallel to the  posterior border of the gluteus  medius (Fig. 5.5)   • Pelvic surface of the middle three pieces  of the sacrum, by three digitations   Small muscle lying along the upper  border of the tendon of the obturator  internus (see Figs 2.4 and 5.5)   Small muscle lying along the lower  border of the tendon of the obturator  internus (Fig. 5.5)   Fan-shaped, flattened belly lies in  pelvis and the tendon in the gluteal  region (Figs 5.5 and 5.6)    Pelvic surface of obturator membrane  Pelvic surface of the body of the ischium,  ischial tuberosity, ischiopubic rami, and  ilium below the pelvic brim  Obturator fascia   Quadrilateral muscle lying between tuberosity  inferior gemellus and adductor  magnus (Figs 5.5 and 5.6)   Triangular in shape, covers the outer  surface of the anterior wall of the  pelvis (Figs 5.6 and 5.7)    Tensor fasciae latae Anterior 5 cm of the outer lip of the iliac crest   Lies between the gluteal region up to the tubercle of iliac crest  and the front of the thigh (Fig. 5.6)   • The deep fibres of the lower part  of the muscle are inserted into  the gluteal tuberosity (1/4th part)   • The greater part of the muscle is  inserted into the iliotibial tract  (3/4 th part)    Into the greater trochanter of femur,  on oblique ridge on the lateral  surface. The ridge runs downwards  and forwards   Into greater trochanter of femur, on  a ridge on its anterior surface   The rounded tendon is inserted into  the apex of the greater trochanter  of the femur   Blends with tendon of obturator  internus, and gets inserted into  medial surface of greater trochanter  of femur    The tendon of the obturator internus  leaves the pelvis through the lesser  sciatic foramen. Here it bends at a  right angle around the lesser sciatic  notch and runs laterally to be inserted  into the medial surface of the greater  trochanter of the femur    The muscle ends in a tendon which  runs upwards and laterally behind  the neck of the femur to reach the  gluteal region where it is inserted into  the trochanteric fossa (on medial  side of the greater trochanter)    Piriformis  Gemellus superior  Gemellus inferior  Obturator internus  Quadratus femoris  Obturator externus   Inferior gluteal nerve (L5, SI, S2) Chief extensor of the thigh at the hip joint. This   action is very important in rising from a sitting  position. It is essentia! for maintaining the erect  posture. Other actions are:   c. Along with the tensor fasciae latae the muscle  stabilises the knee through the iliotibial tract   It supports both the hip and the knee when these  joints are slightly flexed. It is an antigravity muscle  as well.    Superior gluteal nerve (L4, L5, SI)  Superior gluteal nerve (L4, L5, SI)    The gluteus medius and gluteus minimus are:  Powerful abductors of the thigh. Their anterior fibres  are also medial rotators. However, their most  important action is to maintain the balance of the  body when the opposite foot is off the ground, as in  walking and running. They do this by preventing  the opposite side of the pelvis from tilting  downwards under the influence of gravity.    Ventral rami of SI, S2  Nerve to obturator internus (L5, SI, S2)  Nerve to quadratus femoris (L4, L5, SI)  Nerve to obturator internus (L5, SI, S2)  Nerve to quadratus femoris (L4, L5, SI)  Posterior division of obturator nerve  (L2, L3, L4)    Abductor and medial rotator of thigh and an extensor  of knee joint    Fig. 5.5: Muscles under cover of the gluteus maximus. The upper Fig. 5.6: Scheme of an oblique vertical section showing muscles  and lower borders of this muscle are indicated in thick lines of the gluteal region. Structures under cover of the gluteus maximus   Structures lying deep to the gluteus minimus include  the reflected head of the rectus femoris, and the capsule  of the hip joint.    * Testing gluteus maximus the patient lies prone.  The right hand of physician presses the patient's  right leg downwards. Patient is requested to  extend his hip against resistance provided by the  physician's right hand; while his left hand feels  the contracting gluteus maximus muscle (Fig. 5.7).   * When the gluteus maximus is paralysed as in  muscular dystrophy, the patient cannot stand up  from a sitting posture without support. Such  patients, while trying to stand up, rise gradually,  supporting their hands first on legs and then on  the thighs; they climb on themselves (Fig. 5.8).   * Intramuscular injections are given in the  anterosuperior quadrant of the gluteal region, i.e.  in the glutei medius and minimus, to avoid injury  to large vessels and nerves which pass through  the lower part of this region (Fig. 5.9). Gluteal  region is not the prominence of the buttock only.  It is a very big area over the iliac bone.   * When the glutei medius and minimus (of right side)  are paralysed , the patient cannot walk normally.  He bends or waddles on the right side or paralysed  side to clear the opposite foot, i.e. left, off the  ground. This is known as lurching gait; when  bilateral, it is called waddling gait (Fig. 5.10).   * The normal gait depends on the proper abductor  mechanism at both hips (Fig. 5.11). This mechanism  comprises:   a. The adequate power, provided by the glutei  medius and minimus (Figs 5.12a to c).   b. The fulcrum, formed by a normal relationship  of the head of the femur with the acetabulum.   c. The weight transmitted by the head and neck  of the femur.   * Normally when the body weight is supported on  one limb, the glutei of the supported side raise  the opposite and unsupported side of the pelvis.  However, if the abductor mechanism is defective,  the unsupported side of the pelvis drops, and this  is known as a positive Trendelenburg's sign.   The sign is positive in defects of power, i.e.  paralysis of the glutei medius and minimus; defects  of the fulcrum, i.e. congenital or pathological  dislocation of the hip; and defects of the weight,  i.e. ununited fracture of the neck of femur.   * Gluteus medius and gluteus minimus can be  tested together by doing internal rotation of thigh  against resistance. The person is in supine position  with the hip and knee flexed.   * Gluteus medius, gluteus minimus and tensor  fasciae latae are tested by the abducting lower limb  against resistance. The person in the supine  position and the knee is extended (Fig. 5.13).   Fig. 5.8: Trying to stand up in paralysis of gluteus maximus  muscle    Fig. 5.11: Abductor mechanism at the hip joint  (a) (b) (c)    Figs 5.12a to c: Trendelenburg’s sign, (a) When both feet  are supporting the body weight, the pelvis (anterior superior  iliac spine) on the two sides lies in the same horizontal plane,  (b) when only the right foot is supporting the body weight,  the unsupported side of the pelvis is normally raised by the  opposite gluteal medius and minimus, and (c) if the right glutei  medius and minimus are paralysed, the unsupported left side  of the pelvis drops. This is a positive Trendelenburg’s sign   These two ligaments convert the greater and lesser  sciatic notches of the hip bone into foramina of the same  name.   The sacrotuberous ligament is a long and strong  ligament extending between the medial margin of   Inferior gluteal artery and nerve  Internal pudendal vessels  Pudendal nerve  Nerve to obturator internus  Sacrotuberous ligament  Ischial tuberosity  Gracitis  Adductor magnus  Hamstrings  Posterior cutaneus nerve of thigh    ischial tuberosity and the posterior iliac spines. It forms  the posterolateral boundary of the outlet of the pelvis  (Fig. 5.14).   The sacrospinous ligament is a short, thick, triangular  band situated deep to the sacrotuberous ligament. It is  attached:   The superior gluteal nerve is a branch of the  lumbosacral plexus. It enters the gluteal region through  the greater sciatic foramen, above the piriformis, runs  forwards between the gluteus medius and minimus,  and supplies three muscles, viz., the gluteus medius,  the gluteus minimus and the tensor fasciae latae  (Fig. 5.14).   This is also a branch of the sacral plexus given off in  the pelvis. It enters the gluteal region through the  greater sciatic foramen below the piriformis, and ends  by supplying the gluteus maximus only, to which it is  fully committed (Fig. 5.14).   This is the thickest nerve in the body. It is the main  continuation of the sacral plexus. It enters the gluteal  region through the greater sciatic foramen below the  piriformis, runs downwards between the greater  trochanter and the ischial tuberosity, and enters the  back of the thigh at the lower border of the gluteus  maximus. It does not give any branches in the gluteal  region (Fig. 5.14).    • "Sciatic nerve block" is done by injecting an  anaesthetic agent few cm below the midpoint of  the line joining posterior superior iliac spine and  upper border of greater trochanter.   • Piriformis syndrome occurs if sciatic nerve gets  compressed by piriformis muscle. It leads to pain  in the buttock.   It is a branch of the sacral plexus. It enters the gluteal  region through the greater sciatic foramen, below  the piriformis, and runs downwards medial or posterior  to the sciatic nerve. It continues in the back of the thigh  immediately deep to the deep fascia (Figs 5.6 and 5.14).   a. A perineal branch which crosses the ischial  tuberosity, enters the urogenital triangle of the  perineum, and supplies the skin of the posterior  two-thirds of the scrotum, or labium majus.   b. Gluteal branches which wind upwards round the  lower border of the gluteus maximus, and supply  the skin of the posteroinferior quadrant of the  gluteal region.   This nerve arises from the sacral plexus, enters the  gluteal region through the greater sciatic foramen below  the piriformis, and rims downwards deep to the sciatic  nerve, the obturator intemus and the gemelli. It supplies  the quadratus femoris, the gemellus inferior and the  hip joint (Fig. 5.9).   This is a branch of the sacral plexus. Only a small part of  this nerve is seen in the gluteal region. It enters this region  through the greater sciatic foramen. It then crosses the  apex or lateral end of the sacrospinous ligament, medial  to the internal pudendal vessels. It leaves the gluteal  region by passing into the lesser sciatic foramen through  which it enters the ischioanal fossa (Fig. 5.14).   This is a branch of the sacral plexus. It enters the gluteal  region through the greater sciatic foramen and crosses  the ischial spine, lateral to the internal pudendal vessels,  to re-enter the pelvis. It supplies both the obturator  internus and the gemellus superior muscles.   This is a branch of the sacral plexus. It pierces the lower  part of the sacrotuberous ligament, winds round the  lower border of the gluteus maximus, and supplies the  skin of the posteroinferior quadrant of the gluteal region.   It is a branch of the posterior division of the internal  iliac artery.   It enters the gluteal region through the greater sciatic  foramen passing above the piriformis along with the  superior gluteal nerve. In the foramen, it divides into  superficial and deep branches. The superficial branch  supplies the gluteus maximus (Figs 5.6 and 5.14).    The deep branch subdivides into superior and inferior  branches, which run along the anterior and inferior  gluteal lines respectively, between the gluteus medius  and the gluteus minimus. The superior division ends  at the anterior superior iliac spine by anastomosing with  the ascending branch of the lateral circumflex femoral  artery. The inferior division takes part in the  trochanteric anastomoses.   It is a branch of the anterior division of the internal  iliac artery.   It enters the gluteal region by passing through the  greater sciatic foramen, below the piriformis, along with  the inferior gluteal nerve. It supplies:   1 Muscular branches to gluteus maximus and to all the  muscles deep to it below the piriformis.   2 Cutaneous branches to the buttock and the back of the  thigh (Figs 5.6 and 5.14).   5 An artery to the sciatic nerve, which represents the axis  artery in this region, and may at times be quite large.   6 A coccygeal branch which supplies the area over the  coccyx.   This is a branch of the anterior division of the internal  iliac artery.   It enters the gluteal region through the greater sciatic  foramen (Fig. 5.14). It has a very short course in the  gluteal region.   It crosses the ischial spine and leaves the gluteal  region by passing into the lesser sciatic foramen  through which it reaches the ischioanal fossa.   This is situated near the trochanteric fossa, and  supplies branches to the head of the femur. It is shown  in Flow chart 5.1.   This anastomosis is situated over the upper part of the  back of the femur at the level of the middle of the lesser  trochanter. It is shown in Flow chart 5.2.   STRUCTURES PASSING THROUGH THE GREATER  SCIATIC FORAMEN (GATEWAY OF GLUTEAL REGION)   1 The piriformis, emerging from the pelvis fills the  foramen almost completely. It is the key muscle of  the region.   The inferior division  of the deep branch of  the superior gluteal artery    Medially by the transverse  branch of the medial  circumflex femoral artery    From above by the anastomotic  branch of the inferior gluteal  artery    Laterally by the transverse  branch of the lateral circumflex  femoral artery, (this anastomoses  is a connection between the  internal iliac and femoral arteries)    From below by the ascending  branch of the first perforating  artery, branch of profunda  femoris artery   The last three structures, after a short course in the  gluteal region, enter the lesser sciatic foramen, where  the pudendal nerve and internal pudendal vessels rim  in the pudendal canal.   The upper and lower parts of the foramen are filled  up by the origins of the two gemelli muscles.    • Gluteus maximus is the antigravity, postural  thickest muscle of the body. It contains red fibres.   • Intramuscular injections are given in the upper and  lateral quadrant of the gluteal region.   ■ Greater sciatic notch is the gateway of the gluteal  region   • Sciatic nerve and pudendal nerve do not supply  any structure in the gluteal region.   • Sciatic nerve and its branches supply the hamstring  muscles, muscles of all the three compartments of  the leg and the muscles of the sole.   • Sciatic nerve is accompanied by a thin artery, the  sciatic artery, which is part of the axial artery of  the lower limb.   • Lesser sciatic foramen is the gateway of the  perineal region.   • Sciatic nerve lies on the femur for a very short  distance between lower border of quadratus  femoris and upper border of adductor magnus  muscles. At this site it may get compressed when  one sits on a stool or a bench; leading to harmless  condition, the sleeping foot.    A woman of 30 years complained of pain in her  elbow joints. She also has pain in her calf muscles,  and was advised "Neurobion injections".   Ans: The "neurobion injections" are to be given by  intramuscular route. The site of the injection is upper  lateral quadrant of the gluteal region. Gluteal region    is a big region extending along the iliac crest till the  midline posteriorly. It extends below on the ischial  tuberosity and laterally till the greater trochanter of  femur. The upper lateral quadrant is safe as there are  no important nerve or blood vessel here. The lower  and medial quadrant contains sciatic nerve and must  be avoided. The injection is given in big gluteus  medius muscle and is well absorbed in the circulating  system.    1. Intramuscular injections in upper and lateral  quadrant of gluteal region are given in:   2. Lurching gait is due to paralysis of which two  muscles?   5. Which of the following is not supplied by superior  gluteal nerve?   6. Which muscle is one of the most powerful and  bulkiest muscle in human?   Popliteal (Latin hamstring of knee) fossa is a shallow  diamond shaped depression felt best at the back of knee  joint, when the joint is semi-flexed. It corresponds to  the cubital fossa of the forearm.    1 Lateral and medial condyles of femur and tibia can be  identified easily on the sides and front of the knee.   2 Head of the fibula is a bony prominence situated just  below the posterolateral aspect of the lateral condyle  of tibia.   3 Common peroneal nerve can be palpated against the  posterolateral aspect of the neck of fibula, medial to  the tendon of biceps femoris, by moving the finger  from below upwards.   4 Fibular collateral ligament of the knee joint is felt like  a rounded cord just above the head of the fibula in a  flexed knee.   5 When the knee is flexed against resistance, the  hamstrings can be seen and palpated easily right up  to their insertion. Medially, the rounded tendon of  the semitendinosus lies superficial to the flat tendon  of semimembranosus. In front of these tendons there  is a groove bounded anteriorly by the tendon of  adductor magnus. Laterally, there is the tendon of  biceps femoris. In front of this tendon there is a shallow  groove bounded anteriorly by the iliotibial tract.   6 Pulsations of the popliteal artery can be felt in the  middle of the popliteal fossa by applying deep  pressure.   7 In the lower part of popliteal fossa, two heads of the  gastrocnemius form rounded cushions that merge  inferiorly into the calf.   Make a horizontal incision across the back of thigh at its  junction of upper two-thirds with lower one-third and another  horizontal incision at the back of leg at its junction of upper  one-third and lower two-thirds (v), (vi) (see Fig. 5.2).   Draw a vertical incision joining the midpoints of the  two horizontal incisions made (vii) (see Fig. 5.2). Reflect  the skin and fascia on either side.   Find the cutaneous nerves, e.g. posterior cutaneous  nerve of thigh, posterior division of medial cutaneous  nerve, sural communicating nerve and short saphenous  vein. Cut and clean the deep fascia.   Identify the boundaries and contents of the fossa.  Trace the tibial nerve as it courses through the centre  of the popliteal fossa. Its three delicate articular branches  are given off in the upper part of the fossa, cutaneous  branch in the middle part and muscular branches in lower  part of the fossa.   Common peroneal nerve is lying just medial to the  tendon of biceps femoris muscle. Trace its branches.   Popliteal vein is deep to the tibial nerve and popliteal  artery is the deepest as seen from the back. Trace all  the muscular, cutaneous, genicular and terminal  branches of the popliteal artery (refer to #).   The popliteal fossa is a diamond-shaped depression  lying behind the knee joint, the lower part of the femur,  and the upper part of the tibia.   Superomedially: The semitendinosus and the semi¬  membranosus, supplemented by the gracilis, the  sartorius and the adductor magnus.   The roof of the fossa is formed by deep fascia or  popliteal fascia (Fig. 6.2). The superficial fascia over the  roof contains:   b. Three cutaneous nerves, namely, the branches and  terminal part of the posterior cutaneous nerve of  the thigh, the posterior division of the medial  cutaneous nerve of the thigh, and the peroneal or  sural communicating nerve.   The floor of the popliteal fossa is formed from above  downwards by:   b. The capsule of the knee joint and the oblique  popliteal ligament.   c. The strong popliteal fascia covering the popliteus  muscle (Figs 6.3a and b).   The popliteal vessels and the tibial nerve cross the  fossa vertically, and are arranged one over the other.  The tibial nerve is most superficial; the popliteal vein  lies deep or anterior to tibial nerve; and the popliteal  artery is deepest of all. The artery is crossed posteriorly  by the vein and by the nerve. The relative position of  these structures is as follows.   In the upper part of the fossa, from medial to lateral  side: artery, vein and nerve (A, V, N).   In the middle part, from behind forwards: nerve, vein  and artery (N, V, A).   In the lower part, from medial to lateral side: nerve,  vein and artery (Fig. 6.4) (N, V, A).    Figs 6.3a and b: Floor of the popliteal fossa: (a) Surface view, and (b) vertical sectional view    Fig. 6.4: The arrangement of the main nerves and vessels in Fig. 6.5: Course of the genicular branches of the popliteal artery  the popliteal fossa    The common peroneal nerve crosses the fossa  obliquely from the superior angle to the lateral angle,  along the medial border of the biceps femoris, lying in  the same superficial plane as the tibial nerve.   Popliteal artery is the continuation of the femoral artery.  It begins at the opening in the adductor magnus or  hiatus magnus, i.e. at the junction of middle one-third  with the lower one-third of thigh.   It runs downwards and slightly laterally, to reach  the lower border of the popliteus.   It terminates at the lower border of popliteus by  dividing into the anterior and posterior tibial arteries  (Fig. 6.5).   The popliteal artery is the deepest structure in the  popliteal fossa. It has the following relations.   Anterior or deep to the artery, from above downwards,  there are:   Laterally: Biceps femoris and the lateral condyle of the  femur in the upper part, plantaris and the lateral head  of the gastrocnemius in the lower part.    Medially: Semimembranosus and the medial condyle  of the femur in the upper part. The lower part of the  artery is related to the tibial nerve, the popliteal vein,  and the medial head of the gastrocnemius in the lower  part.   Several large muscular branches are given off. The upper  (two or three) muscular branches supply the adductor  magnus and the hamstrings, and terminate by  anastomosing with the fourth perforating artery. The  lower muscular or sural branches supply the  gastrocnemius, the soleus and the plantaris.   Cutaneous branches arise either directly from the  popliteal artery, or indirectly from its muscular  branches. One cutaneous branch usually accompanies  the small saphenous vein.   Genicular branches are five in number, two superior,  two inferior and one middle. The middle genicular artery  pierces the oblique popliteal ligament of the knee, and  supplies the cruciate ligaments and the synovial  membrane of the knee joint (Fig. 6.5).   The medial and lateral superior genicular arteries wind  round the corresponding sides of the femur  immediately above the corresponding condyle, and  pass deep to the hamstrings.   The medial and lateral inferior genicular arteries wind  round the corresponding tibial condyles, and pass deep  to the collateral ligaments of the knee. All these arteries  reach the front of the knee and take part in forming the  anastomoses around the knee.    • Blood pressure in the lower limb is recorded from  the popliteal artery. In coarctation of the aorta, the  popliteal pressure is lower than the brachial  pressure. Figure 6.6 shows palpation of artery.   • Constant pulsations of the popliteal artery against  the unyielding tendon of the adductor magnus  may cause changes in the vessel wall, leading to  narrowing and occlusion of the artery. Sudden  occlusion of the artery may cause gangrene up to  the knee, but this is usually prevented by the  collateral circulation through the profunda  femoris artery.   • The popliteal artery is fixed to the capsule of the  knee joint by a fibrous band present just above  the femoral condyles. This may be a source of  continuous traction or stretching on the artery,  causing primary thrombosis of the artery in young  subjects.   • When the popliteal artery is affected by  atherosclerosis, the lower part of artery usually  remains patent where grafts can be tried.   • The popliteal artery is more prone to aneurysm  than many other arteries of the body.   It begins at the lower border of the popliteus by the  union of veins accompanying the anterior and posterior  tibial arteries. It is medial to the popliteal artery in the  lower part of the fossa; posterior to the artery in the  middle; and posterolateral to it in the upper part of the  fossa. The vein continues as the femoral vein at the  opening in the adductor magnus. The popliteal vein  receives:   2 The veins corresponding to the branches of the  popliteal artery (Fig. 6.4).   Root value: Ventral divisions of ventral rami of L4, L5,  SI, S2, S3.   This is the larger terminal branch of the sciatic nerve. It  lies superficial or posterior to the popliteal vessels  (Fig. 6.7). It extends from the superior angle to the  inferior angle of the popliteal fossa, crossing the  popliteal vessels from lateral to medial side.   1 Three genicular or articular branches arise in the  upper part of the fossa these are:   a. Superior medial genicular nerve lies above the  medial condyle of femur, deep to the muscles.   b. Middle genicular nerve pierces the posterior part  of the capsule of the knee joint to supply structures  in the intercondylar notch of femur (Fig. 6.7).   c. Inferior medial genicular nerve lies along the  upper border of popliteus and reaches inferior to  the medial condyle of tibia.   2 Cutaneous nerve is called sural which originates in  the middle of the fossa and leaves it at the inferior  angle. It supplies the skin of lower half of back of leg  and whole of lateral border of the foot till the tip of  little toe.   3 Muscular branches arise in the distal part of the fossa  for the lateral and medial heads of gastrocnemius,  soleus, plantaris and popliteus.   The nerve to the popliteus crosses the popliteal  artery, runs downwards and laterally, winds round  the lower border of the popliteus, and supplies it from  its deep (anterior) surface. In addition to the popliteus,  the nerve also supplies the tibialis posterior, the  superior tibiofibular joint, the tibia, the interosseous  membrane, and the inferior tibiofibular joint.    • Most of the muscular branches of tibial nerve arise  from its lateral side except to medial head of  gastrocnemius. So the medial side of the nerve is  safe.   a. Motor loss: Superficial and deep muscles of calf  and intrinsic muscles of sole.   b. Sensory loss: Loss of sensation on whole of sole  of foot, plantar aspect of digits and nail beds  on dorsum of foot.   Root value: Dorsal divisions of ventral rami of L4, L5,  SI, S2.   This is the smaller terminal branch of the sciatic  nerve. It lies in the same superficial plane as the tibial  nerve (Fig. 6.4). It extends from the superior angle of  the fossa to the lateral angle, along the medial border  of the biceps femoris. Continuing downwards and  forwards, it winds round the posterolateral aspect of  the neck of the fibula, pierces the peroneus longus,  and divides into the superficial and deep peroneal  nerves.   a. Lateral cutaneous nerve of the calf descends to  supply the skin of the upper two-thirds of the  lateral side of the leg (Figs 6.4 and 9.1).   b. Sural communicating nerve arises in the upper  part of the fossa. It runs on the posterolateral  aspect of calf and joins the sural nerve (Fig. 6.4).   a. Superior lateral genicular nerve accompanies the  artery of the same name and lies above the lateral  femoral condyle.   b. Inferior lateral genicular nerve also runs with the  artery of the same name to the lateral aspect of  knee joint above the head of fibula (Fig. 6.4).   c. Recurrent genicular nerve arises where common  peroneal nerve divides into superficial and deep    peroneal nerves. It ascends anterior to the knee  joint and supplies tibialis anterior muscle in  addition to the knee joint (see Fig. 8.9).   3 Muscular branches do not arise from this nerve.  However, it may give a branch to the short head of  biceps femoris.   It is a content of the upper half of the popliteal fossa. It  pierces the deep fascia about the middle of the fossa,  and supplies the skin up to the middle of the back of  the leg.   This is the continuation of the posterior division of the  obturator nerve. It runs on the posterior surface of the  popliteal artery, pierces the oblique popliteal ligament,  and supplies the capsule of the knee joint.   These lie deep to the deep fascia near the termination  of the small saphenous vein. They receive afferents from  lateral part of sole, both superficial and deep parts of  back of leg and knee joint. The efferents end in deep  inguinal lymph nodes.    • The common peroneal nerve can be palpated  against the posterolateral side of the neck of the  fibula (see Fig. 8.9). It may be injured in this area. It  is the most frequently injured nerve in the lower  limb (Fig. 6.8). This nerve is relatively unprotected.  It may get entrapped between the attachments of  peroneus longus to the head and shaft of fibula.  Patients present "foot drop " which is usually  painless. There is weakness of dorsiflexion of ankle  and of eversion of the foot. Inversion and plantar  flexion are normal and ankle jerk is intact (Fig. 6.8).   • Popliteal lymph nodes get enlarged in infection on  lateral side of sole /foot. These are lying along the  short saphenous vein. Short saphenous vein pierces  deep fascia to drain into popliteal vein (Fig. 6.9).   1 Anastomoses around the knee joint is a complicated,  arterial network situated around the patella and  around the lower end of the femur and the upper  end of the tibia.   2 The network is divisible into a superficial and a deep  part. The superficial part lies partly in the superficial  fascia around the patella and partly in fat behind the  ligamentum patellae. The deep part lies on the femur   The medial and lateral arteries form longitudinal  anastomoses on each side of the patella. The  longitudinal anastomoses are interconnected to form  transverse anastomoses just above and below the  patella and above the tibial tuberosity.   4 The anastomoses supply the bones taking part in  forming the knee joint, and the capsule and synovial  membrane of the knee joint.   a. The descending genicular branch of femoral  (Fig. 6.10) and its saphenous branch.    • Popliteal artery is used for auscultating while  measuring blood pressure in lower limb   • Short saphenous vein starting from the lateral end  of the dorsal venous arch drains into the popliteal  vein in the popliteal fossa.   » Popliteus muscle unlocks the locked knee joint  before it is flexed by the hamstring muscles.   ■ Tibial nerve runs vertically down the popliteal  fossa. It gives genicular branches in the upper part,  cutaneous branch in the middle part and muscular  branches in the lower part of the fossa.   • Common peroneal nerve as it winds round the  neck of fibula is the most common injured nerve  in the lower limb, resulting in foot drop.    A middle aged person complains of severe weakness  in both the lower limbs. This blood pressure in the  lower limbs was quite less than that of upper limb   auscultating the deeply placed popliteal artery. The  patient has to lie in prone position. The larger cuff is  tied in the thigh. Pressure is raised and released  slowly. Auscultatory sounds are heard on the  popliteal artery.   i.e. narrowing of the aorta so that blood supply to  lower limb decreases causing a fall in blood pressure.  The coarctation needs to be treated surgically.    Which of the following is the thickest nerve of the  body?   1. b 2. d 3. a 4. b 5. a 6. b 7. b 8. a   The posterior compartment of the thigh is also called  the flexor compartment. It is incompletely separated  from the medial compartment by the poorly defined  posterior intermuscular septum. The adductor magnus  is a component of both these compartments.   Give a vertical incision on the back of intact skin left  after the dissections of gluteal region and the popliteal  fossa (viii) (see Fig. 5.2). Reflect the skin and fasciae  on either side. Clean the hamstring muscles and study  their features from the Tables 7.1 and 7.2.   Sciatic nerve was seen in the gluteal region. Identify  its branches in back of thigh to each of the hamstring  muscles including occasionally for the short head of  biceps femoris muscle. Trace the two terminal divisions  of this nerve.   Separate the hamstring muscles to expose the ischial  part of the composite or hybrid adductor magnus  muscle.   Look for insertion of adductor longus, into the linea  aspera of femur.   Trace the profunda femoris vessels behind adductor  longus including its perforating branches (refer to g ).   The skin over the back of the thigh is supplied by  branches from the posterior cutaneous nerve of the  thigh (see Fig. 6.2).   The muscles of the back of the thigh are called the  hamstring muscles. They are the semitendinosus, the    semimembranosus, the long head of the biceps  femoris, and the ischial head of the adductor magnus  (Figs 7.1 to 7.4).   The adductor magnus reaches only up to the  adductor tubercle of the femur, but is included  amongst the hamstrings because the tibial  collateral ligament of the knee joint is,  morphologically, the degenerated tendon of this  muscle. The ligament is attached to medial  epicondyle, two millimeters from the adductor  tubercle.   c. Nerve supply from the tibial part of the sciatic  nerve.   d. The muscles act as flexors of the knee and  extensors of the hip.    * Hamstring muscles lying at the back of the knee  can be accidently or deliberately slashed or cut. If  cut, the person cannot run, as these muscles are  required for extension of the hip and flexion of  the knee, movements essential in walking/  running.   * Hamstrings have variable length. Some persons  cannot touch their toes with fingers while standing  straight as their hamstring muscles are rather  short.   * The inflammation of semimembranous bursa is  called semimembranosus bursitis. The bursa becomes  more prominent during extension of knee, and  disappears during flexion of knee (Fig. 7.5).   It is so named because it is  muscular in upper part and has  a long tendon of insertion. It  lies posteromedially in the thigh,  superficial to the semimembranosus  (Fig. 7.1)   It is so named because it has a  flat tendon of origin. It lies  posteromedially in the thigh, deep  to the semitendinosus (Fig. 7.2)   It has two heads of origin long and  short. It lies posterolaterally in the  thigh (Fig. 7.1)    4. Adductor magnus (see Fig. 4.1)  This is the largest muscle of this  compartment. Because of its  double nerve supply, it is called  a hybrid muscle (Figs 7.3 and 7.4)   From the inferomedial impression on  the upper part of the ischial tuberosity,  in common with the long head of the  biceps femoris (Fig. 7.1)    From the superolateral impression on  the upper part of the ischial tuberosity.    a. Long head: From the inferomedial  impression on the upper part of the  ischial tuberosity; in common with  the semitendinosus, and also from  the lower part of the sacrotuberous  ligament   b. Short head: From the lateral lip of the  linea aspera between the adductor  magnus and the vastus lateralis, from  the upper two-thirds of the lateral  supracondylar line, and from the  lateral intermuscular septum   Into the upper part of the medial surface  of the tibia behind the sartorius and the  gracilis ( see Fig. 4.2b)    Into the groove on the posterior surface  of the medial condyle of the tibia.  Expansions from the tendon form the  oblique popliteal ligament, and the  fascia covering the popliteus (see Fig. 6.3a)   The tendon is either folded around,  by the fibular collateral ligament.   It is inserted into the head of the fibula  in front of its apex or styloid process  (see Fig. 2.24)   b. Short head, by common peroneal part of  sciatic nerve (L5, SI, S2)   Double nerve supply: Adductor part by  posterior division of obturator nerve  Hamstring part by tibial part of sciatic nerve    Chief flexor of the knee and medial  rotator of the leg in semiflexed knee.  Weak extensor of the hip   Chief flexor of the knee and medial  rotator of the leg in semiflexed knee.  Weak extensor of the hip   Chief flexor of the knee and lateral  rotator of leg in semiflexed knee. Weak  extensor of the hip   Adductor part causes adduction of thigh;  Ischial part helps in extension of  hip and flexion of knee   The sciatic nerve is the thickest nerve in the body. In its  upper part, it forms a band about 2 cm wide. It begins  in the pelvis and terminates at the superior angle of  the popliteal fossa by dividing into the tibial and  common peroneal nerves.   This is the largest branch of the sacral plexus. Its root  value is L4, L5, SI, S2, S3. It is made up of two parts,  the tibial part and the common peroneal part. The tibial  part is formed by the ventral divisions of the anterior  primary rami of L4, L5, SI, S2, S3. The common peroneal   Sciatic nerve lying  at the junction  of quadratus femoris  and adductor magnus    Fig. 7.3: Adductor magnus and quadratus femoris muscles with  terminal branches of sciatic nerve    Fig. 7.4 : Muscles of back of the thigh. Cross-section above the  adductor tubercle    part is formed by the dorsal divisions of the anterior  primary rami of L4, L5, SI, S2 (Fig. 7.6).   1 In the pelvis: The nerve lies in front of the piriformis,  under cover of its fascia.   2 In the gluteal region: The sciatic nerve enters the  gluteal region through the greater sciatic foramen    Fig. 7.6 : Scheme to show the sacral plexus and its branches   3 In the thigh: The sciatic nerve enters the back of the  thigh at the lower border of the gluteus maximus. It  runs vertically downwards up to the superior angle  of the popliteal fossa, at the junction of the upper  two-thirds and lower one-third of the thigh, where  it terminates by dividing into the tibial and the  common peroneal nerves. It has the following  relations in the thigh:   Superficial or posterior: The sciatic nerve is crossed by  the long head of the biceps femoris (Fig. 7.7).    below the piriformis. It runs downwards with a slight  lateral convexity, passing between the ischial  tuberosity and the greater trochanter. It has the  following relations in the gluteal region.   Deep or anterior: The nerve lies on the adductor  magnus (Fig. 7.3).   The sciatic nerve is accompanied by a small  companion artery which is a branch of the inferior  gluteal artery. The artery rims along the sciatic nerve  for some distance before sinking into its substance.   1 Articular branches to the hip joint arise in the gluteal  region.   2 Muscular branches: The tibial part of the sciatic nerve  supplies the semitendinosus, the semimembranosus,  the long head of the biceps femoris, and the ischial  head of the adductor magnus from its medial side.  The common peroneal part supplies only the short head  of the biceps femoris.    • Testing the hamstring muscles hamstring muscles  can be tested by requesting the patient to flex the  knee against resistance in prone position (Fig. 7.8).   • Sciatic nerve lies on quadratus femoris and  adductor magnus. Between the thin borders of  these two muscles the nerve lies for a short distance  on the femur. When a person sits on the edge of a  hard table/chair, the nerve gets compressed  between the edge of table and femur. It results in  numbness of lower limb. But the sensations come  back when foot is hit on the ground a few times  and is called sleeping foot (Fig. 7.3).   • Shooting pain along the cutaneous distribution of  the sciatic nerve and its terminal branches, chiefly  the common peroneal, is known as sciatica . Pain  usually begins in the gluteal region, and radiates  along the back of the thigh, and the lateral side of  the leg, to the dorsum of the foot.   This is usually due to compression of one or more  nerve roots forming the sciatic nerve. The cause  maybe disc prolapse, neuritis, etc. (Fig. 7.9).   • The semimembranosus bursa may get inflamed.  The condition is called semimembranosus bursitis  (Fig- 7.5).   • The sciatic nerve may be injured by penetrating  wounds, dislocation of the hip. This results in loss  of all movements below the knee with foot drop;  sensory loss on the back of the thigh, the whole of  the leg, and the foot except the area innervated by  the saphenous nerve (Fig. 7.10).   • Motor loss includes loss of hamstring muscles, loss  of dorsiflexors, plantarflexors, evertors and  muscles of sole (Fig. 7.11)   The arteries on the back of the thigh are terminal parts  of the branches of the profunda femoris. The lateral   circumflex femoral branch of the profunda femoris  divides into ascending, transverse and descending  branches.   The medial circumflex femoral artery gives  acetabular branch and then divides into ascending and  transverse branches (Figs 7.12a and b).   The main supply to the back of the thigh is through  the perforating branches of the profunda femoris. These  are described below.   The profunda femoris artery gives off four perforating  arteries. They arise on the front of the thigh. They then  pass through the adductor magnus and wind round  the back of the femur, piercing the aponeurotic origins  of other muscles attached to the linea aspera. They  ultimately end in the vastus lateralis (Fig. 7.13).   The first perforating artery arises just above, or on  the upper border of the adductor brevis, the second in  front of the adductor brevis, the third immediately  below the adductor brevis, and the fourth is the  termination of the profunda femoris artery (Figs 7.12a  and b). The perforating arteries give off muscular  branches. They also give off cutaneous and anastomotic  branches. The second perforating artery, gives off the  nutrient artery to the femur.   At least two distinct chains of anastomoses can be made  out in the back of the thigh. One lies partly on the  surface of the adductor magnus and partly in its  substance. The other lies close to the linea aspera of  femur. These longitudinal anastomotic chains are  formed by the branches of internal iliac, the femoral  and popliteal arteries. Thus from above downwards:   1 The gluteal arteries anastomose with each other and  with the circumflex femoral arteries (see How chart 5.1).    Figs 7.12a and b: Origin and course of the profunda femoris artery: (a) Surface view, and (b) sagittal sectional view. Note that the  femoral and profunda vessels straddle the adductor longus   Internal iliac artery  Superior gluteal artery  Inferior gluteal artery  Cruciate anastomosis  1st perforating artery  2nd perforating artery  3rd perforating artery  4th perforating artery    2 The circumflex femorals anastomose with the first  perforating artery (cruciate anastomoses) (Fig. 7.14  and see Flow chart 5.2).   4 The fourth perforating artery anastomoses with the  upper muscular branches of the popliteal artery.   Another anastomosis is found on the sciatic nerve.  This is formed by the companion artery of the sciatic  nerve and the perforating arteries.   These longitudinal anastomoses provide an  alternative route of blood supply to the lower limb,  bypassing the external iliac and femoral arteries.   • Thin artery accompanying sciatic nerve is part of  the axial artery of lower limb.    A 26-year-old woman complained of severe pain in  the back of her right thigh and leg.   • Which nerve is involved and what is its root value?   • What is straight leg raising test? If done on this  patient, why does it cause pain?   Ans: The nerve involved is sciatic nerve. Its root  value is ventral rami of L4, L5, SI, S2, S3 segments  of spinal cord. The pain on the back of thigh indicates  compression of the roots of sciatic and radiating pain  along cutaneous branches of tibial and common  peroneal nerves.   The patient lies supine on the bed. The affected leg  is extended at both hip and knee joints. Then it is  raised up from the bed by holding the foot. As the  nerve is stretched, it causes severe pain.   3. Compression of which nerve leads to numbness of  lower limb    c. The muscle act as flexor of knee and extensor of  hip   a. Sacral plexus b. Lumbar plexus  c. Cervical plexus d. Brachial plexus   7. Tibial collateral ligament of knee is the morpho¬  logical continuation of:   1. a 2. a 3. a 4. b 5. a 6. a 7. a    Front, Lateral and Medial Sides of  Leg and Dorsum of Foot   The great saphenous vein starts on the medial side of  the dorsum of the foot and runs up just anterior to the  medial malleolus, where it can be "slit open" for  transfusion purposes. Dorsalis pedis artery, the distal  continuation of the anterior tibial artery, is used for  palpation in some clinical conditions. The dorsiflexors  of foot supplied by deep peroneal nerve lie in the  anterior compartment of leg. Tibialis anterior is an  invertor of the foot as well. The two big evertors of the  foot with superficial peroneal nerve are placed in the  lateral compartment of the leg. The tendons of all these  muscles are retained in position by two extensor and  two peroneal retinacula. The three muscles inserted on  the upper medial surface of tibia stabilise the pelvis on  the thigh and leg ( see Fig. 4.2b).    1 Medial and lateral condyles of tibia are felt better in a  flexed knee with the thigh flexed and laterally  rotated (Fig. 8.1).   2 Tibial tuberosity is a bony prominence on the front  of the upper part of tibia, 2.5 cm distal to the knee  joint line passing through the upper margins of the  tibial condyles. The tuberosity provides attachment  to ligamentum patellae above, and is continuous  with the shin below.   3 Head of the fibula lies posterolaterally at the level of  tibial tuberosity. It serves as a guide to common  peroneal nerve which winds around the  posterolateral aspect of the neck of fibula.   4 Shin is the subcutaneous anterior border of tibia. It  is sinuously curved and extends from the tibial  tuberosity to the anterior margin of the medial  malleolus. It is better defined in the upper part than  in the lower part.    Fig. 8.1 : Landmarks on leg and foot with superficial veins on  the front    5 Medial surface of tibia is subcutaneous, except in the  uppermost part where it is crossed by the tendons  of sartorius, gracilis and semitendinosus. Great  saphenous vein crosses lower one-third of the  surface, running obliquely upwards and backwards  from the anterior border of medial malleolus.   6 Medial border of tibia is palpable throughout its  whole extent. The saphenous nerve and great  saphenous vein run partly along it.   7 Gastrocnemius and the underlying soleus form the  fleshy prominence of the calf These muscles become    FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT   prominent when heel is raised as standing on toes.  Tendocalcaneus is the strong, thick tendon of these  muscles; it is attached below to the posterior surface  of calcaneum.   8 Medial malleolus is the bony prominence on the  medial side of ankle. It is formed by a downwards  projection from the medial surface of the lower end  of tibia.   9 Lateral malleolus is the bony prominence on the  lateral side of ankle. It is formed by the lower end  of fibula. It is larger but narrower than the medial  malleolus, and its tip is 0.5 cm below that of the  medial malleolus. The posterior borders of two  malleoli are in the same coronal plane, but the  anterior border of lateral malleolus is about 1.5 cm  behind that of the medial malleolus.   10 Peroneal trochlea , when present, is felt as a little  prominence about a finger-breadth below the lateral  malleolus. Peroneus brevis passes above and the  peroneus longus below the trochlea.   11 Sustentaculum tali can be felt about a thumb-breadth  below the medial malleolus.   12 Tuberosity of navicular bone is a low bony prominence  felt 2.5 to 3.75 cm anteroinferior to the medial  malleolus, about midway between the back of the  heel and root of the big toe.   13 Head of the talus lies above the line joining the  sustentaculum tali and tuberosity of navicular bone.   14 Tuberosity of the base of fifth metatarsal bone is the most  prominent landmark on the lateral border of the  foot. It lies midway between the point of the heel  and the root of the little toe.   15 Posterior tibial artery pulsations can be felt against  calcaneum about 2 cm below and behind the medial  malleolus (see Fig. 9.9).   16 Dorsalis pedis artery pulsations can be felt best on  the dorsum of foot about 5 cm distal to the malleoli,  lateral to the tendon of extensor hallucis longus,  over the intermediate cuneiform bone (Fig. 8.11).   17 Tendon of tibialis anterior becomes prominent on  active inversion of the foot, passing downwards  and medially across the medial part of the anterior  surface of ankle.   18 Tendon of extensor hallucis longus becomes prominent  when the foot is dorsiflexed.   19 Extensor digitorum brevis produces an elevation on  the lateral part of the dorsum of foot when the toes  are dorsiflexed or extended (Fig. 8.7).   20 First metatarsophalangeal joint lies a little in front of  the centre of the ball of big toe. The other  metatarsophalangeal joints are placed about 2.5 cm  behind the webs of the toes.   1. Make a horizontal incision across the leg at its  junction with foot ( see Fig. 3.1).   2. Provide a vertical incision up from the centre of  incision (1) to the middle of incision drawn just below  the level of tibial tuberosity.   3. Carry this vertical incision on to the dorsum of foot  till the middle of the second toe.   Reflect the skin on both the sides. Look for various  veins and cutaneous nerves in the leg and foot  according to the description given in the text  (refer to #).   The superficial fascia of the front of the leg and the   1 The dorsal venous arch lies on the dorsum of the foot  over the proximal parts of the metatarsal bones. It  receives four dorsal metatarsal veins each of which  is formed by the union of two dorsal digital veins  (Fig. 8.1).   2 The great or long saphenous vein is formed by the union  of the medial end of the dorsal venous arch with the  medial marginal vein which drains the medial side of  the great toe. It passes upwards in front of the medial  malleolus, crosses the lower one-third of the medial  surface of tibia obliquely, and runs along its medial  border to reach the back of the knee. The saphenous  nerve runs in front of the great saphenous vein.   3 The small or short saphenous vein is formed by the  union of the lateral end of the dorsal venous arch  with the lateral marginal vein, draining the lateral  side of the little toe. It passes upwards behind the  lateral malleolus to reach the back of the leg. The  sural nerve accompanies the small saphenous vein.  Both saphenous veins are connected to the deep veins   1 The infrapatellar branch of the saphenous nerve pierces  the sartorius and the deep fascia on the medial side  of the knee, curves downwards and forwards, and  supplies the skin over the ligamentum patellae  (Fig. 8.2).   2 The saphenous nerve is a branch of the posterior  division of the femoral nerve. It pierces the deep  fascia on the medial side of the knee between the    Fig. 8.2 : Cutaneous nerves on the front of the leg and dorsum  of foot    sartorius and the gracilis, and runs downwards in  front of the great saphenous vein. It supplies the skin  of the medial side of the leg and the medial border  of the foot up to the ball of the great toe.   3 The lateral cutaneous nerve of the calf is a branch of the  common peroneal nerve. It pierces the deep fascia  over the lateral head of the gastrocnemius, and  descends to supply the skin of the upper two-thirds  of the lateral side of the leg (Fig. 8.2).   4 The superficial peroneal nerve is a branch of the  common peroneal nerve. It arises on the lateral side  of the neck of the fibula deep to the fibres of the  peroneus longus. It descends between the peroneal  muscles, pierces the deep fascia at the junction of  the upper two-thirds and lower one-third of the  lateral side of the leg, and divides into medial and  lateral branches. These branches supply the  following area:   a. The skin over the lower one-third of the lateral  side of the leg (Fig. 8.2).   b. The skin over the entire dorsum of the foot with  the exception of the following areas.   ii. Medial border up to the base of the great toe,  supplied by the saphenous nerve.   iii. Cleft between the first and second toes,  supplied by the deep peroneal nerve.   5 The sural nerve is a branch of the tibial nerve. It arises  in the middle of the popliteal fossa. It runs vertically  downwards, pierces the deep fascia in the middle of  the back of leg, accompanies the small saphenous    vein, and supplies the skin of the lower half of the  back of leg and of the whole of the lateral border of  the foot up to the tip of the little toe (see Fig. 9.1).   6 The deep peroneal nerve terminates by supplying the  skin adjoining the cleft between the first and second  toes.   7 The digital branches of the medial and lateral plantar  nerves curve upwards and supply the distal parts of  the dorsum of the toes. Medial plantar nerve supplies  medial 3Vi toes; lateral plantar nerve supplies lateral  lVi toes.    Saphenous nerve may be subjected to entrapment  neuropathy as it leaves the adductor canal, leading  to pain in the area of its supply.   Underlying the superficial fascia is the dense deep fascia  of leg. Divide this fascia longitudinally as it stretches  between tibia and fibula.   Expose the superior extensor retinaculum 5 cm  above the ankle joint and the inferior extensor  retinaculum in front of the ankle joint.   1 In the leg, tibia and fibula are partly subcutaneous,  the most notable being the medial surface of the tibia,  and the malleoli. Over these subcutaneous areas, the  deep fascia is replaced by periosteum.   2 Extensions of deep fascia form intermuscular septa  that divide the leg into compartments (Fig. 8.3).   The anterior and posterior intermuscular septa are  attached to the anterior and posterior borders of the  fibula. They divide the leg into three compartments:  anterior, lateral, and posterior. The posterior  compartment is subdivided into superficial,  intermediate and deep parts by superficial and deep  transverse fascial septa.   3 Around the ankle, the deep fascia is thickened to form  bands called retinacula. These are so called because  they retain tendons in place. On the front of the ankle  there are the superior and inferior extensor retinacula.  Laterally, there are the superior and inferior peroneal  retinacula. Posteromedially, there is the flexor  retinaculum. The extensor retinacula are described  below. The peroneal retinacula are considered with  the lateral compartment of the leg and the flexor  retinaculum with the posterior compartment.   FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT    Tibialis anterior muscle  Extensor hallucis longus muscle  Extensor digitorum longus muscle  Superficial peroneal nerve  Anterior intermuscular septum  Peroneus longus muscle   Peroneus brevis muscle  Fibula  Peroneus vessels  Deep transverse intermuscular septum  Superficial transverse intermuscular septum    Anterior tibial artery with vena  comitantes and deep peroneal nerve  Posterior tibial artery with vena  comitantes and tibial nerve  Interosseous membrane    Fig. 8.3 : Transverse section through the middle of the leg showing the intermuscular septa and the arrangement of structures in the  anterior and lateral compartments   Medially , it is attached to the lower part of the anterior  border of the tibia, and laterally to the lower part of  the anterior border of the fibula forming the anterior  boundary of the elongated triangular area just above  the lateral malleolus (Fig. 8.4).   This is a Y-shaped band of deep fascia, situated in front  of the ankle joint and over the posterior part of the  dorsum of the foot. The stem of the Y lies laterally, and  the upper and lower bands, medially (Fig. 8.4).   1 The stem is attached to the anterior non-articular part  of the superior surface of the calcaneum, in front of  the sulcus calcanei.    2 The upper band passes upwards and medially, and is  attached to the anterior border of the medial  malleolus.   3 The lower band passes downwards and medially and  is attached to the plantar aponeurosis.    Anterior tibial compartment syndrome/fresher's  syndrome: The muscles of anterior compartment of  leg get pain because of too much sudden exercise.  The muscles are tender to touch.    Fig. 8.4 : Tendons, vessels and nerves related to the extensor  retinacula   Identify the muscles of anterior compartment of leg as  these are lying close together on the lateral surface of  tibia, adjoining interosseous membrane and medial  surface of fibula.   Trace their tendons deep to the two retinacula on  the dorsum of foot till their insertion. Learn about these  muscles given in Tables 8.1 and 8.2.   Look for anterior tibial artery and accompanying deep  peroneal nerve as these lie on the upper part of  interosseous membrane of leg. Study their course,  relations and branches.   The muscles of the anterior compartment of the leg are  the tibialis anterior, the extensor hallucis longus, the  extensor digitorum longus and the peroneus tertius  (Fig. 8.5).   These muscles are tested by palpation on the front of leg  and requesting the patient to dorsiflex the foot (Fig. 8.6).   The attachments of these muscles are given in  Tables 8.1 and 8.2.   This is the main artery of the anterior compartment of  the leg (Fig. 8.8). The blood supply to the anterior  compartment of the leg is reinforced by the perforating  branch of the peroneal artery, the size of which is  inversely proportional to that of the anterior tibial artery.   The anterior tibial artery is the smaller terminal branch  of the popliteal artery.   It begins on the back of the leg at the lower border of  the popliteus, opposite the tibial tuberosity.   It enters the anterior compartment of the leg by  passing forwards close to the fibula, through an opening  in the upper part of the interosseous membrane.    Fig. 8.6 : How to test the dorsiflexors of the ankle joint   In the anterior compartment, it runs vertically  downwards to a point midway between the two  malleoli where it changes its name to become the  dorsalis pedis artery.    In the upper one-third of the leg, the artery lies between  the tibialis anterior and the extensor digitorum longus  (Fig.8.5).   In the middle one-third it lies between the tibialis  anterior and the extensor hallucis longus (Fig. 8.3).   In the lower one-third it lies between the extensor  hallucis longus and the extensor digitorum longus. In  understanding these relations note that the artery is  crossed from lateral to medial side by the tendon of the  extensor hallucis longus (Fig. 8.4).   The artery is accompanied by the venae comitantes.  The deep peroneal nerve is lateral to it in its upper  and lower thirds, and anterior to it in its middle one-  third (Fig. 8.4).   2 Anastomotic branches are given to the knee and ankle.  The anterior and posterior tibial recurrent branches take  part in the anastomoses round the knee joint  (see Fig. 6.10). The anterior medial malleolar and anterior  lateral malleolar branches take part in the anastomoses  round the ankle joint or malleolar networks (Fig. 8.8).  The lateral malleolar network lies just below the lateral   FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT    Table 8.1: Muscles of the anterior compartment of the leg and dorsum of foot   It has a spindle-shaped belly  with multipennate fibres  (see Fig. 2.27)   It is a separated part of the  extensor digitorum longus,  and may be regarded as its  fifth tendon. It may be absent   This is a small muscle  situated on the lateral part  of the dorsum of foot, deep  to the tendons of the  extensor digitorum longus  (Fig. 8.7)   b. Upper two-thirds of the lateral  surface of the shaft of the tibia   a. Posterior half of the middle 2/4th of the  medial surface of the shaft of the fibula,  medial to the extensor digitorum longus   b. Whole of upper one-fourth and anterior half  of middle 2/4th of the medial surface of the  shaft of the fibula    a. Lower one-fourth of the medial surface of  the shaft of the fibula   The muscle arises from anterior part of the  superior surface of the calcaneum   Inferomedial surface of the medial  cuneiform and the adjoining part of the  base first metatarsal bone   Dorsal surface of the base of the distal  phalanx of the big toe    It divides into four tendons for the lateral  four toes. The tendons of 2nd, 3rd and 4th  digits are joined on the lateral side by  tendon of the extensor digitorum brevis, and  forms the dorsal digital expansion. It is  inserted on the bases of the middle and  distal phalanges (Fig. 8.7)   Medial part of the dorsal surface of the base  of the fifth metatarsal bone    The muscle divides into four tendons for  the medial four toes. The medial most part  of the muscle, which is distinct, is known  as the extensor hallucis brevis.   The extensor hallucis brevis is inserted into  the dorsal surface of the base of the  proximal phalanx of the great toe. The  lateral three tendons join the lateral sides  of the tendons of the extensor digitorum  longus to form the dorsal digital expansion  for the second, third and fourth toes    Note: The above muscles also take origin from the deep surface of the deep fascia, and from adjoining intermuscular septa.   d. Maintains medial longitudinal arch of the foot  Dorsiflexor of foot and extends metatarsophalangeal and inter-  phalangeal joints of big toe   Dorsiflexor of foot. Extends metatarsophalangeal, proximal and distal  interphalangeal joints of 2nd-5th toes  Dorsiflexor of foot and evertor of foot   Medial tendon known as extensor hallucis brevis, extends meta¬  tarsophalangeal joint of big toe. The other three lateral tendons  extend the metatarsophalangeal and interphalangeal joints of 2nd,  3rd and 4th toes particularly in a dorsiflexed foot   Deep peroneal nerve is the nerve of the anterior  compartment of the leg and the dorsum of the foot. This    is one of the two terminal branches of common peroneal  nerve. It corresponds to the posterior interosseous nerve  of the forearm.    Fig. 8.7: Joint tendons of extensor digitorum brevis and extensor  digitorum longus in 2nd, 3rd and 4th toes    Fig. 8.8 : Arteries on the front of the leg and dorsum of the foot   Fig. 8.9 : Common peroneal nerve and its terminal branches  the peroneal retinacula also seen   It enters the anterior compartment by piercing the  anterior intermuscular septum. It then pierces the  extensor digitorum longus and comes to lie next to the  anterior tibial artery (Fig. 8.3).   In the leg, it accompanies the anterior tibial artery  and has similar relations.   The nerve ends on the dorsum of the foot, close to  the ankle joint, by dividing into the lateral and medial  terminal branches (Fig. 8.4).   The lateral terminal branch turns laterally and ends in  a pseudoganglion deep to the extensor digitorum brevis.  Branches proceed from the pseudoganglion and supply  the extensor digitorum brevis and the tarsal joints.   The medial terminal branch ends by supplying the skin  adjoining the first interdigital cleft and the proximal  joints of the big toe (Fig. 8.2).   Deep peroneal nerve is one of the terminal branches of  common peroneal nerve. It begins on the lateral side of  the neck of the fibula (Fig. 8.9).   1 Four muscles of the anterior compartment of the leg  (Figs 8.3 and 8.5).   2 The extensor digitorum brevis on the dorsum of the foot.    FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT    A cutaneous branch supplies adjacent sides of the first  and second toes (Fig. 8.2).   Articular branches supply the ankle joint, the tarsal  joints, the tarsometatarsal and metatarsophalangeal  joints of the big toe.    Paralysis of the muscles of the anterior compartment  of the leg due to injury to deep peroneal nerve  results in loss of the power of dorsiflexion of the  foot. As a result the foot is plantar flexed. The  condition is called foot drop . This is usually caused  by injury or disease of the common peroneal nerve  due to trauma, leprosy or peripheral neuritis  (Fig. 8.10). Sensory loss is confined to first  interdigital cleft.   Fig. 8.10: Foot drop on the right side. Sensory loss in the  first interdigital cleft   Identify the small muscle extensor digitorum brevis  situated on the lateral side of dorsum of foot. Its tendons  are deep to the tendons of extensor digitorum longus.  Its most medial tendon in called extensor hallucis brevis  (Fig. 8.7). Dissect the dorsalis pedis artery and its  branches on the dorsum of the foot.   This is the chief palpable artery of the dorsum of the  foot (Fig. 8.8). It is commonly palpated in patients with    vaso-occlusive diseases of the lower limb. It is a  continuation of the anterior tibial artery on to the  dorsum of the foot (Figs 8.4 and 8.11).   The artery begins in front of the ankle between the  two malleoli. It passes forwards along the medial side  of the dorsum of the foot to reach the proximal end  of the first intermetatarsal space. Here it dips  downwards between the two heads of the first dorsal  interosseous muscle, and ends in the sole by  completing the plantar arterial arch (Fig. 8.8).   2 Extensor hallucis brevis, which crosses the artery  from the lateral to medial side.   2 The talus, navicular and intermediate cuneiform  bones and the ligaments connecting them.   1 The lateral tarsal artery is larger than the medial and  arises over the navicular bone. It passes deep to the  extensor digitorum brevis, supplies this muscle and  neighbouring tarsal joints, and ends in the lateral  malleolar network.   2 The medial tarsal branches are two to three small twigs  which join the medial malleolar network.   3 The arcuate artery is a large branch that arises  opposite the medial cuneiform bone. It runs laterally  over the bases of the metatarsal bones, deep to the  tendons of the extensor digitorum longus and the  extensor digitorum brevis, and ends by  anastomosing with the lateral tarsal and lateral  plantar arteries. It gives off the second, third and fourth  dorsal metatarsal arteries (Fig. 8.8) each of which  divides into dorsal digital branches for adjoining  toes. The dorsal metatarsal arteries are joined by pro¬  ximal and distal perforating arteries from the sole.    4 The first dorsal metatarsal artery arises just before the  dorsalis pedis artery dips into the sole. It gives a  branch to the medial side of the big toe, and divides  into dorsal digital branches for adjacent sides of the  first and second toes.    Pulsations of the dorsalis pedis artery are easily felt  between the tendons of the extensor hallucis longus  and the first tendon of the extensor digitorum longus.  It must be remembered, however, that the dorsalis  pedis artery is congenitally absent in about 14% of  subjects (Fig. 8.11).   Reflect the lateral skin flap of leg further laterally till  peroneal muscles are seen. Divide the deep fascia  longitudinally over the peroneal muscles. Clean the  superior and inferior peroneal retinacula situated just  above and below the lateral malleolus.   Identify the peroneus longus and peroneus brevis  muscles. Trace their tendons through the retinacula  towards their insertion. Study the deep fascia and  peroneal muscles (refer to #).   The lateral or peroneal compartment of the leg is  bounded anteriorly by the anterior intermuscular  septum, posteriorly by the posterior intermuscular  septum, medially by the lateral surface of the fibula, and  laterally by the deep fascia (Fig. 8.3).    Vessels: The arterial supply is derived from the branches  of the peroneal artery which reach the lateral  compartment by piercing the flexor hallucis longus and  the posterior intermuscular septum. The veins drain  into the small saphenous vein.   The superior peroneal retinaculum is a thickened band of  deep fascia situated just behind the lateral malleolus.  It holds the peroneal tendons in place against the back  of the lateral malleolus. It is attached anteriorly to the  posterior margin of the lateral malleolus, and  posteriorly to the lateral surface of the calcaneum and  to the superficial transverse fascial septum of the leg  (Fig. 8.9).   The inferior peroneal retinaculum is a thickened band  of deep fascia situated anteroinferior to the lateral  malleolus. Superiorly, it is attached to the anterior part  of the superior surface of the calcaneum, where it  becomes continuous with the stem of the inferior  extensor retinaculum. Interiorly, it is attached to the  lateral surface of the calcaneum. A septum attached to  the peroneal tubercle or trochlea divides the space deep  to the retinaculum into two parts.   The peroneal retinacula hold the tendons of the  peroneus longus and brevis in place.   Under the superior retinaculum the two tendons are  lodged in a single compartment, and are surrounded  by a common synovial sheath.   Under the inferior retinaculum each tendon lies in a  separate compartment. The tendon of the peroneus  brevis lies in the superior compartment and that of the  peroneus longus in the inferior compartment. Here each  tendon is enclosed in a separate extension of the  synovial sheath (Fig. 8.9).    Tenosynovitis of peronei tendon is the inflammation  of the tendon sheaths of the peroneal muscles. If  superior peroneal retinaculum is torn, the tendons  can get dislocated to front of lateral malleolus.   These are the peroneus longus and the peroneus brevis  (Fig. 8.12). Their attachments are given in Tables 8.3  and 8.4.    Paralysis of peroneus brevis and peroneus longus  occurs due to injury to superficial peroneal nerve.  The foot cannot be everted at subtalar joint.    FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT   Carefully look for common peroneal nerve in relation to  the neck of fibula.   Superficial peroneal nerve, one of the terminal  branches of common peroneal nerve supplies both the  peroneus longus and brevis muscles and in lower one-  third of leg becomes cutaneous to supply most of the  dorsum of foot.   Superficial peroneal nerve (Fig. 8.9) is the main nerve  of the lateral compartment of the leg.   It is a smaller terminal branch of the common peroneal  nerve.   The nerve begins on the lateral side of neck of fibula,  runs through the peroneal muscles and becomes  superficial at the junction of upper two-thirds and lower  one-third of leg.   It begins on the lateral side of the neck of the fibula,  under cover of the upper fibres of the peroneus longus.   In the upper one-third of the leg, it descends through  the substance of the peroneus longus. In the middle one-  third, it first descends for a short distance between the  peroneus longus and brevis muscles, reaches the  anterior border of the peroneus brevis , and then descends  in a groove between the peroneus brevis and the extensor  digitorum longus under cover of deep fascia.   At the junction of the upper two-thirds and lower  one-third of the leg, it pierces the deep fascia to become  superficial. It divides into a medial and a lateral branch  which descend into the foot (Fig. 8.2).   Cutaneous branches: Through its terminal branches,  the superficial peroneal nerve supplies the lower one-  third of the lateral side of the leg and the greater part  of the dorsum of the foot, except for the territories   b. Upper one-third, and posterior  half of the middle one-third of  the lateral surface of the shaft  of the fibula    The tendon passes deep to the peroneal retinacula, runs  through a tunnel in the cuboid, and is inserted into (a) the  lateral side of the base of the first metatarsal bone and (b) the  adjoining part of the medial cuneiform bone. The tendon  changes its direction below the lateral malleolus and again  on the cuboid bone. A sesamoid is present in the tendon in the  latter situation    a. Anterior half of the middle  one-third and whole of the  lower one-third of the lateral  surface of the shaft of fibula    The tendon passes deep to the peroneal retinacula, and is  inserted into the lateral side of the base of the fifth metatarsal  bone (see Fig. 2.44)   b. Maintain lateral longitudinal arch and transverse arch of the foot  Peroneus longus and tibialis anterior are inserted into the same two  bones, the two together form a ‘stirrup’ beneath the middle of the sole.  The presence of the sling keeps the middle of foot pulled up and  prevents flattening of its arches.    supplied by the saphenous, sural, deep peroneal nerves  and plantar nerves (Fig. 8.2).   The medial branch crosses the ankle and divides into  two dorsal digital nerves—one for the medial  side of the big toe, and the other for the adjoining sides  of the second and third toes.   The lateral branch also divides into two dorsal digital  nerves for the adjoining sides of the third and fourth,  and fourth and fifth toes.   Communicating branches. The medial branch  communicates with the saphenous and deep peroneal  nerves and the lateral branch with the sural nerve.    Superficial peroneal nerve supplies both peronei and  then divides into medial and lateral cutaneous  branches for supplying dorsum of foot. Superficial  peroneal nerve can get entrapped as it penetrates the  deep fascia of leg. It may also be involved in lateral  compartment syndrome. Its paralysis causes loss of  eversion of foot at subtalar joint.   Identify the three tendons of a tripod formed by sartorius,  gracilis and semitendinosus to their insertion on the  upper medial surface of tibia.   Behind these tendons is present the tibial collateral  ligament of knee joint.   The great saphenous vein is visualised on the lower  one-third of tibia. Study these structures.   Medial side of the leg is formed by the medial surface  of the shaft of tibia. The greater part of this surface is  subcutaneous and is covered only by the skin and  superficial fascia. In the upper part, however, the  surface provides attachment to tibial collateral ligament  near the medial border, and provides insertion to  sartorius , gracilis and semitendinosus in front of the    ligament, all of which are covered by a thin layer of  deep fascia. The great saphenous vein and the saphenous  nerve lie in the superficial fascia as they cross the lower  one-third of this surface.   1 The skin, fasciae and periosteum on this surface are  supplied by saphenous nerve.   2 The tibial collateral ligament , morphologically,  represents degenerated part of the tendon of adductor  magnus. Partly it covers the insertion of  semimembranosus , and is itself crossed superficially  by the tendons of sartorius , gracilis , semitendinosus and  with anserine bursa around them.   3 Guy ropes: The three muscles inserted into the upper  part of the medial surface of tibia represent one  muscle from each of the three compartments of thigh,  corresponding to the three elements of the hip bone.  Sartorius belongs to anterior compartment of thigh,  and is supplied by the nerve of ilium or femoral  nerve.   Gracilis belongs to medial compartment of thigh,  and is supplied by the nerve of pubis or obturator  nerve.   Semitendinosus belongs to posterior compartment  of thigh, and is supplied by the nerve of ischium or  sciatic nerve.   These three muscles are anchored below at one  point, and spread out above to span the pelvis, like  three strings of a tent. From this arrangement it  appears that they act as "guy ropes", to stabilize the  bony pelvis on the femur (Fig. 8.13).   4 Anserine bursa: This is a large, complicated bursa,  with several diverticula. It separates the tendons of  sartorius, gracilis and semitendinosus at their  insertion from one another, from the bony surface  of tibia, and from the tibial collateral ligament  (Fig. 8.14).   5 The great saphenous vein ascends in front of the medial  malleolus, and crosses lower one-third of the medial  surface of tibia obliquely, with a backward  inclination. The saphenous nerve runs downwards  just in front of the great saphenous vein. The vein is  accompanied by lymphatics from the foot, which    FRONT, LATERAL AND MEDIAL SIDES OF LEG AND DORSUM OF FOOT    Bursa anserine between insertion of sartorius,  gracilis, semitendinosus and tibial collateral ligament  may get inflamed. It is called anserina bursitis.    Fig. 8.13: Sartorius, gracilis and semitendinosus form the guy  ropes for the tent of pelvis   Tall Himalayas are never dry places  Tibialis anterior  Extensor hallucis longus  Anterior tibial artery  Deep peroneal nerve  Extensor digitorum longus  Peroneus tertius    • Superior and inferior extensor retinacula and  superior and inferior peroneal retinacula retain the  tendons in place during movements of various  joints.   • Dorsum of foot contains a extensor digitorum  brevis, while dorsum of hand has no muscle of its  own.   • Long and short saphenous veins start on the  dorsum of foot. Long saphenous vein lying  anterior to medial malleolus is used for giving  intravenous fluids/blood in case of emergency.   • Medial surface of tibia is bare. It is crossed by long  saphenous vein and saphenous nerve in the lower  one-third of leg.   • Guy ropes, formed by sartorius, gracilis and  semitendinosus stablise the pelvis on the thigh and  leg   • Dorsalis pedis is palpated on the dorsum of foot  on medial cuneiform between extensor hallucis  longus and extensor digitorum longus.    New medical students were asked by their seniors  to run for 3 kilometers everyday. Few of them  developed severe pain above their ankles after 4 days  and could not continue.   Ans: When young persons do strenuous work, e.g.  running everyday for three kilometers, their extensor  tendons in front of the ankle joint got stretched and  tired, giving rise to pain above the ankle. In addition  there would be inflammation of the tendon sheaths  as well, aggravating the pain.   4. The structure passing under cover of superior  extensor retinaculum is:   6. Which of the following is not an action of tibialis  anterior?   8. Paralysis of muscles of anterior compartment of leg  leads to loss of:   The back or posterior compartment of the leg is also  called the calf, corresponds to the front of forearm. This  is the bulkiest of the three compartments of leg, because  of the powerful antigravity superficial muscles, e.g.  gastrocnemius, and soleus, and are quite large in size.  They raise the heel during walking. These muscles are  inserted into the heel. The deeper muscles cross the  ankle medially to enter the sole.   Corresponding to the two bones of the leg, there are  two arteries, the posterior tibial and peroneal, but there  is only one nerve, the tibial, which represents both the  median and ulnar nerves of the forearm.   The horizontal incision (vi) in the skin is already given  (see Fig. 5.2). Carry this incision along the lateral and  medial borders of the leg. Reflect whole skin of the back  of leg distally till the heel (ix).   Identify the structures, e.g. great and small saphenous  veins, medial and lateral calcanean arteries, and nerves  in the superficial fascia.   The superficial fascia of the back of the leg contains:  The small and great saphenous veins and their  tributaries, several cutaneous nerves, and the medial  and lateral calcanean arteries.   The vein is formed on the dorsum of the foot by the  union of the lateral end of the dorsal venous arch with  the lateral marginal vein (see Fig. 8.1). It enters the back  of the leg by passing behind the lateral malleolus. In    the leg, it ascends lateral to the tendocalcaneus, and  then along the middle line of the calf, to the lower part  of the popliteal fossa. Here it pierces the deep fascia  and opens into the popliteal vein. It drains the lateral  border of the foot, the heel, and the back of the leg. It is  connected with the great saphenous and with the deep  veins, and is accompanied by the sural nerve.   This vein begins on the dorsum of the foot by union of  the medial end of the dorsal venous arch with the  medial marginal vein (see Fig. 8.1). It ascends in front  of the medial malleolus. In the lower one-third of the  leg, it passes obliquely across the medial surface of the  tibia. In the upper two-thirds of the leg, the vein ascends  along the medial border of the tibia, to the postero¬  medial side of the knee. It is accompanied by the  saphenous nerve. In the thigh it inclines forwards to  reach saphenous opening and drains into femoral vein.   The skin of the calf can be divided into three vertical  areas, medial, central and lateral (Fig. 9.1). Roughly  there are two nerves for each area, with an additional  nerve for the heel. The medial area is supplied by the  saphenous nerve and by the posterior branch of the  medial cutaneous nerve of the thigh; the central area  by the posterior cutaneous nerve of the thigh and by  the sural nerve; the lateral area by the lateral cutaneous  nerve of the calf and the peroneal communicating nerve.  The lower part of the lateral area is supplied by the  sural nerve. The heel is supplied by the medial calcaneal  branches of the tibial nerve.   1 The saphenous nerve (L3, L4) is a branch of the  posterior division of the femoral nerve (see Fig. 8.2).  It arises in the femoral triangle. It pierces the deep  fascia on the medial side of the knee between the    Fig. 9.1 : Superficial veins and cutaneous nerves of the back of  the leg and the heel    sartorius and the gracilis, and descends close to the  great saphenous vein. It supplies the skin of most of  the medial area of the leg, and the medial border of  the foot up to the ball of the big toe. During  venesection this nerve should not be injured.   2 The posterior division of the medial cutaneous nerve of  the thigh (L2, L3) supplies the skin of the upper most  part of the medial area of the calf.   3 The posterior cutaneous nerve of the thigh (SI, S2, S3) is  a branch of the sacral plexus and descends along with  the small saphenous vein, to supply the skin of the  upper half of the central area of the calf.   4 The sural nerve (L5, SI, S2) is a branch of the tibial  nerve in the popliteal fossa. It descends between the  two heads of the gastrocnemius. It accompanies the  small saphenous vein. It is joined by the peroneal  communicating nerve about 5 cm above the heel.  After passing behind the lateral malleolus, the nerve  runs forwards along the lateral border of the foot,  and ends at the lateral side of the little toe. It supplies  the skin shown in (Fig. 9.1).   5 The lateral cutaneous nerve of the calf (L4, L5, SI) is a  branch of the common peroneal nerve in the popliteal  fossa. It supplies the skin of the upper two-thirds of  the lateral area of the leg (both in front and behind).   6 The peroneal or sural communicating nerve (L5, SI, S2)  is a branch of the common peroneal nerve. It  descends to join the sural nerve about 5 cm above  the heel. Before joining the latter it supplies the skin  of the lateral area of calf.    7 The medial calcanean branches (SI, S2) of the tibial  nerve perforate the flexor retinaculum and supply  the skin of the heel and the medial side of the sole of  the foot.   • Sural nerve can be grafted, as it is only sensory,  superficial and is easily identified lying between  tendon of tendocalcaneus and lateral malleolus.   Incise the deep fascia vertically and reflect it. Define the  flexor retinaculum posteroinferiorto the medial malleolus  and identify the tendons enclosed in synovial sheaths  passing deep to it.   Identify the medial and lateral bellies of gastrocnemius  muscle. Cut the medial belly 5 cm distal to the origin.  Reflect it laterally to locate the popliteal vessels and tibial  nerve. Identify plantaris muscle with its longest tendon  situated posteromedial to lateral head to gastrocnemius.   Reflect the lateral head of gastrocnemius 5 cm distal  to its origin. Both the bellies now can be turned distally.  Deep to gastrocnemius, expose the strong soleus  muscle.   The popliteal vessels and tibial nerve pass deep or  anterior to the fibrous arch between the upper parts of  the two leg bones.   The posterior compartment of leg is bounded and  subdivided by the deep fascia. It is thin above but thick  near the ankle, where it forms the flexor and superior  peroneal retinacula.   The boundaries of the posterior compartment of the  leg are as follows.   The posterior compartment is subdivided into three  parts—superficial, middle and deep, by two strong  fascial septa.   The superficial transverse fascial septum (Fig. 9.8)  separates the superficial and deep muscles of the back  of the leg, and encloses the posterior tibial vessels and  tibial nerve. It is attached:    a. Above , to the soleal line of the tibia and the back  of the fibula, below the origin of the soleus.   b. Below , it becomes continuous with the flexor and  superior peroneal retinacula.   c. Medially , it is attached to the medial border of the  tibia.   c. Medially , it is attached to the vertical ridge on the  posterior surface of the tibia.   1 Attachments: The flexor retinaculum is attached  anteriorly to the posterior border and tip of the medial  malleolus and posteriorly and laterally to the medial  tubercle of the calcaneum (Fig. 9.2).   Septa pass from the retinaculum to the underlying  bone and divide the space deep to the retinaculum  into four compartments.   2 Structures passing deep to the retinaculum: These are  from medial to lateral side.   c. The posterior tibial artery and its terminal  branches, along with the accompanying veins.   e. The tendon of the flexor hallucis longus. Each  tendon occupies a separate compartment which  is lined by a synovial sheath. The nerve and artery  share a common compartment.   These structures (a) to (e) lie in a tarsal tunnel If the  nerve gets pressed, it leads to tarsal tunnel syndrome.   3 The lower part of the deep surface of the flexor  retinaculum gives origin to the greater part of the  abductor hallucis muscle.   4 Near the calcaneum, the retinaculum is pierced by  the medial calcanean vessels and nerves.   Sensory loss: Distal and middle phalanges including  nail beds of all toes ( see Fig. 8.2). The sensory loss is  in the skin over sole of foot.   The muscles of the back of leg are classified into two  groups—superficial and deep. The superficial muscles    Fig. 9.2 : Flexor retinaculum of the ankle, and the structures passing deep to it   1 The large size of the gastrosoleus is a human  character, and is directly related to the adoption of  an erect posture, and to the bipedal gait of man.  Soleus is homologous with flexor digitorum  superficialis of the front of forearm.   2 From an evolutionary point of view the long plantar  ligament is the divorced tendon of the gastrocnemius;  and the flexor digitorum brevis is the divorced distal  part of the soleus.   3 A small sesamoid bone called the fabella is present  in the tendon of origin of the lateral head of the  gastrocnemius.   4 A bursa Brodie's bursa lies deep to the medial head  of the gastrocnemius. The bursa is also deep to the  semimembranosus and may communicate with the  cavity of the knee joint.   5 The muscles of the calf play an important role in  circulation. Contractions of these muscles help in the    venous return from the lower limb. The soleus is  particularly important in this respect.   There are large, valveless, venous sinuses in its  substance. When the muscle contracts the blood in  these sinuses is pumped out. When it relaxes, it sucks  the blood from the superficial veins through the  perforators. The soleus is, therefore, called the  peripheral heart (Fig. 9.8).   6 The tendocalcaneus is the thickest and strongest  tendon of the body. It is about 15 cm long. It begins  near the middle of the leg, but its anterior surface  receives fleshy fibres of the soleus almost up to its  lower end. It is narrow and thick in the middle, and  expanded at both end and is attached to posterior  surface of calcaneum (Fig. 9.3).   7 Tendocalcaneus is also known as tendo-Achilles.  According to a Greek legend, Achilles was an  irresistible and invincible warrior. His mother, the  sea Goddess, had dipped him in the underground  river, Styx. No weapon could harm the body which  had been covered by the waters of Styx. But the  warrior was ultimately killed in the war of Trojans,  by the arrows hitting his vulnerable heel which was   This is a large powerful  muscle. It has two heads,  medial and lateral. It lies  superficial to the soleus.   The two heads of the  gastrocnemius, and  the soleus, are together  referred to as the gastro- b.  soleus or the triceps  surae (see Figs 2.12 and 9.3)   • The posterosuperior depression on the medial  condyle of the femur, behind the adductor  tubercle   • The adjoining raised area on the popliteal  surface of the femur   • The lateral surface of the lateral condyle of the  femur   The tendon of this muscle fuses with  the tendon of the soleus to form the  tendocalcaneus ortendoachilles, which  is inserted into the middle one-third of  the posterior surface of the calcaneum   It is a sole-shaped  multipennate muscle,  which lies deep to  the gastrocnemius  (Fig. 9.3)   It is vestigeal in human  beings. It has a short  belly and a long tendon  (Fig. 9.3)   c. The tendinous soleal arch that stretches  between the tibia and the fibula    a. Lower part of the lateral supracondylar  line of the femur    The tendon is thin and long. It lies  between the gastrocnemius and the  soleus, crossing from lateral to me  dial side   It is inserted on the posterior surface  of the calcaneum, medial to the tendo¬  calcaneus. Plantar aponeurosis is the  estranged part of the plantaris   Tibial nerve (SI, S2) The gastrocnemius and soleus are strong plantar   flexors of the foot, at the ankle joint. The gastroc¬  nemius is also a flexor of the knee. Plantar    flexion, produced by the gastrocnemius and the  soleus, is very important in walking and running   The soleus is more powerful than the gastroc¬  nemius, but the latter is faster acting. In walking,  the soleus overcomes the inertia of the body  weight, like the bottom gear of a car. When  movement is under way, the quicker acting  gastrocnemius increases the speed like the top  gear of a car. Soleus is chiefly a postural muscle,  to steady the leg on the foot   The plantaris is a rudimentary muscle, and is  accessory to the gastrocnemius. Its functional  importance is of transplantation    the only unprotected part of his body. His mother  had held him by one heel, and the water over this  heel had not flowed.   Once the soleus has been studied, separate it from its  attachment on tibia and reflect it laterally. Look for a  number of deep veins which emerge from this muscle.   Identify popliteus, situated above the soleus muscle.  Deep to soleus is the first intermuscular septum. Incise  this septum vertically to reach the long flexors of the  toes, e.g. flexor hallucis longus laterally and flexor  digitorum longus medially. Trace these tendons till the  flexor retinaculum. Turn the flexor hallucis longus  laterally and expose the second intermuscular septum.   Divide this septum to reveal the deepest muscle of  the posterior compartment of leg, e.g. tibialis posterior.  Trace its tendon also till flexor retinaculum. Study these  deep muscles.   Clean the lowest part of popliteal vessels and trace  its two terminal branches, anterior tibial into anterior  compartment and posterior tibial into the posterior  compartment of leg. Identify posterior tibial vessels and  tibial nerve in fibrofatty tissue between the two long  flexors of the leg deep to the first intermuscular septum.   Peroneal vessels are identified in the connective  tissue of the second intermuscular septum. Study their  origin, course and branches from the following text.   The nerve to popliteus deserves special mention.  Being a branch of tibial nerve it descends over the  popliteus to reach its distal border. There it supplies  the muscle after winding around its distal border. It also  supplies a branch to tibialis posterior muscle, both  tibiofibular joints and interosseous membrane.    Table 9.3: Deep muscles of the posterior compartment of the leg   Upper two-thirds of medial part of posterior  surface of tibia below the soleal line    Lower three-fourths of the posterior surface  of the fibula (except the lowest 2.5 cm)  and interosseous membrane (see Fig. 2.34)   Upper two-thirds of lateral part of posterior  surface of tibia below the soleal line  (see Fig. 2.28). Posterior surface of fibula in  front of the medial crest and posterior  surface of interosseous membrane   Bases of distal phalanges of shaft of lateral  four toes. Muscle ends in a tendon which divides  into four slips, one for each of the lateral four  toes. Each slip is attached to the plantar surface  of the distal phalanx of the digit concerned   Tuberosity of navicular bone and other tarsal  bones except talus. Insertion is extended into  2nd, 3rd and 4th metatarsal bones at their  bases   supply and actions of deep muscles of the posterior compartment of the leg   Unlocks knee joint by lateral rotation of femur on tibia prior to flexion   Flexes distal phalanges, plantar flexor of ankle joint; supports medial and  lateral longitudinal arches of foot   Flexes distal phalanx of big toe; plantar flexor of ankle joint; supports medial  longitudinal arch of foot   Plantar flexor of ankle joint; inverts foot at subtalar joint, supports medial  longitudinal arch of foot (Fig. 9.4)   The deep muscles of the back of the leg are the  popliteus, the flexor digitorum longus, the flexor  hallucis longus, and the tibialis posterior. They are  described in Tables 9.3 and 9.4.   1 The tendon crosses the tibialis posterior in lower part  of the leg. It passes deep to the flexor retinaculum to  enter the sole of foot. Here it crosses the tendon of  flexor hallucis longus (Fig. 9.4).   2 The tendon receives the insertion of the flexor  digitorum accessorius.   3 The slips for the digits give origin to the four  lumbrical muscles.   The tendon runs across the lower part of the posterior  surface of the tibia. Reaching the calcaneus it turns  forwards below the sustentaculum tali which serves as  a pulley for it. As the tendon lies on the medial side of  calcaneum, it runs deep to the flexor retinaculum and    is surrounded by a synovial sheath. The tendon then  runs forwards in the sole when it is crossed by the  tendon of flexor digitorum longus.   The tendon passes behind the medial malleolus,  grooving it. The tendon then passes deep to the flexor  retinaculum. The terminal part of the tendon supports  the spring ligament.    • The deep muscles are tested by palpating the calf  while the foot is being plantarflexed (Fig. 9.5).   • Tendo-Achilles reflex or ankle jerk (SI, S2): The foot  gets plantar flexed on tapping the tendocalcaneus  (Fig. 9.6).   • For thromboangiitis obliterans or occlusive disease  of lower limb arteries, sympathetic fibres to the  arteries are removed, so as to denervate the  arteries. Lumbar 2 and 3 ganglia with intervening  sympathetic trunk is removed, as these supply the  arteries of lower limb.    • In long distance air travel, sitting immobile can  lead to thrombosis of soleal venous sinuses. The  thrombus may get dislodged to block any other  artery. One must stretch the legs frequently.   • Dislocation or subluxation of ankle is common  during plantarflexion. Lower end of the leg bones,  i.e. medial malleolus, tibia, thin fibula and lateral  malleolus form tibiofibular mortice. This is wider  anteriorly and narrow posteriorly.   The trochlear surface of talus forming ankle joint  is also wider anteriorly and narrow posteriorly.  During dorsiflexion, wider trochlear surface fits  into narrow posterior part of the mortice. The joint  is stable and close packed.   During plantarflexion the narrow posterior  trochlear surface lies loosely in wider anterior part  of the mortice. The joint is unstable and can easily  get subluxated or dislocated. This occurs while  walking in high heels (Fig. 9.10).   It begins at the lower border of the popliteus, between  the tibia and the fibula, deep to the gastrocnemius  (Fig. 9.7).   It enters the back of leg by passing deep to the  tendinous arch of the soleus.   In the leg, it runs downwards and slightly medially,  to reach the posteromedial side of the ankle, midway  between the medial malleolus and the medial tubercle  of the calcaneum.   It terminates deep to flexor retinaculum (and the  origin of the abductor hallucis) by dividing, into the  lateral and medial plantar arteries (Fig. 9.2).   1 In the upper two-thirds of the leg, it lies deep to the  gastrocnemius, the soleus and the superficial  transverse fascial septum (Fig. 9.8).   2 In the lower one-third of the leg, it runs parallel to,  and 2.5 cm in front of, the medial border of the  tendocalcaneus. It is covered by skin and fasciae.   3 At the ankle, it lies deep to the flexor retinaculum  and the abductor hallucis (Fig. 9.2).   1 In the upper two-thirds of the leg, it lies on the tibialis  posterior (Fig. 9.8).   2 In the lower one-third of the leg, it lies on the flexor  digitorum longus and on the tibia.   3 At the ankle, it lies directly on the capsule of the ankle  joint between the flexor digitorum longus and the  flexor hallucis longus (Fig. 9.2).   Fig. 9.5: Testing the deep muscles of the calf by plantar  flexing the foot    Fig. 9.7 : Course of the posterior tibial and peroneal arteries and  the tibial nerve    The artery is accompanied by two venae comitantes  and by the tibial nerve.   1 The peroneal artery (Fig. 9.7) is the largest branch of  the posterior tibial artery. It is described later.   2 Several muscular branches are given off to muscles of  the back of the leg.   4 The anastomotic branches of the posterior tibial artery  are as follows.   a. The circumflex fibular branch winds round the  lateral side of the neck of the fibula to reach the  front of the knee where it takes part in the  anastomoses around the knee joint.   b. A communicating branch forms an arch with a  similar branch from the peroneal artery about 5 cm  above the ankle.   c. A malleolar branch anastomoses with other  arteries over the medial malleolus.   5 Terminal branches: These are the medial and lateral  plantar arteries. They will be studied in the sole  (Fig. 9.7).   This is the largest branch of the posterior tibial artery. It  supplies the posterior and lateral compartments of the  leg (Fig. 9.7).   It begins 2.5 cm below the lower border of the  popliteus.   It runs obliquely' towards the fibula, and descends  along the medial crest of the fibula, accompanied by  the nerve to the flexor hallucis longus. It passes behind  the inferior tibiofibular and ankle joints, medial to  peroneal tendons. It terminates by dividing into a  number of lateral calcanean branches (Fig. 9.7).   a. The large perforating branch pierces the  interosseous membrane 5 cm above the ankle, and  joins the lateral malleolar network.   b. The communicating branch anastomoses with a  similar branch from the posterior tibial artery,  about 5 cm above the lower end of the tibia.   The perforating branch of the peroneal artery may  reinforce, or even replace the dorsalis pedis artery.   The course and relations of the tibial nerve in the leg are  similar to those of the posterior tibial artery. Like the  artery, the tibial nerve also terminates by dividing into  the medial plantar and lateral plantar nerves (Fig. 9.2).   Long saphenous vein and saphenous nerve  Flexor digitorum longus  Soleus with venous sinuses    Fig. 9.8 : Transverse section through the middle of the leg, showing the arrangement of structures in the posterior compartment   To the tibialis posterior, the flexor digitorum longus;  the flexor hallucis longus, and the deep part of the  soleus (Figs 9.7 and 9.8).   Medial calcanean branches pierce the flexor  retinaculum, and supply the skin on the back and lower  surface of the heel.    * The posterior tibial pulse is palpated in doubtful  cases of intermittent claudication where a person  gets cramps and severe pain in calf muscles due  to lack of blood supply.   * The posterior tibial pulse can be felt against the  calcaneum about 2 cm below and behind the  medial malleolus (Fig. 9.9).   * The long tendon of plantaris is used for tendon  transplantation in the body.   * Tendocalcaneus can rupture in tennis players 5 cm  above its insertion. Plantar flexion is not possible.  The two ends must be stitched.   * High heels for long periods causes change in  posture. Knees are excessively bent, with lumbar  vertebrae pushed forwards. There is a lot of stress  on the muscles of back and those of the calf. So  many fashionable ladies wear high heels for short  time and change to flat ones soon (Fig. 9.10).    • Soleus acts as the peripheral heart, as it pushes the  venous blood upwards.   • Soleus acts like first gear while gastrocnemius act  like second and third gears during walking.   • All the muscles of back of leg/calf are supplied by  the tibial nerve   • Posterior tibial artery is palpated between medial  malleolus and calcaneus under the flexor  retinaculum.   • Posterior tibial artery ends by dividing into medial  and lateral plantar arteries.    An elderly man complained of pain on the inner  aspect of right ankle joint. The pain was also felt in  the area of sole.   Am: The syndrome is called tarsal tunnel syndrome if  tibial nerve gets entrapped under the flexor  retinaculum of the ankle. Since the tibial nerve gets  constricted, there is pain in the sole as the medial  and lateral plantar nerves are affected. There may  be paralysis of intrinsic muscles of the sole due to  compression of medial and lateral plantar nerves.   4. What relation of flexor digitorum longus is wrong  (not correct)?   a. The tendon crosses the tibialis posterior in lower  part of leg    c. The 4 slips of the tendon give origin to 3  lumbrical muscles   5. If tibial nerve is injured under flexor retinaculum,  the condition is called:   a. Base of distal phalanges of shaft of lateral 4 toes   7. Deep muscles of posterior compartment of leg are  supplied by:   1. a 2. a 3. c 4* c 5. a 6. d 7. a   The structure of the sole is similar to that of the palm.  The skin, superficial fascia, deep fascia, muscles, vessels  and nerves, are all comparable in these two homologous  parts. However, unlike the hand, the foot is an organ  of support and locomotion. Accordingly, the structures  of the foot get modified. The great toe has lost its  mobility and its power of prehension; the lesser four  toes are markedly reduced in size; and the tarsal bones  and the first metatarsal are enlarged to form a broad  base for better support. The arches of the foot serve as  elastic springs for efficient walking, running, jumping  and supporting the body weight.   Skin of the sole usually becomes very hard. To remove  it, the incision is given from heel through the root to the  tip of the middle toe. Reflect the skin and fatty superficial  fascia to each side of the sole. Look for cutaneous nerves  and vessels.   The skin of the sole, like that of the palm, is:   3 Creased. These features increase the efficiency of the  grip of the sole on the ground.   The skin is mainly supplied by three cutaneous  nerves (Fig. 10.1). The nerves are:   a. Medial calcanean branches of the tibial nerve, to  the posterior and medial portions;   b. Branches from the medial plantar nerve to the  larger, anteromedial portion including the medial  three and a half digits; and    c. Branches from the lateral plantar nerve to the  smaller anterolateral portion including the lateral  one and a half digits.   d. Small areas on medial and lateral sides are  innervated by saphenous and sural nerves.   These nerves are derived from spinal nerves L4, L5  and SI. The segmental distribution is shown in Fig. 10.2.  In eliciting the plantar reflex, the area supplied by  segment SI is stimulated.   The deep fascia on the plantar aspect of toes is thickened  to form fibrous flexor sheaths; proximally it is continuous  with the plantar aponeurosis.   Identify the cutaneous branches from medial and  lateral plantar arteries and nerves on the respective  sides of plantar aponeurosis.    Between the five distal slips of the aponeurosis trace  the digital nerves and vessels from medial plantar nerve  and vessels for three and a half medial toes and from  lateral plantar nerve and vessels for lateral one and a  half toes.   Divide the plantar aponeurosis 4 cm distal to the heel.  Reflect the cut ends both proximally and distally. This  exposes the three muscles of the first layer of sole.   Medial plantar nerve and vessels are easily visualised  close to the medial border of sole. Stems of lateral plantar  nerve and vessels including its superficial division are  also seen.   The superficial fascia of the sole is fibrous and dense.  Fibrous bands bind the skin to the deep fascia or plantar  aponeurosis, and divide the subcutaneous fat into small  tight compartments which serve as water-cushions and  reinforce the spring-effect of the arches of the foot  during walking, running and jumping. The fascia is very  thick and dense over the weight-bearing points. It  contains cutaneous nerves and vessels. Thickened  bands of superficial fascia stretch across the roots of the  toes forming the superficial transverse metatarsal ligaments.    Plantar aponeurosis represents the distal part of the  plantaris which has become separated from the rest of  the muscle during evolution because of the enlargement  of the heel.   The aponeurosis is triangular in shape. The apex is  proximal. It is attached to the medial tubercle of the  calcaneum, proximal to the attachment of the flexor  digitorum brevis. The base is distal. It divides into five  processes near the heads of the metatarsal bones. The  digital nerves and vessels pass through the intervals  between the processes.   Each process splits, opposite the metatarso¬  phalangeal joints, into a superficial and a deep slip. The  superficial slip is attached to dermis of skin. The deep  slip divides into two parts which embrace the flexor  tendons, and blend with the fibrous flexor sheaths and  with the deep transverse metatarsal ligaments.   From the margins of the aponeurosis, lateral and  medial vertical intermuscular septa pass deeply, and  divide the sole into three compartments. Thinner  transverse septa arise from the vertical septa and divide  the muscles of the sole into four layers.   3 It helps in maintaining the longitudinal arches of the  foot.   4 It gives origin to muscles of the first layer of the sole.    The deep fascia covering the sole is thick in the centre  and thin at the sides. The thickened central part is  known as the plantar aponeurosis (Fig. 10.3).    The plantar aponeurosis differs from the palmar  aponeurosis in giving off an additional process to the  great toe, which restricts the movements of the latter.   These are four short, flat bands which connect the  plantar ligaments of the adjoining metatarso¬  phalangeal joints. They are related dorsally to the  interossei, and ventrally to the lumbricals and the  digital vessels and nerves.   These are made up of the deep fascia of the toes. Their  structure is similar to that of the fibrous flexor sheaths  of the fingers. They retain the flexor tendons in position  during flexion of the toes (Fig. 10.3).    Plantar fasciitis occurs in policemen due to stretching  of the plantar aponeurosis. This results in pain in  the heel region, especially during standing.    The muscles of the sole are arranged in four layers,  which will be considered one by one.   Cut through the flexor digitorum brevis near its middle  taking care to preserve the underlying lateral plantar  nerve and vessels. Reflect the distal part distally till the  toes.   Detach the abductor digiti minimi and identify the  lateral head of the flexor digitorum accessorius till its  insertion into the tendon of flexor digitorum longus.   Trace the long flexor tendons through the fibrous  flexor sheath into the base of distal phalanges of toes.   Follow the lumbricals to their insertion into the base  of the proximal phalanx and into the extensor expansion  of the dorsum of toes. Study the muscles of second  layer comprising the long flexor tendons and associated  muscles.   Cut through both the long flexor tendons (flexor  hallucis longus and flexor digitorum longus) and flexor  digitorum accessorius where all the three are united to  each other. Reflect the ends proximally and distally to  reveal the muscles of third layer of sole.    These muscles are described in Tables 10.1 and 10.2 and  shown in Figs 10.4a and b.   The contents of second layer are the tendons of the  flexor digitorum longus, and of the flexor hallucis  longus; and the flexor digitorum accessorius and  lumbrical muscles. The muscles are described in Tables  10.3 and 10.4.   Separate flexor hallucis brevis and oblique head of  adductor hallucis from their origin and reflect them  distally.   Preserve the plantar arch and deep plantar nerve.  Look for sesamoid bones at the insertion of flexor  hallucis brevis.   Reflect the transverse head of adductor hallucis  medially. On cutting the deep transverse metatarsal  ligament on both sides of second toe, tendons of  interossei muscles are recognised.   Detach the flexor digiti minimi brevis from its origin  and reflect it forwards. This will show the laterally  situated interossei muscles.   Identify and examine the attachment of tendon of  tibialis posterior on the medial side of foot.   Trace the course of tendon of peroneus longus  through the groove in the cuboid bone across the sole  to its insertions into lateral sides of base of first  metatarsal and medial cuneiform bone.   After studying the muscles of the third layer, detach  them from their origins towards their insertions. The  muscles of the fourth layer are visualised.   The third layer of the sole contains three muscles. These  are the flexor hallucis brevis , the flexor digiti minimi brevis,  and the adductor hallucis (Figs 10.6a and b). They are  described in Tables 10.5 and 10.6.   The structures present in the fourth layer of the sole  are the interosseous muscles, and the tendons of the tibialis  posterior and of the peroneus longus.   These are small muscles placed between the metatarsal  bones. There are three plantar and four dorsal interossei  (Figs 10.7 and 10.8).    The muscles of the first layer are the flexor digitorum  brevis, the abductor hallucis, and the abductor digiti minimi.   This muscle lies along the  medial border of foot, and  covers the origin of the  plantar vessels and nerves   This muscle lies along  the lateral border of foot  (Fig. 10.4a)    The muscle ends in four tendons for the lateral four  toes. Opposite the base of the proximal phalanx each  tendon divides into two slips that are inserted into the  margins of the middle phalanx. The tendon of the flexor  digitorum longus (for that digit) passes through the gap  between the two slips. Note that the insertion is similar to  that of the flexor digitorum superficialis of the hand   The tendon fuses with the medial portion of the tendon  of the flexor hallucis brevis. It is inserted into the medial  side of the base of the proximal phalanx of the great toe    The tendon fuses with the tendon of the flexor digiti minimi  brevis. It is inserted into the lateral side of the base of the  proximal phalanx of the little toe    .2: Nerve supply and actions of muscles of the first layer of the sole   Flexion of the toes at the proximal interphalangeal joints  and metatarsophalangeal joints   Abduction of the great toe away from the second toe  Abduction of the little toe   Dissect the medial plantar nerve and vessels on the  medial side of sole. Lateral plantar nerve and vessels  also enter the sole from the medial side. These cross  the sole to reach the lateral side. Here lateral plantar  artery forms a plantar arch across the sole which gives  numerous branches. The lateral plantar nerve divides  into a superficial and deep branch. The latter runs in  the concavity of the plantar arch. The course branches  of nerves and vessels are given in the text.   1 The chief arteries of the sole are the medial and lateral  plantar arteries. They are terminal branches of the  posterior tibial artery (Fig. 10.9).   2 The chief nerves of the sole are the medial and lateral  plantar nerves. They are terminal branches of the  tibial nerve.   3 These arteries and nerves begin deep to the flexor  retinaculum. The posterior tibial artery divides into  the medial and lateral plantar arteries a little higher  than the division of tibial nerve. As a result the  arteries are closer to the margins of the sole than the  corresponding nerves.    4 The medial plantar vessels and nerve lie between the  abductor hallucis and the flexor digitorum brevis  (Fig. 10.4b).   5 The lateral plantar vessels and nerve run obliquely  towards the base of the 5th metatarsal bone, between  the first and second layers of the sole. Here the artery  turns medially and becomes continuous with the  plantar arch. This arch lies between the third and  fourth layers of the sole (Fig. 10.9). The plantar arch  is accompanied by the deep branch of the lateral  plantar nerve.   Medial plantar nerve is the larger terminal branch of  the tibial nerve. It passes forwards between abductor  hallucis and flexor digitorum brevis and divides into its  branches. In its distribution, it resembles the median  nerve of the hand (Fig. 10.4b).   3 The flexor hallucis brevis receives a branch from the  first digital nerve.    Table 10.3: Muscles and tendons of the second layer of the sole (Fig. 10.5)  Origin from Insertion    From upper two-thirds of the medial part  of the posterior surface of tibia below  the soleal line    The muscle divides into four tendons. Each  is inserted to the plantar surface of distal  phalanx of second to fifth digit   It is so called because it is  accessory to the flexor  digitorum longus   There are four of them,  numbered from medial to  lateral side (Fig. 10.5)   a. Medial head is large and fleshy;  it arises from the medial concave  surface of the calcaneum   b. Lateral head is smaller and  tendinous; it arises from the  calcaneum in front of the lateral  tubercle,   They arise from the tendons of the  flexor digitorum longus. The first  lumbrical is unipennate, and the  others are bipennate  First lumbrical arises from medial side  of 1st tendon of flexor digitorum longus  Second lumbrical arises from adjacent  sides of 1st and 2nd tendons of flexor  digitorum longus   Third lumbrical arises from adjacent  sides of 2nd and 3rd tendons of flexor  digitorum longus   Fourth lumbrical arises from adjacent  sides of 3rd and 4th tendons of flexor  digitorum longus   Lower three-fourths of the posterior  surface of fibula except lowest 2.5 cm  and adjoining interosseous membrane    The muscle fibres are inserted into the  lateral side of the tendon of the flexor  digitorum longus    Their tendons pass forwards on the medial  sides of the metatarsophalangeal joints of  the lateral four toes, and then dorsally for  insertion into the extensor expansion    Plantar surface of the base of the distal  phalanx of the great toe    Table 10.4: Nerve supply and actions of muscles and tendons of the second layer of the sole   Plantar flexion of lateral four toes  Plantar flexion of ankle  Maintains medial longitudinal arch   plantar nerve; and the other three  by the deep branch of lateral  plantar nerve    4 The first lumbrical muscle receives a branch from  the second digital nerve.   Cutaneous branches supply the skin of the medial part  of the sole, and of the medial three and a half toes  through four digital branches.   The first digital nerve supplies the medial side of  the great toe.    They maintain extension of the digits at the inter-  phalangeal joints so that in walking and running  the toes do not buckle under   Plantar flexor of the big toe, plantar flexor of ankle  joint, maintains medial longitudinal arch   The second nerve supplies the adjacent sides of the  first and second toes.   The third nerve supplies the adjacent sides of the  second and third toes;   The fourth nerve supplies the adjacent sides of the  third and fourth toes.    Fig. 10.5 : Muscles and tendons of the second layer of the sole    Fig. 10.4b: Scheme to show the distribution of the medial plantar Fig. 10.6a: Muscles of third layer of the sole. The tendons of  nerve with Morton’s neuroma on one branch of the nerve tibialis posterior and peroneus longus belong to the fourth layer    Fig. 10.6b: Scheme to show the distribution of the lateral plantar  nerve    Each digital nerve gives off a dorsal branch which  supplies structures around the nail of the digit concerned.   Lateral plantar nerve (Fig. 10.6b) is the smaller terminal  branch of the tibial nerve. It passes laterally and  forwards till base of fifth metatarsal, where it divides  into superficial and deep branches. In its distribution,  it resembles the ulnar nerve in the hand.   The main trunk supplies two muscles, the flexor  digitorum accessorius and the abductor digiti minimi , and  the skin of the sole. The main trunk ends by dividing  into superficial and deep branches.   The superficial branch divides into two branches,  lateral and medial. The lateral branch supplies three  muscles— -flexor digiti minimi brevis , the third plantar and  fourth dorsal interossei, and the skin on the lateral side  of the little toe. The medial branch communicates with  the medial plantar nerve, and supplies the skin lining  the fourth interdigital cleft.   The deep branch supplies nine muscles, including the  second, third and fourth lumbricals; first, second and  third dorsal interossei; first and second plantar  interossei and adductor hallucis.    * A neuroma may be formed on the branch of  medial plantar nerve between 3rd and 4th  metatarsal bones. It is called Morton's neuroma  (Fig. 10.4b). This causes pain between third and  fourth metatarsals. It may be also due to pressure  on digital nerve between 3rd and 4th metatarsals.   * Any of the digital nerves, especially the one in the  third interdigital cleft may develop neuroma. This  is a painful condition.   Medial plantar artery is a smaller terminal branch of  the posterior tibial artery. It lies along the medial border  of foot and divides into branches.   It gives off cutaneous, muscular branches to the  overlying skin and to the adjoining muscles, and three  small superficial digital branches that end by joining  the first, second and third plantar metatarsal arteries  which are branches of the plantar arch (Fig. 10.9).   It covers the plantar  surface of the first  metatarsal bone  (Fig. 10.6b)   a. The lateral limb , from the medial part of the  plantar surface of the cuboid bone, behind  the groove for the peroneus longus and  from the adjacent side of the lateral  cuneiform bone   b. The medial limb is a direct continuation of  the tendon of tibialis posterior into the foot    The muscle splits into medial and lateral parts,  each of which ends in a tendon. Each tendon is  inserted into the corresponding side of the base  of the proximal phalanx of the great toe   a. The oblique head is large, and arises from  the bases of the second, third, and fourth  metatarsals, from the sheath of the tendon  of the peroneus longus   b. The transverse head is small, and arises  from the deep metatarsal ligament, and the  plantar ligaments of the metatarsophalan¬  geal joints of the third, fourth and fifth toes  (transverse head has no bony origin)    On the lateral side of the base of the proximal  phalanx of the big toe, in common with the  lateral tendon of the flexor hallucis brevis    Into the lateral side of the base of the proximal  phalanx of the little toe    Table 1 0S: Nerve supply and actions of muscles of the third layer of the sole    Deep branch of lateral plantar  nerve, which terminates in  this muscle   Flexes the proximal phalanx at the metatarsophalangeal  joint of the great toe    Flexes the proximal phalanx at the metatarsophalangeal  joint of the little toe   (three bellies), unipennate, slender  muscle bellies. Tendons pass on  medial sides of third, fourth and fifth  toes (Fig. 10.7)   Bases and medial sides of third, Medial sides of bases of proximal phalanges and  fourth and fifth metatarsals dorsal digital expansions of 3rd, 4th and 5th toes    Adjacent sides of metatarsal Bases of proximal phalanges and dorsal digital  bones expansion of toes; first on medial side of 2nd toe;   second on lateral side of 2nd toe; third on lateral  side of 3rd toe and fourth on lateral side of 4th toe    Posterior surfaces of leg bones Tuberosity of navicular ( see Table 9.3)   Upper part of lateral surface of Base of 1st metatarsal ( see Table 8.3)  fibula    Table 10.8: Nerve supply and actions of muscles of the fourth layer of the sole   First and second by lateral plantar  (deep branch). Third by lateral plantar  (superficial branch)   Adductors of third, fourth and fifth toes toward the axis.  Flexor of metatarsophalangeal and extensor of inter-  phalangeal joints of third, fourth and fifth toes    First, second, third by lateral plantar Abductors of toes from axis of second toe. First and  (deep branch), fourth dorsal second cause medial and lateral abduction of second   interosseous by superficial branch toe. Third and fourth for abduction of 3rd and 4th toes  of lateral plantar   Lateral plantar artery is the larger terminal branch of  the posterior tibial artery. At the base of the fifth  metatarsal bone it gives a superficial branch and then  continues as the plantar arch (Figs 10.9 and 10.10).   Cutaneous branches supply the skin and fasciae of the  lateral part of the sole.   Anastomotic branches reach the lateral border of the foot  and anastomose with arteries on the dorsum of the foot.   A calcanean branch is occasionally given off to the skin  of the heel.   Plantar arch is formed by the direct continuation of the  lateral plantar artery after it has given off the superficial    Fig. 10.10: Transverse section of the foot through the metatarsals showing the arrangement of structures in the sole    branch and is completed medially by the dorsalis pedis  artery. It extends from the base of the fifth metatarsal  bone to the proximal part of the first intermetatarsal  space, and lies between the third and fourth layers of  the sole. It is accompanied by venae comitantes. The  deep branch of the lateral plantar nerve lies in the  concavity of the plantar arch (Fig. 10.9 and 10.10).   1 Four plantar metatarsal arteries run distally, one in  each intermetatarsal space. Each artery ends by  dividing into two plantar digital branches for adjacent  sides of two digits. The first artery also gives off a  branch to the medial side of the great toe. The lateral  side of the little toe gets a direct branch from the  lateral plantar artery.   2 The plantar arch gives off three proximal perforating  arteries that pass through the second, third and fourth  intermetatarsal spaces and communicate with the  dorsal metatarsal arteries which are the branches of  the arcuate artery.   The distal end of each plantar metatarsal artery  gives off a distal perforating artery which joins the distal  part of the corresponding dorsal metatarsal artery  (Fig. 10.9).    • Fracture of shaft of 2nd/3rd/4th/metatarsal  bones is called "march fracture". It is seen in army  personnel, policemen as they have to march a lot.  It occurs due to decalcification and vascular  necrosis.   • Normal architecture of foot is subjected to insults  due to "high heels". Females apparently look  taller, smarter but may suffer from sprains and  dislocations of the ankle joint ( see Fig. 9.14).   • If foot is dorsiflexed, person walks on the heel  condition is called "Talipes calcaneus" (Fig. 10.11).   • If foot is plantar flexed, person walks on toes. The  condition is called "Talipes equinus" (Fig. 10.12).   • If medial border of foot is raised, person walks on  lateral border of foot. The condition is "Talipes  varus" (Fig. 10.13).   • If lateral border of foot is raised, person walks on  medial border of foot. The condition is called  "Talipes valgus" (Fig. 10.14).    Fig. 10.15: Schematic transverse section through the metatarsal  bones (1-5) to show the origins of the interossei   • Extrinsic muscles are supplied by the nerve of the  respective compartments of the leg.   • The muscles of the sole maintain the arches of the  foot.    * Between 1st and 2nd layers of muscles are the  trunks of medial plantar and lateral plantar nerves  and vessels.   * Between the 3rd and 4th layers are the plantar arch  and deep branch of lateral plantar nerve.    A young female complains of severe pain along the  middle of her right sole.   Ans: This may due to a "neuroma" in the common  digital nerve between third and fourth metatarsal  bones. This is a benign proliferation of the nerve  fibres.   a. Muscular branches to abductor hallucis, flexor  digitorum brevis, both of 1st layer of sole; first  lumbrical of 2nd layer of sole and flexor hallucis  brevis of 3rd layer of sole   c. It also gives articular branches to the joints in  its territory of distribution.   3. In the movement of eversion of foot, all of the  following muscles are involved except:   6. All of following structures pass behind medial  malleolus beneath flexor retinaculum of ankle  region except:   1. d 2.c 3. c 4. b 5. d 6. c 7.b 8.b   Venous and Lymphatic  Drainage, Segmental  Innervation, and Comparison  of Lower and Upper Limbs   Venous drainage acquires importance as blood has to  flow up against the gravity.   The saphenous veins can be "easily seen" in the leg.  The varicose veins, if occur, look quite ugly under the  skin. Effort should be made not to develop the varicose  veins. The lymph travels mostly to the inguinal group  of lymph nodes.   The sensory nerves are derived only from ventral  rami of LI to L5 and SI to S3 segments of spinal cord.   Lower limb bud rotates medially, so that extensor  compartment lies on front, while flexor compartment  is present on the back of thigh. Tibia and big toe lie  along the pre-axial border while fibula and little toe  are along the post-axial border of the limb.   Consideration of the venous drainage is of great  importance because in the lower limb venous blood has  to ascend against gravity. This is aided by a number of  local factors, the failure of which gives rise to varicose  veins.   1 Negative intrathoracic pressure, which is made more  negative during inspiration;   4 The presence of valves, which support and divide  the long column of blood into shorter columns. These  also maintain a unidirectional flow.   1 Venous: The veins of the lower limb are more  muscular than the veins of any other part of the body.  They have greater number of valves. Superficial veins  are connected to deep veins by perforators.   2 Muscular: When the limb is active, muscular  contraction compresses the deep veins and drives  the blood in them upwards.   3 Fascial: The tight sleeve of deep fascia makes  muscular compression of the veins much more  effective by limiting outward bulging of the muscles.   The veins may be classified into three groups:  superficial, deep and perforating.   They include the great and small saphenous veins, and  their tributaries. They lie in the superficial fascia, on  the surface of deep fascia (see Figs 3.4 and 8.1). They  are thick-walled because of the presence of smooth  muscle and some fibrous and elastic tissues in their  walls. Valves are more numerous in the distal parts of  these veins than in their proximal parts. A large  proportion of their blood is drained into the deep veins  through the perforating veins.   These are the medial plantar, lateral plantar, dorsalis  pedis, anterior and posterior tibial, peroneal, popliteal,  and femoral veins, and their tributaries. They  accompany the arteries, and are supported by powerful  surrdunding muscles. The valves are more numerous in    VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS    deep veins than in superficial veins. They are more  efficient channels than the superficial veins because of  the driving force of muscular contraction.   They connect the superficial with the deep veins. Their  valves permit only one way flow of blood, from the  superficial to the deep veins. There are about five  perforators along the great saphenous vein, and one  perforator along the small saphenous vein.   1 The dorsal venous arch lies on the dorsum of the  foot over the proximal parts of the metatarsal bones.  It receives four dorsal metatarsal veins each of which  is formed by the union of two dorsal digital veins  {see Fig. 8.1).   2 The great or long saphenous vein is formed by the  union of the medial end of dorsal venous arch with  the medial marginal vein which drains the medial  side of great toe. It passes upwards in front of the  medial malleolus, crosses the lower one-third of the  medial surface of tibia obliquely, and runs along its  medial border to reach the back of the knee. The  saphenous nerve runs in front of the great saphenous  vein.   3 In the thigh, it inclines forwards to reach the saphenous  opening where it pierces the cribriform fascia and  opens into the femoral vein. Before piercing the  cribriform fascia, it receives three named tributaries  corresponding to the three cutaneous arteries, and  also many unnamed tributaries (Fig. 11.1).   It contains about 10 to 15 valves which prevent back  flow of the venous blood, which tends to occur because  of gravity. One valve is always present at the  saphenofemoral junction. Incompetence of these valves  makes the vein dilated and tortuous leading to varicose  veins.   The vein is also connected to the deep veins of the  limb by perforating veins. There are three medial  perforators just above the ankle, one perforator just  below the knee, and another one in the region of the  adductor canal (Fig. 11.2). The perforating veins are also  provided with valves which permit flow of blood only  from the superficial to the deep veins. Failure of the  valves also gives rise to varicose veins.   In the leg: It communicates freely with the small  saphenous vein and with deep veins.    Popliteal vein formed  by venae comitantes  of posterior and  anterior tibial arteries    Fig. 11.1: Scheme to show the arrangement of the veins of lower  limb. Popliteal, short saphenous and venae comitantes of  posterior tibial artery are on posterior aspect    Fig- 11 2.: Tributaries and perforating veins of the great saphenous  vein   1 The anterior vein of the leg runs upwards, forwards  and medially, from the lateral side of the ankle.   2 The posterior arch vein is large and constant. It  begins from a series of small venous arches which  connect the medial ankle perforators, and runs  upwards to join the great saphenous vein just below  the knee.   3 A vein from the calf: This vein also communicates  with the small saphenous vein.   1 The accessory saphenous vein drains the  posteromedial side of the thigh.   2 The anterior cutaneous vein of the thigh drains the  lower part of the front of the thigh.   Just before termination: Deep external pudendal vein.  The thoracoepigastric vein runs along the anterolateral  wall of the trunk. It connects the superficial epigastric  vein with the lateral thoracic vein. Thus it is an  important connection between the veins of the upper  and lower limbs.   The vein is formed on the dorsum of the foot by the  union of the lateral end of the dorsal venous arch with  the lateral marginal vein (see Fig. 9.1). It enters the back  of the leg by passing behind the lateral malleolus. In  the leg, it ascends lateral to the tendocalcaneus, and  then along the middle line of the calf, to the lower part  of the popliteal fossa. Here it pierces the deep fascia  and opens into the popliteal vein. It drains the lateral  border of the foot, the heel, and the back of the leg. It is  connected with the great saphenous and with the deep  veins, and is accompanied by the sural nerve.   As already mentioned, they connect the superficial with  the deep veins (Fig. 11.2). These are classified as follows.   Indirect perforating veins connect the superficial veins  with the deep veins through the muscular veins  (Fig. 11.3).   Direct perforating veins (Fig. 11.4) connect the  superficial veins directly with the deep veins. The great  and small saphenous veins are the large direct  perforators. The small direct perforating veins  (Fig. 11.5) are follows:    1 In the thigh: The adductor canal perforator connects the  great saphenous vein with the femoral vein in the  lower part of the adductor canal.    Adductor canal perforator  Popliteal vein  Short saphenous vein  Below knee perforator   Lateral perforator  Upper medial perforator  Middle medial perforator  Lower medial perforator   VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS   One perforator connects the great saphenous vein  or the posterior arch vein with the posterior tibial  vein.   A lateral perforator is present at the junction of the  middle and lower thirds of the leg. It connects the  small saphenous vein, or one of its tributaries with  the peroneal vein.   Medially there are three perforators which connect  the posterior arch vein with the posterior tibial vein.   • The upper medial perforator lies at the junction of  the middle and lower thirds of the leg.   • The lower medial perforator lies posteroinferior to  the medial malleolus.    • Calf pump and peripheral heart. In the upright  position of the body, the venous return from the  lower limb depends largely on the contraction  of calf muscles. These muscles are, therefore,  known as the "calf pump".   For the same reason the soleus is called the  peripheral heart (see Fig. 9.3). When this muscle  contracts, blood contained in large sinuses within  it is pumped into the deep veins; and when the  muscle relaxes, blood flows into the sinuses from  the superficial veins. Unidirectional blood flow  is maintained by the valves in the perforating  veins (Fig. 11.6).   • "Cut open procedure"/venesection is done on  the great saphenous vein as it lies in front of  medial malleolus. This vein is used for  transfusion of blood/fluids in case of non¬  availability or collapse of other veins. Saphenous  nerve is identified and not injured as it lies  anterior to the great saphenous vein (Fig. 11.7).   • Great saphenous vein is used for bypassing the  blocked coronary arteries. The vein is reversed  so that valves do not block the passage of blood.   • Varicose veins and ulcers: If the valves in per¬  forating veins or at the termination of superficial  veins become incompetent, the defective veins  become "high pressure leaks" through which the  high pressure of the deep veins produced by  muscular contraction is transmitted to the  superficial veins. This results in dilatation of the  superficial veins and to gradual degeneration of  their walls producing varicose veins and varicose  ulcers (Fig. 11.8).    • Varicose veins often occur during third trimester  of pregnancy, as the iliac vein get pressed due to  enlarged uterus. These mostly subside after  delivery.   • Trendelenburg's test: This is done to find out the  site of leak or defect in a patient with varicose  veins. Only the superficial veins and the  perforating veins can be tested, not the deep veins.   • The patient is made to lie down, and the veins  are emptied by raising the limb and stroking the  varicose veins in a proximal direction. Now  pressure is applied with the thumb at the  saphenofemoral junction and the patient is asked  to stand up quickly. To test the superficial veins,  the pressure is released. Quick filling of the  varicose veins from above indicates incompetency  of the superficial veins.   To test the perforating veins, the pressure at the  saphenofemoral junction is not released, but  maintained for about a minute. Gradual filling  of the varices indicates incompetency of the  perforating veins, allowing the blood to pass  from deep to superficial veins.   • After a deep vein thrombosis affecting the  perforators, they recanalise without valves. So  the muscle pump will force blood from deep to  superficial veins, causing varicosity of the veins.   • Varicose veins are treated with sclerosing  injections or laser treatment.   Comparison between long saphenous and short  saphenous veins is as follows.   Most of the lymph from the lower limb drains into  the inguinal lymph nodes, either mostly directly or  partly indirectly through the popliteal and anterior  tibial nodes. The deep structures of the gluteal region  and the upper part of the back of the thigh drain into  the internal iliac nodes along the gluteal vessels.   These are very important because they drain the skin  and fasciae of the lower limb; the perineum and the  trunk below the umbilical plane ( see Fig. 3.5). They are  divided into three sets.   1 The lower vertical group is placed along both sides of  the terminal part of the great saphenous vein, and  contains about four or five nodes. They drain the skin  and fasciae of the lower limb (great saphenous  territory), except the buttock and the short saphenous  territory. A few lymphatics, accompanying the short  saphenous vein, cross the leg, accompany the great  saphenous vein, and drain into this group of nodes.   2 The upper lateral group is placed below the lateral part  of the inguinal ligament, and contains about two or  three nodes. They drain the skin and fasciae of the  upper part of the lateral side of the thigh, the buttock,  the flank and the back below the umbilical plane.   3 The upper medial group is placed below the medial  end of the inguinal ligament. One or two nodes may  lie above the inguinal ligament along the course of  the superficial epigastric vessels. The group contains  two to three nodes. They drain:   a. The anterior abdominal wall below the level of  the umbilicus.   b. The perineum, including external genitalia, except  the glans, the anal canal below the pectinate line,  the vagina below hymen and the penile part of  the male urethra.   c. The superolateral angle of the uterus, via the  round ligament.   Efferents from all superficial inguinal nodes pierce the  cribriform fascia, and terminate in the deep inguinal  nodes. A few may pass directly to the external iliac nodes.   These are about four to five in number, and lie medial  to the upper part of the femoral vein. The most proximal  node of this group; gland of Cloquet or of Rosenmuller,  lies in the femoral canal. These nodes receive afferents  from:   4 The deep lymphatics of the lower limb accompanying  the femoral vessels.    VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS   These nodes lie near the termination of the small  saphenous vein, deep to the deep fascia. One node lies  between the popliteal artery and the oblique popliteal  ligament. They receive afferents from:   2 The deep parts of the leg (through vessels running  along the anterior and posterior tibial vessels).   Their efferents run along the popliteal and femoral  vessels, and terminate in the deep inguinal nodes.   One inconstant node may lie along the upper part of  the anterior tibial artery. When present, it collects lymph  from the anterior compartment of the leg, and passes it  on to the popliteal nodes.   These lymph vessels are larger and are more numerous  than the deep lymphatics. They run in the superficial  fascia and ultimately form two streams. The main  stream follows the great saphenous vein, and ends in  the lower vertical group of superficial inguinal lymph    nodes shown in (Fig. 11.9a). The accessory stream  follows the small saphenous vein and ends in the  popliteal lymph nodes (Fig. 11.9b).   These are smaller and fewer than the superficial  lymphatics, although they drain all structures lying deep  to the deep fascia. They run along the principal blood  vessels, and terminate mostly into the deep inguinal  nodes, either directly or indirectly through the popliteal  nodes. The deep lymphatics from the gluteal region and  from the upper part of the back of the thigh accompany  the gluteal vessels and end in the internal iliac nodes.    • Elephantiasis: Lymphatic obstruction caused by the  parasite filaria is very common in the lower limb.  This results in great hypertrophy of the skin and  of subcutaneous tissue (elephantiasis) (Fig. 11.10).   • The commonest cause of a swelling in the inguinal  area is enlargement of the inguinal lymph nodes.  This can be caused by infection, or carcinoma,  anywhere in the area drained by these nodes  (Fig. 11.11).    Figs 11.9a and b: Superficial lymphatics of the lower limb: (a) Anterior aspect, and (b) posterior aspect   The principles involved are the same as described in  the upper limb.   The area of skin supplied by one spinal segment is  called a dermatome.   j a. Mainly from segments LI to L5 and SI to S3 of  the spinal cord; and  b. Partly from segments T12 and S4.   2 As a rule, the limb is supplied only by anterior  primary rami. The exception to this rule is that the  skin of the superomedial quadrant of the gluteal  region is supplied by the posterior primary rami of  nerves LI to L3 and SI to S3.    3 There is varying degree of overlap of adjoining  dermatomes, so that the area of sensory loss  following damage to the spinal cord or nerve roots  is always less than the actual area of the dermatome.   4 Initially, each limb bud has a cephalic border, and a  caudal border. These are known as the preaxial and  the postaxial borders, respectively. In the embryo, the  great toe and tibia lie along the preaxial border, and  the little toe and fibula along the postaxial border.  Later, the limb bud rotates medially through 90°, so  that the great toe and tibia are carried medially, and  the little toe and fibula laterally. Thus, the tibial  border is the original preaxial border, and the fibular  border, the postaxial border, of the lower limb.   5 The dermatomes of the lower limb are distributed in  an orderly numerical sequence (Figs 11.12a and b).   Figs 11.12a and b: Dermatomes of the lower limb: (a) Anterior  view, and (b) posterior view    Along the preaxial border from above downwards,  there are dermatomes T12, LI to L4.   The middle three toes, the adjoining area of the  dorsum of the foot and the lateral side of the leg are  supplied by segment L5.   Along the postaxial border from below upwards,  there are dermatomes SI, S2, S3.   6 As the limb elongates, the central dermatomes (L4,  L5, SI) get pulled in such a way that these are   VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS   represented only in the distal part of the limb, and  are buried proximally. The line along which the  central dermatomes are buried is known as the axial  line. In fact, an axial line is defined as a line along  which certain dermatomes are buried (missing) so  that distant dermatomes adjoin each other.  Overlapping of the dermatomes is minimal across  the axial line. There are two axial lines, one ventral  and one dorsal, both of which extend largely on the  back of the limb. On the posterior surface of the limb,  the ventral axial line extends up to the heel, whereas  the dorsal axial line ends at a higher level, at the junction  of the upper two-thirds and lower one-third of the  leg. On the anterior surface of the limb, the ventral  axial line crosses the scrotum, and the dorsal axial line  encroaches on the lateral side of the knee. Some  workers deny the existence of the dorsal axial line.   A spinal nerve supplies muscles that are derived from  one myotome. Most of the muscles are supplied by  more than one segment of the spinal cord, the supply  by some segments being predominant. Damage of the  predominant segments results in maximum paralysis  of the muscle. The chart given below is accurate enough  for use in clinical examination.   L2 Psoas major, iliacus, sartorius, gracilis, pectineus,  adductor longus, adductor brevis.   L3 Quadriceps, adductors (longus, brevis, magnus).  L4 Quadriceps, tensor fasciae latae, adductor  magnus, obturator externus, tibialis anterior,  tibialis posterior.   L5 Gluteus medius, gluteus minimus, obturator  intemus, semimembranosus, semitendinosus,  extensor hallucis longus, extensor digitorum  longus, peroneus tertius, popliteus.   51 Gluteus maximus, obturator intemus, piriformis,  biceps femoris, semitendinosus, popliteus,  gastrocnemius, soleus, peronei, extensor  digitorum brevis.   52 Piriformis, biceps femoris, gastrocnemius, soleus,  flexor digitorum longus, flexor hallucis longus,  intrinsic muscles of foot.   53 Intrinsic muscles of foot (except abductor  hallucis, flexor hallucis brevis, flexor digitorum  brevis, extensor digitorum brevis).   The segmental innervation of muscles can also be  expressed in terms of movements of joints (Fig. 11.13).  Hip Flexors, adductors and    Like dermatomes, the myotomes are also helpful in  determination of the level of a lesion in the spinal cord.   1 Sympathetic innervation of the lower limb is derived  from the lower three thoracic and upper two lumbar  (T10 to L2) segments of the spinal cord. The fibres  arise from the lateral horn cells, and pass out with  the ventral roots as preganglionic (white rami) fibres.  These pass down the sympathetic chain to relay in  the lumbar and upper two or three sacral ganglia.   2 The postganglionic fibres emerge from the lumbar  sympathetic ganglia and pass through grey rami to  reach the lumbar nerves. From these nerves they pass  into the femoral nerve. They supply the femoral  artery and its branches in the thigh. Some  postganglionic sympathetic fibres emerge from the  upper two or three sacral ganglia. They travel  through the tibial nerve to supply the popliteal artery  and its branches in the leg and foot.   3 The blood vessels to skeletal muscles are dilated by  sympathetic activity. These nerves are vasomotor,  sudomotor and pilomotor to the skin.   4 Sympathetic denervation of the lower limb can be  produced by removing the second, third and fourth  lumbar ganglia with the intermediate chain. This  divides all preganglionic fibres to the lower limb.  The first lumbar ganglion is preserved because it  controls the proximal urethral sphincter mechanism.  Its removal is followed by dry coitus. Bilateral  lumbar sympathectomy is done in patients with  Buerger's disease.   M —Medial end of dorsal venous arch  m—medial marginal vein ends into it  m —lies anterior to the medial malleolus  m—crosses medial surface of tibia obliquely  m —runs behind medial border of tibia to reach  behind the knee   Lower limb with long and heavy bones supports The upper limb is for range and variety of movements,  and stabilises the body Thumb assisted by palm and fingers has the power of holding    Lower limb bud rotates medially, so that big toe  points medially. Nerve supply: Ventral rami of  lumbar 2-5 and sacral 1 -3 segments of spinal cord.  Sciatic and one of its terminal branch the tibial  nerve supplies the flexor aspect of the limb. The  other terminal branch of sciatic nerve, i.e. common  peroneal, supplies the extensors of ankle joint  (dorsiflexors) through its deep peroneal branch. Its  superficial branch supplies the peroneal muscles  of the leg. Femoral supplies the quadriceps femoris  (extensor of knee) while obturator nerve supplies  the adductors    Upper limb bud rotates laterally, so that the thumb points  laterally. Nerve supply: Ventral rami of cervical 5-8 and thoracic  1 segments of spinal cord. Musculocutaneous, median and  ulnar nerves supply the flexor aspects of the limb, while the  radial nerve supplies the triceps brachii (extensor of elbow)  and its branch the posterior interosseous supplies the  extensors of wrist    Femur is the longest bone of lower limb and of the Humerus is the longest bone of upper limb  body    Posteriorly: Hamstrings supplied by sciatic  Anteriorly: Quadriceps by femoral  Medially: Adductors by obturator nerve   VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS    Sciatic for posterior compartment of thigh, femoral  for anterior compartment of thigh, obturator for  adductor muscles of medial compartment of thigh    Musculocutaneous for anterior compartment of arm  Radial for posterior compartment. Coracobrachialis equivalent  to medial compartment of arm also supplied by musculo¬  cutaneous nerve    Femoral, popliteal and profunda femoris (deep) Axillary, brachial, profunda (deep) brachii    Knee joint formed by femur, tibia and patella. Fibula  does not participate in knee joint. An additional  bone (sesamoid) patella makes its appearance.  This is an important weight-bearing joint   Flexor digitorum longus  Flexor hallucis longus  Soleus and flexor digitorum brevis  Gastrocnemius (medial head)  Gastrocnemius (lateral head)  Tibialis anterior  Extensor digitorum longus  Extensor hallucis longus    Elbow joint formed by humerus, radius and ulna, communi¬  cates with superior radioulnar joint. Forearm is characterised  by superior and inferior radioulnar joints. These are both pivot  variety of synovial joints permitting rotatory movements of  pronation and supination, e.g. meant for picking up food and  putting it in the mouth   Palmaris longus  Flexor digitorum profundus  Flexor pollicis longus  Flexor digitorum superficialis  Flexor carpi ulnaris  Flexor carpi radialis  Abductor pollicis longus  Extensor digitorum  Extensor pollicis longus    Anterior aspect: Dorsiflexors of ankle joint  Posterior aspect: Plantar flexors (flexors) of ankle  joint   Tibial nerve for all the plantar flexors of the ankle  joint. Common peroneal winds around neck of  fibula (postaxial bone) and divides into superficial  and deep branches. The deep peroneal supplies  dorsiflexors (extensors) of the ankle joint. The  superficial peroneal nerve supplies a separate  lateral compartment of leg    Anterior aspect: Flexors of wrist and pronators of forearm  Posterior aspect: Extensors of wrist, and supinator    Median nerve for 6 V 2 muscles and ulnar nerve for IY 2 muscles  of anterior aspect of forearm. These are flexors of wrist and  pronators of forearm. Posterior interosseous nerve or deep  branch of radial supplies the extensors of the wrist and the  supinator muscle of forearm. It winds around radius (preaxial  bone) and corresponds to deep peroneal nerve. The superficial  branch of radial nerve corresponds to the superficial peroneal  nerve    Popliteal divides into anterior tibial and posterior Brachial divides into radial and ulnar branches in the cubital  tibial in the popliteal fossa. Posterior tibial fossa. Radial corresponds to anterior tibial artery  corresponds to ulnar artery    7 big tarsal bones occupying half of the foot. There  are special joints between talus, calcaneus and  navicular, i.e. subtalar and talocalcaneonavicular  joints. They permit the movements of inversion  and eversion (raising the medial border/lateral  border of the foot) for walking on the uneven  surfaces. This movement of inversion is similar to  supination and of eversion to pronation of forearm.  Flexor digitorum accessorius is a distinct muscle    There are 8 small carpal bones occupying very small area of  the hand. First carpometacarpal joint, i.e. joint between  trapezium and base of 1st metacarpal is a unique joint. It is of  saddle variety and permits a versatile movement of opposition  in addition to other movements. This permits the hand to hold  things, e.g. doll, pencil, food, bat, etc. Opponens pollicis is  specially for opposition    to straighten the action of flexor digitorum longus  tendons in line with the toes on which these act.  Tibialis anterior, tibialis posterior and peroneus  longus reach the foot and sole for the movements  of inversion (first two) and eversion (last one)  respectively   Medial plantar supplies four muscles of the sole  including 1st lumbrical (abductor hallucis, flexor  hallucis brevis, flexor digitorum brevis, 1st  lumbrical) f   Muscles which enter the sole from the leg, e.g.  flexor digitorum longus, flexor hallucis longus,  tibialis posterior, peroneus longus are supplied by  the nerves of the leg. 1st lumbrical is unipennate  and is supplied by medial plantar, 2nd-4th are  bipennate being supplied by deep branch of lateral  plantar nerve   Posterior tibial artery divides into medial plantar and  lateral plantar branches. There is only one arch,  the plantar arch formed by lateral plantar and  dorsalis pedis (continuation of anterior tibial)  arteries   The great sphenous vein with perforators lies along  the preaxial border. The short saphenous vein, lies  along the postaxial border but it terminates in the  popliteal fossa   The axis of movement of adduction and abduction  passes through the 2nd digit. So 2nd toe possesses  two dorsal interossei muscles    Median nerve supplies 5 muscles of hand including 1st and  2nd lumbricals (abductor pollicis brevis, flexor pollicis brevis,  opponens pollicis, 1st and 2nd lumbricals)   Ulnar nerve corresponds to lateral plantar nerve and supplies  15 intrinsic muscles of the hand   Muscles which enter the palm from forearm, e.g. flexor  digitorum superficialis, flexor digitorum profundus, flexor pollicis  longus are supplied by the nerves of the forearm. 1st and 2nd  lumbricals are unipennate and are supplied by median nerve.  3rd and 4th are bipennate being supplied by deep branch of  ulnar nerve   Radial artery corresponds to anterior tibial while ulnar artery  corresponds to posterior tibial artery. Ulnar artery divides into  superficial and deep branches. There are two palmar arches,  superficial and deep. The superficial arch mainly is formed by  ulnar artery and deep arch is formed mainly by the radial  artery. Cephalic vein is along the preaxial border. Basilic vein  runs along the postaxial border of the limb and terminates in  the middle of the arm   The axis of movement of adduction and abduction is through  the third digit or middle finger. So the middle finger has two  dorsal interossei muscles   Superficial plantar arch is not present  Branches of medial plantar nerve and artery  Branches of superficial branch of lateral plantar  nerve   Tendon of flexor digitorum longus, lumbricals and  flexor digitorum accessorius  Tendon of flexor hallucis longus   Abductor pollicis brevis  Flexor pollicis brevis  Flexor digiti minimi  Abductor digiti minimi   VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS    Sciatic for posterior compartment of thigh, femoral  for anterior compartment of thigh, obturator for  adductor muscles of medial compartment of thigh    Musculocutaneous for anterior compartment of arm  Radial for posterior compartment. Coracobrachialis equivalent  to medial compartment of arm also supplied by musculo¬  cutaneous nerve    Femoral, popliteal and profunda femoris (deep) Axillary, brachial, profunda (deep) brachii   Knee joint formed by femur, tibia and patella. Fibula  does not participate in knee joint. An additional  bone (sesamoid) patella makes its appearance.  This is an important weight-bearing joint   Flexor digitorum longus  Flexor hallucis longus  Soleus and flexor digitorum brevis  Gastrocnemius (medial head)  Gastrocnemius (lateral head)  Tibialis anterior  Extensor digitorum longus  Extensor hallucis longus   Elbow joint formed by humerus, radius and ulna, communi¬  cates with superior radioulnar joint. Forearm is characterised  by superior and inferior radioulnar joints. These are both pivot  variety of synovial joints permitting rotatory movements of  pronation and supination, e.g. meant for picking up food and  putting it in the mouth   Palmaris longus  Flexor digitorum profundus  Flexor pollicis longus  Flexor digitorum superficialis  Flexor carpi ulnaris  Flexor carpi radialis  Abductor pollicis longus  Extensor digitorum  Extensor pollicis longus    Anterior aspect: Dorsiflexors of ankle joint  Posterior aspect: Plantar flexors (flexors) of ankle  joint   Tibial nerve for all the plantar flexors of the ankle  joint. Common peroneal winds around neck of  fibula (postaxial bone) and divides into superficial  and deep branches. The deep peroneal supplies  dorsiflexors (extensors) of the ankle joint. The  superficial peroneal nerve supplies a separate  lateral compartment of leg    Anterior aspect: Flexors of wrist and pronators of forearm  Posterior aspect: Extensors of wrist, and supinator    Median nerve for 6 V 2 muscles and ulnar nerve for 1 Yz muscles  of anterior aspect of forearm. These are flexors of wrist and  pronators of forearm. Posterior interosseous nerve or deep  branch of radial supplies the extensors of the wrist and the  supinator muscle of forearm. It winds around radius (preaxial  bone) and corresponds to deep peroneal nerve. The superficial  branch of radial nerve corresponds to the superficial peroneal  nerve    Popliteal divides into anterior tibial and posterior Brachial divides into radial and ulnar branches in the cubital  tibial in the popliteal fossa. Posterior tibial fossa. Radial corresponds to anterior tibial artery  corresponds to ulnar artery    7 big tarsal bones occupying half of the foot. There  are special joints between talus, calcaneus and  navicular, i.e. subtalar and talocalcaneonavicular  joints. They permit the movements of inversion  and eversion (raising the medial border/lateral  border of the foot) for walking on the uneven  surfaces. This movement of inversion is similar to  supination and of eversion to pronation of forearm.  Flexor digitorum accessorius is a distinct muscle    There are 8 small carpal bones occupying very small area of  the hand. First carpometacarpal joint, i.e. joint between  trapezium and base of 1st metacarpal is a unique joint. It is of  saddle variety and permits a versatile movement of opposition  in addition to other movements. This permits the hand to hold  things, e.g. doll, pencil, food, bat, etc. Opponens pollicis is  specially for opposition   to straighten the action of flexor digitorum longus  tendons in line with the toes on which these act.  Tibialis anterior, tibialis posterior and peroneus  longus reach the foot and sole for the movements  of inversion (first two) and eversion (last one)  respectively   Medial plantar supplies four muscles of the sole  including 1 st lumbrical (abductor hallucis, flexor  hallucis brevis, flexor digitorum brevis, 1 st  lumbrical) /   Muscles which enter the sole from the leg, e.g.  flexor digitorum longus, flexor hallucis longus,  tibialis posterior, peroneus longus are supplied by  the nerves of the leg. 1 st lumbrical is unipennate  and is supplied by medial plantar, 2 nd- 4 th are  bipennate being supplied by deep branch of lateral  plantar nerve   Posterior tibial artery divides into medial plantar and  lateral plantar branches. There is only one arch,  the plantar arch formed by lateral plantar and  dorsalis pedis (continuation of anterior tibial)  arteries   The great sphenous vein with perforators lies along  the preaxial border. The short saphenous vein, lies  along the postaxial border but it terminates in the  popliteal fossa   The axis of movement of adduction and abduction  passes through the 2nd digit. So 2 nd toe possesses  two dorsal interossei muscles    Superficial plantar arch is not present  Branches of medial plantar nerve and artery  Branches of superficial branch of lateral plantar  nerve   Tendon of flexor digitorum longus, lumbricals and  flexor digitorum accessorius  Tendon of flexor hallucis longus    Median nerve supplies 5 muscles of hand including 1st and  2 nd lumbricals (abductor pollicis brevis, flexor pollicis brevis,  opponens pollicis, 1 st and 2 nd lumbricals)   Ulnar nerve corresponds to lateral plantar nerve and supplies  15 intrinsic muscles of the hand   Muscles which enter the palm from forearm, e.g. flexor  digitorum superficialis, flexor digitorum profundus, flexor pollicis  longus are supplied by the nerves of the forearm. 1 st and 2 nd  lumbricals are unipennate and are supplied by median nerve.  3rd and 4th are bipennate being supplied by deep branch of  ulnar nerve   Radial artery corresponds to anterior tibial while ulnar artery  corresponds to posterior tibial artery. Ulnar artery divides into  superficial and deep branches. There are two palmar arches,  superficial and deep. The superficial arch mainly is formed by  ulnar artery and deep arch is formed mainly by the radial  artery. Cephalic vein is along the preaxial border. Basilic vein  runs along the postaxial border of the limb and terminates in  the middle of the arm   The axis of movement of adduction and abduction is through  the third digit or middle finger. So the middle finger has two  dorsal interossei muscles   Abductor pollicis brevis  Flexor pollicis brevis  Flexor digiti minimi  Abductor digiti minimi    VENOUS AND LYMPHATIC DRAINAGE AND COMPARISON OF LOWER AND UPPER LIMBS    • Long saphenous vein with saphenous nerve lie  anterior to medial malleolus   • Varicose veins are due to tortuosity of the long  saphenous vein and occur mostly due to prolonged  standing.   • Long saphenous vein is used to bypass the  coronary artery after inverting the vein.    A 30-year-old female during her pregnancy noted  blue tubular structures over her calf and thigh. These  get prominent after standing for a long time.   Ans: These blue tubular structures are the varicose  veins in the lower limbs. These develop due to  pressure of the foetal head on the veins in the pelvis,  preventing the return of venous blood back into the  circulation. These develop only in lower limbs as  venous blood has to flow against gravity. Though  there are valves inside the vein to permit  unidirectional flow of blood, still varicose veins  develop due to some incompetency of the valves and  the pressure of the foetal head. On prolonged stan-  d ing the veins got more prominent, as venous blood  has to travel vertically upwards for long distance.  Varicose veins usually disappear after pregnancy.    1. Which one of the following factors does not help in   c. Compression of vena comitantes accompanying  the arteries by arterial pulsation   d. Presence of valves which supports the long  column of blood and divides the long column  into shorter parts.   4. Posterior primary rami of L1-L3 and S1-S3 supply  skin of which quadrant of the gluteal region?   1. a b 3. d 4. b 5. a 6. b   The weight-bearing joints of the lower limb are more  stable. Hip joint allows the same movement as the  mobile shoulder joint, but the range of movement is  restricted.   Knee joint allows similar movements as the elbow  besides the very important locking of the joint for long  time standing. The leg bones do not permit the  movements of supination and pronation for reasons of  stability.   The ankle joint also allows limited movements for  the same reason. The additional movements of  inversion and eversion provided at the subtalar joints  are to adjust the foot to the uneven ground.   Ligate the femoral vessels and nerve with thick thread  2 cm below the inguinal ligament. Cut them above the  ligature.   Cut sartorius muscle 5 cm below its origin and rectus  femoris 3 cm below its origin and reflect these  downwards. Detach the iliopsoas muscle from its  insertion into lesser trochanter and separate the two  parts.   The capsule of the joint and the thickened iliofemoral  ligament are now exposed. Supplement the study of  the ligaments and movements on the dried bones.   of the hip bone to form the hip joint. The head of the    femur forms more than half a sphere, and is covered  with hyaline cartilage except at the fovea capitis. The  acetabulum presents a horseshoe-shaped, lunate  articular surface, an acetabular notch and an acetabular  fossa (Figs 12.1a and b). The lunate surface is covered  with cartilage. Though the articular surfaces on the head  of the femur and on the acetabulum are reciprocally  curved, they are not co-extensive.    The hip joint is unique in having a high degree of  stability as well as mobility. The stability or strength  depends upon:   a. Depth of the acetabulum and the narrowing of its  mouth by the acetabular labrum.   e. Atmospheric pressure: A fairly wide range of  mobility is possible because of the fact that the  femur has a long neck which is narrower than the  equatorial diameter of the head.   1 The fibrous capsule is attached on the hip bone to the  acetabular labrum including the transverse  acetabular ligament, and to bone above and behind  the acetabulum; and on the femur to the inter¬  trochanteric line in front, and 1 cm medial to the  intertrochanteric crest behind (Fig. 12.2).    Anterosuperiorly, the capsule is thick and firmly  attached. This part is subjected to maximum tension  in the standing posture. Posteroinferiorly, the capsule  is thin and loosely attached to bone.   The capsule is made up of two types of fibres. The  outer fibres are longitudinal and the inner circular  ones are called as zona orbicularis. The longitudinal  fibres are best developed anterosuperiorly, where  many of them are reflected along the neck of the  femur to form the retinacula. Blood vessels supplying  the head and neck of the femur, travel along these  retinacula. The synovial membrane lines the fibrous  capsule, the intracapsular portion of the neck of the  femur, both surfaces of the acetabular labrum, the  transverse ligament, and fat in the acetabular fossa.  It also invests the round ligament of the head of the  femur (Fig. 12.2).   The joint cavity communicates with a bursa  lying deep to the tendon of psoas major, through a  circular opening in the capsule located between the   2 The iliofemoral ligament , or inverted Y-shaped  ligament of Bigelow , lies anteriorly. It is one of the  strongest ligaments in the body. It prevents the trunk  from falling backwards in the standing posture. The  ligament is triangular in shape. Its apex is attached  to the lower half of the anterior inferior iliac spine;  and the base to the intertrochanteric line. The upper  oblique and lower vertical fibres form thick and  strong bands, while the middle fibres are thin and  weak (Fig. 12.3).    3 The pubofemoral ligament supports the joint  inferomedially. It is also triangular in shape.  Superiorly, it is attached to the iliopubic eminence,  the obturator crest and the obturator membrane.  Interiorly, it merges with the anteroinferior part of  the capsule and with the lower band of the  iliofemoral ligament.   4 The ischiofemoral ligament is comparatively weak. It  covers the joint posteriorly. Its fibres are twisted and  extend from the ischium to the acetabulum. The  fibres of the ligament form the zona orbicularis. Some  of them are attached to the greater trochanter  (Fig. 12.4).   5 The ligament of the head of the femur, round ligament  or ligamentum teres is a flat and triangular ligament.  The apex is attached to the fovea capitis, and the  base to the transverse ligament and the margins of  the acetabular notch. It may be very thin, or even  absent. It transmits arteries to the head of the femur,  from the acetabular branches of the obturator and  medial circumflex femoral arteries (see Fig. 4.7).   6 The acetabular labrum is a fibrocartilaginous rim  attached to the margins of the acetabulum. It narrows  the mouth of the acetabulum. This helps in holding  the head of the femur in position (Fig. 12.5).   7 The transverse ligament of the acetabulum is a part of  the acetabular labrum which bridges the acetabular    notch. The notch is thus converted into a foramen  which transmits acetabular vessels and nerves to the  joint (Figs 12.1 and 12.5).   Tendon of the iliopsoas separated from the joint  by a bursa and femoral vein, femoral artery and femoral  nerve (Fig. 12.5).   The joint, from below upwards, is related to the  following muscles: Tendon of obturator externus  covered by the quadratus femoris, obturator intemus  and gemelli, piriformis, sciatic nerve and the gluteus  maximus muscle.   Reflected head of the rectus femoris covered by the  gluteus minimus, gluteus medius and partly by gluteus  maximus.   Lateral fibres of the pectineus and the obturator  externus. In addition there are gracilis, adductors  longus, brevis, magnus and hamstring muscles.   The hip joint is supplied by the obturator artery, two  circumflex femorals and two gluteal arteries. The  medial and lateral circumflex femoral arteries form an  arterial circle around the capsular attachment on the  neck of the femur. Retinacular arteries arise from this  circle and supply the intracapsular part of the neck and  the greater part of the head of the femur. A small part  of the head, near the fovea capitis is supplied by the  acetabular branches of the obturator and medial  circumflex femoral arteries (see Fig. 4.7).   Ligament of head of femur  Femoral nerve  Femoral artery  Femoral vein   The hip joint is supplied by the femoral nerve, through  the nerve to the rectus femoris; the anterior division of  the obturator nerve; the nerve to the quadratus femoris;  and the superior gluteal nerve.   Hip joint extension and slight abduction and medial  rotation is the close packed position for the hip joint  which means the ligaments and the capsules are most  taut in this position. But the surfaces are most congruent  in slightly flexed, abducted and laterally rotated  position of the hip.   In general, all axes pass through the centre of the  head of the femur, but none of them is fixed because  the head is not quite spherical.   Flexion is limited by contact of the thigh with the  anterior abdominal wall. Similarly, adduction is limited  by contact with the opposite limb. The range of the other  movements is different from one another: Extension 15°,  abduction 50°, medial rotation 25°, and lateral rotation  60°.   The movement of the hip is closely related to the  position of the knee because of the presence of two  muscles which act on both hip and knee. In the extended  position of the knee, the stretch on the hamstring  muscles does not allow the hip to move into its complete  flexion range. Similarly with knee completely flexed,  the hip joint may not attain complete extension due to  tension in the Rectus femoris which gets stretched at  the hip and the knee.   When the hip joints are bearing weight, the femur is  fixed. But like any other joint, here also the proximal    bone, i.e. pelvis is capable of moving on the fixed distal  femur. The pelvis can either move into anterior tilting  (equivalent to flexion of hip) or posterior tilting  (equivalent to extension of the hip).    * Congenital dislocation is more common in the  hip than in any other joint of the body. The head  of the femur slips upwards on to the gluteal  surface of the ilium because the upper margin of  the acetabulum is developmentally deficient  (Fig. 12.6). This causes lurching gait, and  Trendelenburg's test is positive ( see Fig. 5.12).   * Perthes' disease or pseudocoxalgia is characterized  by destruction and flattening of the head of the  femur, with an increased joint space in X-ray  pictures.   Coxa vara is a condition in which the neck-shaft  angle is reduced from the normal angle of about  150° in a child, and 127° in an adult (Fig. 12.7).   * Dislocation of the hip may be posterior (more  common), anterior (less common), or central  (rare). The sciatic nerve may be injured in posterior  dislocations.   * Injuries in the region of hip joint may produce  shortening of the lower limb. The length of lower  limb is measured from the anterior superior iliac  spine to the medial malleolus.   * Disease of the hip like tuberculosis, may cause  referred pain in the knee because of the common  nerve supply of the two joints.   * Aspiration of the hip joint can be done by passing a  needle from a point 5 cm below the anterior  superior iliac spine, upwards, backwards and  medially. It can also be done from the side by  passing the needle from the posterior edge of the  greater trochanter, upwards and medially, parallel  with the neck of the femur.   Gluteus maximus and hamstrings  Adductors longus, brevis and magnus  Glutei medius and minimus   Tensor fasciae latae and the anterior fibres of the glutei  medius and minimus   Pectineus, rectus femoris, and sartorius;  adductors (mainly adductor longus) participate  in early stages   • In arthritis of hip joint, the position of joint is  partially flexed, abducted and laterally rotated.   • Fracture of the neck of the femur may be  subcapital, near the head (Fig. 12.8), cervical in the  middle, or basal near the trochanters. Damage to  retinacular arteries causes avascular necrosis of  the head. Such a damage is maximal in subcapital  fractures and least in basal fractures. These  fractures are common in old age, between the age  of 40 and 60 years. Femur neck fracture is usually  produced by trivial injuries.   Trochanteric fracture may be intertrochanteric, i.e.  between the trochanters or subtrochanteric, i.e.  below the trochanters. These fractures occur in  strong, adult subjects, and are produced by severe,  violent injuries (Fig. 12.8).   • Shenton's line, in an X-ray picture, is a continuous  curve formed by the upper border of the obturator  foramen and the lower border of the neck of the  femur. In fracture neck femur, line becomes  abnormal (Fig. 12.9).   Strip the extra structures around the knee joint, leaving  behind the fibrous capsule, ligaments and parts of  muscles/tendons attached to the bones/ligaments.   Study the articular surfaces, articular capsule, medial  and lateral collateral ligaments, oblique popliteal  ligament and arcuate popliteal ligament.   The knee is the largest and most complex joint of the  body. The complexity is the result of fusion of three  joints in one. It is formed by fusion of the lateral   3 The condyles of the tibia. The femoral condyles  articulate with the tibial condyles below and behind,  and with the patella in front.   It is condylar synovial joint, incorporating two condylar  joints between the condyles of the femur and tibia, and  one saddle joint between the femur and the patella. It  is also a complex joint as the cavity is divided by the  menisci.    Capsular ligament blending with  deep part of the ligament and  with medial meniscus   The fibrous capsule is very thin, and is deficient  anteriorly, where it is replaced by the quadriceps  femoris, the patella and the ligamentum patellae.   Femoral attachment: It is attached about half to one  centimeter beyond the articular margins. The  attachment has three special features.   Tibial attachment: It is attached about half to one  centimeter beyond the articular margins. The attachment  has three special features.   1 Anteriorly, it descends along the margins of the  condyles to the tibial tuberosity, where it is deficient.   2 Posteriorly, it is attached to the intercondylar ridge  which limits the attachment of the posterior cruciate  ligament.   3 Posterolaterally, there is a gap behind the lateral  condyle for passage of the tendon of the popliteus.  Some terms applied to parts of the capsule are as   Coronary ligament: The fibrous capsule is attached to  the periphery of the menisci. The part of the capsule  between the menisci and the tibia is sometimes called  the coronary ligament.   Short lateral ligament: This is a cord-like thickening of  the capsule deep to the fibular collateral ligament. It  extends from the lateral epicondyle of femur, where it  blends with the tendon of popliteus, to the medial  border of the apex of the fibula.   The capsular ligament is weak. It is strengthened  anteriorly by the medial and lateral patellar retinacula,  which are extensions from the vastus medialis and  lateralis; laterally by the iliotibial tract; medially by  expansions from the tendons of the sartorius and  semimembranosus; and posteriorly, by the oblique  popliteal ligament.   2 Another for the exit of the tendon of the popliteus.  Sometimes there are gaps that communicate with the   bursae deep to the medial head of the gastrocnemius,  and deep to the semimembranosus.   This is the central portion of the common tendon of  insertion of the quadriceps femoris; the remaining  portions of the tendon form the medial and lateral  patellar retinacula. The ligamentum patellae is about  7.5 cm long and 2.5 cm broad. It is attached above to  the margins and rough posterior surface of the apex of  the patella, and below to the smooth , upper part of the  tibial tuberosity. The superficial fibres pass in front of  the patella. The ligamentum patellae is related to the  superficial and deep infrapatellar bursae, and to the  infrapatellar pad of fat (Fig. 12.12).   This is a long band of great strength. Superiorly, it is  attached to the medial epicondyle of the femur just  below the adductor tubercle. Inferiorly, it divides into  anterior and posterior parts.   The anterior or superficial part is about 10 cm long  and 1.25 cm broad, and is separated from the capsule  by one or two bursae. It is attached below to the medial  border and posterior part of the medial surface of the  shaft of the tibia. It covers the inferior medial genicular  vessels and nerve, and the anterior part of the tendon  of the semimembranosus, and is crossed below by the  tendons of the sartorius, gracilis and the semitendinosus  (Fig. 12.11).    Fig. 12.12: Sagittal section through the knee joint of right side  seen from the medial aspect to show the reflection of the synovial  membrane (note the cruciate ligaments)   The posterior (deep) part of the ligament is short and  blends with the capsule and with the medial meniscus.  It is attached to the medial condyle of the tibia above  the groove for the semimembranosus.   Morphologically, the tibial collateral ligament  represents the degenerated tendon of the adductor  magnus muscle.   This ligament is strong and cord-like. It is about 5 cm  long. Superiorly, it is attached to the lateral epicondyle  of the femur just above the popliteal groove. Interiorly,  it is embraced by the tendon of the biceps femoris, and  is attached to the head of the fibula in front of its apex.  It is separated from the lateral meniscus by the tendon  of the popliteus. It is free from the capsule. The inferior  lateral genicular vessels and nerve separate it from the  capsule (Fig. 12.11).   This is an expansion from the tendon of the  semimembranosus. It runs upwards and laterally,  blends with the posterior surface of the capsule, and is  attached to the intercondylar line and lateral condyle  of the femur. It is closely related to the popliteal artery,  and is pierced by the middle genicular vessels and  nerve, and the terminal part of the posterior division  of the obturator nerve (Fig 12.13).   This is a posterior expansion from the short lateral  ligament. It extends backwards from the head of the  fibula, arches over the tendon of the popliteus, and is  attached to the posterior border of the intercondylar  area of the tibia.   These are very thick and strong fibrous bands, which  act as direct bonds of union between tibia and femur, to  maintain anteroposterior stability of knee joint. They are  named according to the attachment on tibia.   Anterior cruciate ligament begins from anterior part  of intercondylar area of tibia, runs upwards, backwards  and laterally and is attached to the posterior part of  medial surface of lateral condyle of femur. It is taut  during extension of knee (Fig. 2.12).   Posterior cruciate ligament begins from the  posterior part of intercondylar area of tibia, runs  upwards, forwards and medially and is attached to  the anterior part of the lateral surface of medial  condyle of femur. It is taut during flexion of the knee.    These are supplied by middle genicular vessels and  nerves (see Figs 2.26 and 12.13).   The menisci are two fibrocartilaginous discs. They are  shaped like crescents. They deepen the articular  surfaces of the condyles of the tibia, and partially divide  the joint cavity into upper and lower compartments.  Flexion and extension of the knee take place in the upper  compartment, whereas rotation takes place in the lower  compartment (Fig. 12.11).   a. Two ends: The anterior and posterior ends of  menisci are attached to the tibia and are referred  to as anterior and posterior horns.   b. Two borders: The 'outer' border is thick, convex and  close to the fibrous capsule; while the 'inner'  border is thin, concave and free.   c. Two surfaces: The upper surface is concave for  articulation with the femur. The lower surface is  flat and rests on the peripheral two-thirds of the  tibial condyle. The peripheral thick part is  vascular. The inner part is avascular and is  nourished by synovial fluid.   The medial meniscus is nearly semicircular, being  wider behind than in front. The posterior fibres of the  anterior end are continuous with the transverse  ligament. Its peripheral margin is adherent to the deep  part of the tibial collateral ligament (Fig. 12.11).   The lateral meniscus is nearly circular (see Fig. 2.26).  The posterior end of the meniscus is attached to the  medial condyle of femur through two meniscofemoral  ligaments. The tendon of the popliteus and the capsule  separate this meniscus from the fibular collateral  ligament. The more medial part of the tendon of the  popliteus is attached to the lateral meniscus. The  mobility of the posterior end of this meniscus is  controlled by the popliteus and by the two  meniscofemoral ligaments.   Because of the attachments of the menisci to multiple  structures, the motion of the menisci is limited to a great  extent. Out of the two menisci the medial meniscus has  more firm attachments to the tibia.   In a young person the peripheral 25-33% of the  meniscus is vascularised and is innervated. The  remaining part of the meniscus receives its nutrition  from the synovial fluid. Therefore, movement is  important for cartilage nutrition since movement causes  diffusion of nutrients from synovial fluid to the  cartilage.   their contour to the varying curvature of the different  parts of the femoral condyles, as the latter glide over  the tibia.   4 Because of their nerve supply, they also have a  sensory function. They give rise to proprioceptive  impulses.   Cut through the tendon of quadriceps femoris muscle  just above the knee joint. Extend this incision on either  side of patella and ligamentum patellae anchored to the  tibial tuberosity. Reflect patella downwards to peep into  the cavity of knee joint.   Note the huge infrapatellar synovial fold and pad of  fat in it. Remove the fat and posterior part of fibrous  capsule so that the cruciate ligaments and menisci are  visualised.   The synovial membrane of the knee joint lines the  capsule, except posteriorly where it is reflected  forwards by the cruciate ligaments, forming a common  covering for both the ligaments (Figs 12.11 and 12.12).   In front, it is absent from the patella. Above the  patella, it is prolonged upwards for 5 cm or more as  the suprapatellar bursa. Below the patella, it covers the  deep surface of the infrapatellar pad of fat, which  separates it from the ligamentum patellae. A median  fold, the infrapatellar synovial fold, extends backwards  from the pad of fat to the intercondylar fossa of the  femur. An alar fold diverges on each side from the  median fold to reach the lateral edges of the patella  (Fig. 12.12).   As many as 12 bursae have been described around the  knee—four anterior, four lateral, and four medial. These  bursae are as follows.   1 A bursa deep to the lateral head of the gastrocnemius.   2 A bursa between the fibular collateral ligament and  the biceps femoris.   3 A bursa between the fibular collateral ligament and  the tendon of the popliteus.   4 A bursa between the tendon of the popliteus and the  lateral condyle of the tibia.   1 A bursa deep to the medial head of the gastroc¬  nemius.   2 The anserine bursa is a complicated bursa which  separates the tendons of the sartorius, the gracilis  and the semitendinosus from one another, from the  tibia, and from the tibial collateral ligament ( see  Fig. 8.14).   2 Posterolaterally: Lateral head of gastrocnemius,  plantaris, and common peroneal nerve.   3 Posteromedially: Medial head of gastrocnemius,  semitendinosus, semimembranosus, gracilis, and  popliteus at its insertion (Fig. 12.13).   5 The circumflex fibular branch of the posterior tibial  artery ( see Fig. 6.10).   Fig. 12,13: Transverse section through the left knee joint showing the synovial relations   1 Femoral nerve, through its branches to the vasti,  especially the vastus medialis.   2 Sciatic nerve, through the genicular branches of the  tibial and common peroneal nerves.   Clean the articular surfaces of femur, tibia and patella  on the soft specimen and on dried bones. Analyse the  movements on them. Try all these movements on  yourself and on your friends as well.   Active movements at the knee are flexion, extension,  medial rotation and lateral rotation (Table 12.2).   Flexion and extension are the chief movements. These  take place in the upper compartment of the joint, above    the menisci. They differ from the ordinary hinge  movements in two ways.   1 The transverse axis around which these move¬  ments take place is not fixed. During extension,  the axis moves forwards and upwards, and in the  reverse direction during flexion.   2 These movements are invariably accompanied by  rotations or conjunct rotation. When the foot is  on the ground, while standing erect, medial  rotation of femur occurs during last 30 degrees of  extension as in position of "attention" by the  vastus medialis. It is called conjunct rotation.  During the position of "stand at ease", there is  lateral rotation of femur, during initial stages of  flexion, by popliteus muscle.   Medial rotation of the femur occurs during the  last 30 degrees of extension, and lateral rotation of  the femur occurs during the initial stages of flexion.   When the foot is off the ground as while sitting  on a chair the tibia rotates instead of the femur, in  the opposite direction.   Rotatory movements at the knee are of a small range.  Rotations take place around a vertical axis, and are  permitted in the lower compartment of the joint, below  the menisci. Rotatory movements may be combined  with flexion and extension or conjunct rotations, or may  occur independently in a partially flexed knee or  adjunct rotations. The conjunct rotations are of value  in locking and unlocking of the knee.   During different phases of movements of the knee,  different portions of the patella articulate with the femur.  The lower pair of articular facets articulates during  extension; middle pair during beginning of flexion;  upper pair during midflexion; and the medial strip  during full flexion of the knee ( see Figs 2.21 and 12.10).   Locking is a mechanism that allows the knee to remain  in the position of full extension as in standing without  much muscular effort.   Locking occurs as a result of medial rotation of the  femur during the last stage of extension. The  anteroposterior diameter of the lateral femoral condyle  is less than that of the medial condyle. As a result, when  the lateral condylar articular surface is fully 'used up'  by extension, part of the medial condylar surface  remains unused. At this stage the lateral condyle serves  as an axis around which the medial condyle rotates  backwards, i.e. medial rotation of the femur occurs,  so that the remaining part of the medial condylar  surface is also 'taken up'. This movement locks the knee  joint. Locking is aided by the oblique pull of ligaments  during the last stages of extension. When the knee is  locked, it is completely rigid and all ligaments of  the joint are taut. Locking is produced by continued  action of the same muscles that produce extension, i.e.  the quadriceps femoris, especially the vastus medialis  part.   The locked knee joint can be flexed only after it is  unlocked by a reversal of the medial rotation, i.e. by  lateral rotation of the femur. Unlocking is brought about  by the action of the popliteus muscle.   Accessory or passive movements can be performed in a  partially flexed knee. These movements include:    3 Cruciate ligaments represent the collateral ligaments  of the originally separate femorotibial joints.   4 Infrapatellar synovial fold indicates the lower limit  of the femoropatellar joint.    • Osteoarthritis is an age related cartilage degene¬  ration of the articular surfaces. It is characterized  by growth of osteophytes at the articular ends,  which make movements limited and painful.  However, osteoarthritis may set in at an early age  also due to underlying congenital deformities or  fractures around the knee joint.   • Structurally, the knee is a weak joint because the  articular surfaces are not congruent. The tibial  condyles are too small and shallow to hold the  large, convex, femoral condyles in place. The  femoropatellar articulation is also quite insecure  because of the shallow articular surfaces, and  because of the outward angulation between the  long axis of the thigh and of the leg.   The stability of the joint is maintained by a number  of factors.   d. The iliotibial tract plays an important role in  stabilizing the knee ( see Fig. 3.8).   • Deformities of the knee: The angle between the long  axis of the thigh and that of the leg may be  abnormal and the leg may be abnormally abducted  (genu valgum or knock knee) or abnormally  adducted (genu varum or bow knee). This may  occur due to rickets, and posture, or as a congenital  abnormality (Fig. 12.14).   • Diseases of the knee: The knee joint may be affected  by various diseases. These include osteoarthritis  and various infections. Infections may be  associated with collections of the fluid in the joint  cavity. This gives rise to swelling above, and at the  sides of the patella. The patella appears to float in  the fluid. Aspiration of fluid can be done by passing  a needle into the joint on either side of the patella.  Bursae around the joint may get filled with fluid  resulting in swellings.   a. Injuries to menisci strains in a slightly flexed  knee, as in kicking a football, the meniscus may  get separated from the capsule, or may be torn  longitudinally (bucket-handle tear) or  transversely (see Fig. 2.18).   The medial meniscus is more vulnerable to  injury than the lateral because of its fixity to the  tibial collateral ligament, and because of greater  excursion during rotatory movements. The  lateral meniscus is protected by the popliteus  which pulls it backwards so that it is not crushed  between the articular surfaces.   b. Injuries to cruciate ligaments are also common.  The anterior cruciate ligament is more  commonly damaged than the posterior. It may  be injured in violent hyperextension of the knee  or in anterior dislocation of the tibia. The  posterior ligament is injured in posterior  dislocation of the tibia. The injury may vary  from simple sprain to complete tear. Tear of the  ligaments leads to abnormal anteroposterior  mobility (Figs 12.15a and b).   c. Injuries to collateral ligaments are less common,  and may be produced by severe abduction and  adduction strains (Figs 12.16a and b).   • Mal-alignment of patella: Ideally the patella is resting  in the centre of the width of the femur in a relaxed  standing position. However, the patella position  may be altered congenitally or due to tightness of  surrounding structures which may lead to painful  conditions of the patello-femoral joint.   • Semimembranosus bursitis is quite common. It  causes a swelling in the popliteal fossa region on  the posteromedial aspect ( see Fig. 7.5).   • Baker's cyst is a central swelling, occurs due to  osteoarthritis of knee joint. The synovial membrane  protrudes through a hole in the posterior part of  capsule of knee joint.   • Hip joint and knee joint may need to be replaced  if beyond repair.   • In knee joint disease vastus medialis is first to  atrophy and last to recover ( see Fig. 3.27).   Figs 12.16a and b: Injury of: (a) Medial, and (b) lateral  collateral ligaments   Figs 12.15a and b: Rupture of: (a) Anterior, and (b) posterior  cruciate ligaments   Define the margins of both extensor retinacula, one  flexor retinaculum and both peroneal retinacula. Identify  the tendons enclosed in synovial sheaths, nerves and  blood vessels passing under them. Displace these  structures without removing them.   Clean and define the strong medial and lateral  ligaments of ankle joint. Also demarcate the thin anterior  and posterior parts of the capsule of the joint.   1 The lower end of the tibia including the medial  malleolus.   The inferior articular surface is formed by articular  areas on the upper, medial and lateral aspects of the  talus.   Structurally, the joint is very strong. The stability of  the joint is ensured by:   c. The tendons that cross the joint, four in front, and  three on posteromedial side and two on  posterolateral side (Fig. 12.17).   a. The downward projection of medial and lateral  malleoli, on the corresponding sides of talus.   b. By the inferior transverse tibiofibular ligament  that bridges across the gap between the tibia and  the fibula behind the talus (Fig. 12.18). The socket  is provided flexibility by strong tibiofibular  ligaments and by slight movements of the fibula  at the superior tibiofibular joint.   There are two factors, however, that tend to displace  the tibia and fibula forwards over the talus. These  factors are:   a. The forward pull of tendons which pass from the  leg to the foot.   b. The pull of gravity when the heel is raised.  Displacement is prevented by the following  factors.   i. The talus is wedge-shaped, being wider  anteriorly. The malleoli are oriented to fit this  wedge.    ii. The posterior border of the lower end of the  tibia is prolonged downwards.   iv. The tibiocalcanean, posterior tibiotalar,  calcaneofibular and posterior talofibular  ligaments pass backwards and resist forward  movement of the tibia and fibula.   It surrounds the joint but is weak anteriorly and  posteriorly. It is attached all around the articular  margins with two exceptions.   1 Posterosuperiorly, it is attached to the inferior  transverse tibiofibular ligament.   2 Anteroinferiorly, it is attached to the dorsum of the  neck of the talus at some distance from the trochlear  surface.   The anterior and posterior parts of the capsule are  loose and thin to allow hinge movements. On each side,  however, it is supported by strong collateral ligaments.   The synovial membrane lines the capsule. The joint  cavity ascends for some distance between the tibia and  the fibula.   This is a very strong triangular ligament present on  the medial side of the ankle. The ligament is divided    Fig. 12.17: Anterior view of coronal section through the right ankle joint to show its relations    Fig. 12.19: Medial side of the ankle joint showing the parts of  deltoid ligament    into a superficial and a deep part. Both parts have a  common attachment above to the apex and margins  of the medial malleolus. The lower attachment is  indicated by the name of the fibres (Fig. 12.19).   1 Anterior fibres or tibionavicular are attached to the  tuberosity of the navicular bone and to the medial  margin of the spring ligament.   2 The middle fibres or tibiocalcanean are attached to the  whole length of the sustentaculum tali.   3 The posterior fibres or posterior tibiotalar are attached  to the medial tubercle and to the adjoining part of  the medial surface of the talus.   Deep part or anterior tibiotalar is attached to the  anterior part of the medial surface of the talus.   The deltoid ligament is crossed by the tendons of  the tibialis posterior and flexor digitorum longus.   The deltoid ligament is a very strong ligament and  excessive tensile forces on the ligament result in an  avulsion fracture rather than a tear of the ligament. The  ligament is prone to injuries in inversion.   1 The anterior talofibular ligament is a flat band which  passes from the anterior margin of the lateral  malleolus to the neck of the talus, just in front of the  fibular facet (Fig. 12.20).    Fig. 12.20: Lateral side of the ankle joint showing the lateral  ligament    2 The posterior talofibular ligament passes from the lower  part of the malleolar fossa of the fibula to the lateral  tubercle of the talus.   3 The calcaneofibular ligament is a long rounded cord  which passes from the notch on the lower border of  the lateral malleolus to the tubercle on the lateral  surface of the calcaneum. It is crossed by the tendons  of the peroneus longus and brevis.   4 The interosseous tibiofibular ligament, inferior  extensor retinaculum and inferior and superior  peroneal retinacula also contribute to the stability of  the ankle joint (see Figs 8.4 and 8.9).   Anteriorly , from medial to lateral side, there are the  tibialis anterior, the extensor hallucis longus, the  anterior tibial vessels, the deep peroneal nerve, the  extensor digitorum longus, and the peroneus tertius  (Fig. 12.17).   Posteromedially , from medial to lateral side, there are  the tibialis posterior, the flexor digitorum longus, the  posterior tibial vessels, the tibial nerve, the flexor  hallucis longus.   1 In dorsiflexion the forefoot is raised, and the angle  between the front of the leg and the dorsum of the  foot is diminished. It is a close-pack position with  maximum congruence of the joint surfaces. The  wider anterior trochlear surface of the talus fits into  lower end of narrow posterior part of the lower end  of tibia. There are no chances of dislocation in  dorsiflexion (see Fig. 11.13).   2 In plantar flexion , the forefoot is depressed, and the  angle between the leg and the foot is increased. The  narrow posterior part of trochlear surface of talus  loosely fits into the wide anterior part of the lower  end of tibia. High heels cause plantar flexion of ankle  joint and its dislocations (see Fig. 9.10).    • The sprains of the ankle are almost always abduction  sprains of the subtalar joints, although a few fibres  of the deltoid ligament are also torn. True sprains  of the ankle joint are caused by forced plantar  flexion, which leads to tearing of the anterior fibres  of the capsule. The joint is unstable during plantar  flexion.   • Dislocations of the ankle are rare because joint is very  stable due to the presence of deep tibiofibular  socket. Whenever dislocation occurs, it is  accompanied by fracture of one of the malleoli.   ■ Acute sprains of lateral ankle occur when the foot  is plantar flexed and excessively inverted. The  lateral ligaments of ankle joint are torn giving rise  to pain and swelling.   • Acute sprains of medial ankle occur in excessive  eversion, leading to tear of strong deltoid  ligament. These cases are less common.   • The optimal position of the ankle to avoid ankylosis  is one of slight plantar flexion.   • For injections into the ankle joint, the needle is  introduced between tendons of extensor hallucis  longus and tibialis anterior with the ankle partially  plantar flexed.   • During walking, the plantar flexors raise the heel  from the ground. When the limb is moved  forwards the dorsiflexors help the foot in clearing  the ground. The value of the ankle joint resides in  this hinge action, in this to and fro movement of  the joint during walking.   Superior tibiofibular joint: Remove the muscles around  the superior tibiofibular joint. Define the tendon of  popliteus muscle on its posterior surface. Open the joint.   Middle tibiofibular joint: Remove the muscles from  anterior and posterior surface of the interosseous  membrane and define its surfaces.   Inferior tibiofibular joint: Define the attachments of  anterior and posterior tibiofibular ligaments including  inferior transverse tibiofibular ligament. Divide these to  expose the strong interosseous tibiofibular ligament.  Use dry bones and articulated foot to understand the  attachments of the ligaments.   The tibia and fibula articulate at three joints, the  superior, middle and inferior tibiofibular joints.   This is a small synovial joint of the plane variety. It is  formed by articulation of small, rounded, flat facets  present on the head of the fibula, and on the lateral  condyle of the tibia. The joint permits slight gliding or  rotatory movements that help in adjustment of the  lateral malleolus during movements at the ankle joint.   The bones are united by a fibrous capsule which is  strengthened by anterior and posterior ligaments. These  ligaments are directed forwards and laterally. The  cavity of the joint may communicate with the knee joint  through the popliteal bursa. The joint is supplied by  the nerve to the popliteus, and by the recurrent  genicular nerve (see Fig. 6.7).   This is a fibrous joint formed by the interosseous  membrane connecting the shafts of the tibia and the  fibula. The interosseous membrane is attached to the  interosseous borders of the two bones. Its fibres are  directed downwards and laterally. It is wide above and  narrow below where it is continuous with the  interosseous ligament of the inferior tibiofibular joint.  It presents a large opening at the upper end for the  passage of the anterior tibial vessels, and a much smaller  opening near its lower end for the passage of the  perforating branch of the peroneal artery (see Fig. 2.24).   Tibialis anterior, extensor digitorum longus, anterior  tibial vessels, deep peroneal nerve extensor hallucis  longus and peroneus tertius (see Fig. 8.5).   3 Resists the downward pull exerted on the fibula by  the powerful muscles attached to the bone. Note that  the biceps femoris is the only muscle that pulls the  fibula upwards.   This is a syndesmosis uniting the lower ends of the tibia  and the fibula (Fig. 12.18). The bony surfaces are  connected by a very strong interosseous ligament, which  forms the chief bond of union between the lower ends  of these bones.   The interosseous ligament is concealed both in front  and behind by the anterior and posterior tibiofibular  ligaments , whose fibres are directed downwards and  laterally.   The posterior tibiofibular ligament is stronger than  the anterior. Its lower and deep portion forms the  inferior transverse tibiofibular ligament , which is a strong  thick band of yellowish fibres passing transversely from  the upper part of the malleolar fossa of the fibula to the  posterior border of the articular surface of the tibia,  reaching up to the medial malleolus (Fig. 12.18).   Perforating branch of the peroneal artery; and the  malleolar branches of the anterior and posterior tibial  arteries (see Fig. 9.7).   The joint permits slight movements, so that the lateral  malleolus can rotate laterally during dorsiflexion of the  ankle.    • The inferior tibiofibular joint is strong. The  strength of the ligaments uniting the lower ends  of the tibia and fibula is an important factor in  maintaining the integrity of the ankle joint.   • The slight movements of the lateral malleolus  taking place at this joint provide suppleness to the  ankle joint.   Remove all the tendons, muscles from both dorsal and  plantar aspects of the tarsal, metatarsal and phalanges.  Define, identify the ligaments joining the various bones.  Ligaments are stronger on the plantar aspect than the  dorsal aspect.   Divide the ligaments which unite the talus and calcaneus  together at the talocalcanean, talocalcaneonavicular  joints. Study these joints carefully to understand the  movements of inversion and eversion.   On the lateral side of foot, define the attachments of  long plantar ligament. Reflect this ligament from its  proximal attachment to see the deeper plantar calcaneo¬  cuboid ligament.   The joints of the foot are numerous. They can be classified  as:   The main intertarsal joints are the subtalar or  talocalcanean joint, the talocalcaneonavicular joint and  the calcaneocuboid joint. Smaller intertarsal joints  include the cuneonavicular, cuboidonavicular,  intercuneiform and cuneocuboid joints.   a. The intertarsal, tarsometatarsal and intermetatarsal  joints permit gliding and rotatory movements.   which jointly bring about inversion, eversion, of  the foot. Pronation is a component of eversion,  while supination is a component of inversion.   b. The metatarsophalangeal joints permit flexion,  extension, adduction and abduction of the toes.   c. The interphalangeal joints of hinge variety permit  flexion and extension of the distal phalanges.   There are three joints, posterior, anterior and medial  between the talus and the calcaneum. The posterior joint  is named the talocalcanean or subtalar joint where  concave undersurface of body of talus articulates with  convex posterior facet of the calcaneum.   The anterior joints are parts of the talocalcaneo¬  navicular joint. On the anterior and medial side of  undersurface of head of talus, the surfaces are convex  and articulate with concave articulating surfaces of  calcaneum.   Since the three joints form a single functional unit,  clinicians often include these joints under the term  subtalar joint. However, the sinus tarsi separates the  posterior articulations from the anterior and medial  articulations. The greater part of the talocalcaneo¬  navicular joint lies in front of the head of the talus and  not below it (Figs 12.22a and b).    Figs 12.22a and b: Axis of movements of inversion and eversion  at subtalar joint: (a) Side view, and (b) superior view   The talocalcanean joint is a plane synovial joint between  the concave facet on the inferior surface of the body of  the talus and the convex facet on the middle one-third  of the superior surface of the calcaneum.   The interosseous talocalcanean ligament is thick and  very strong. It is the chief bond of union between  the talus and the calcaneum. It occupies the sinus  tarsi, and separates the talocalcanean joint from the  talocalcaneonavicular joint. It becomes taut in  eversion, and limits this movement.   The cervical ligament is placed lateral to the sinus  tarsi. It passes upwards and medially, and is attached  above to a tubercle on the inferolateral aspect of the  neck of the talus. It becomes taut in inversion, and  limits this movement.   In addition to the interosseous and cervical  ligament, the collateral ligaments of the ankle joint  also provide stability to the talocalcanean joint.   The joint participates in the movements of inversion  and eversion of the foot described at the end of chapter.   The joint has some of the features of a ball and socket  joint. The head of the talus fits into a socket formed  partly by the navicular bone, and partly by the  calcaneum. Two ligaments also take part in forming  the socket: these are the spring ligament medially, and  the medial limb of the bifurcate ligament laterally  (Figs 12.22a and b).   The bones taking part in forming the joint are  connected by a fibrous capsule. The capsule is  supported posteriorly by the interosseous talocalcanean  ligament; dorsally by the dorsal talonavicular ligament;  ventromedially by the spring ligament; and laterally  by the medial limb of the bifurcate ligament. The spring  ligament is described below. The bifurcate ligament is  described with the calcaneocuboid joint.   The movements permitted at this joint are those of  inversion and eversion. They are described below.   The spring ligament or plantar calcaneonavicular  ligament is powerful. It is attached posteriorly to the  anterior margin of the sustentaculum tali, and  anteriorly to the plantar surface of the navicular bone  between its tuberosity and articular margin. The head  of the talus rests directly on the upper surface of the  ligament, which is covered by fibrocartilage. The  plantar surface of the ligament is supported by the  tendon of tibialis posterior medially, and by the tendons  of flexor hallucis longus and flexor digitorum longus,  laterally.   The spring ligament is the most important ligament  for maintaining the medial longitudinal arch of the foot.    It is attached posteriorly to the plantar surface of the  calcaneum, and anteriorly to the lips of the groove on  the cuboid bone, and to the bases of the middle three  metatarsals. It converts the groove on the plantar  surface of the cuboid into a tunnel for the tendon of  the peroneus longus. Morphologically, it represents  the divorced tendon of the gastrocnemius.   The short plantar ligament or plantar calcaneocuboid  ligament lies deep to the long plantar ligament. It is  broad and strong ligament extending from the anterior  tubercle of the calcaneum to the plantar surface of the  cuboid, behind its ridge.   This is a saddle joint. The opposed articular surfaces of  the calcaneum and the cuboid are concavoconvex. On  account of the shape of articular surfaces, medial  movement of the forefoot is accompanied by its lateral  rotation and adduction or inversion. Lateral movement  of the forefoot is accompanied by medial rotation and  abduction or eversion. The bones are connected by:   The bifurcate ligament is Y-shaped. Its stem is attached  to the anterolateral part of the sulcus calcanei; the  medial limb or calcaneonavicular ligament, to the  dorsolateral surface of the navicular bone; and the  lateral limb or calcaneocuboid ligament, to the  dorsomedial surface of the cuboid bone. Thus each limb  of the ligament strengthens a separate joint.   The long plantar ligament (Fig. 12.23) is a long and  strong ligament whose importance in maintaining the  arches of foot is surpassed only by the spring ligament.    Fig. 12.23: Some ligaments of the foot with the tendons of  peroneus longus    This includes the calcaneocuboid and the talonavicular  joints (Fig. 12.21). The talonavicular joint is a part of the  talocalcaneonavicular joint, and hence the transverse  tarsal joint may be said to be made up of only one and a  half joints. These joints are grouped together only by  virtue of being placed in nearly the same transverse  plane. In any case, the two joints do not form a  functional unit. They have different axes of movements.  It demarcates the forefoot from the hindfoot. Its  movements help in inversion and eversion of the foot.   Inversion is a movement in which the medial border  of the foot is elevated, so that the sole faces medially.   Eversion is a movement in which the lateral border  of the foot is elevated, so that the sole faces laterally.  These movements can be performed voluntarily only  when the foot is off the ground. When the foot is on the  ground these movements help to adjust the foot to  uneven ground.   In inversion and eversion, the entire part of the foot  below the talus moves together. The movement takes  place mainly at the subtalar and talocalca¬  neonavicular joints and partly at the transverse tarsal  joint. The calcaneum and the navicular bone, move  medially or laterally round the talus carrying the  forefoot with them. Inversion is accompanied by plantar  flexion of the foot and adduction of the forefoot.  Eversion is accompanied by dorsiflexion of the foot and  abduction of the forefoot.   Inversion and eversion take place around an oblique  axis which runs forwards, upwards and medially,  passing from the back of the calcaneum, through the  sinus tarsi, to emerge at the superomedial aspect of the  neck of the talus. The obliquity of the axis partly  accounts for adduction, abduction, plantar flexion and  dorsiflexion which are associated with these  movements (Fig. 12.22).   2 The range of movements is appreciably increased in  plantar flexion of the foot because, in this position,  the narrow posterior part of the trochlear surface of  the talus occupies the tibiofibular socket. In this  position slight side to side movements of the talus  are permitted.   Inversion is produced by the actions of the tibialis  anterior and the tibialis posterior, helped by the flexor  hallucis longus and the flexor digitorum longus  (Table 12.4).   Mechanism: During inversion the forepart of foot is  adducted at mid tarsal joint followed by lateral rotation  of foot at subtalar jont. During eversion the reverse of  this occurs.   These are really components of the movements of  inversion and eversion. In pronation and supination,  the forefoot (i.e. the distal part of the tarsus and  metatarsus) moves on the calcaneum and talus. The  medial border or the forefoot is elevated in supination  (which is thus a part of inversion), while the reverse  occurs in pronation (and the eversion). These  movements take place chiefly at the transverse tarsal  joint and partly at smaller intertarsal, tarsometatarsal  and intermetatarsal joints.   There are differences when supination and pronation  occur in weight bearing and nonweight bearing  situations. In weight bearing supination and pronation,  the calcaneum is not free to move in all directions and    the motions are thus completed by compensatory  movements of the talus.   Inversion and eversion greatly help the foot in adjusting  to uneven and slippery ground. When feet are  supporting the body weight, these movements occur  in a modified form called supination and pronation,  which are forced on the foot by the body weight.   Cut across the cuneocuboid, cuneonavicular and  intercuneiform joints to expose the articulating surfaces.   With a strong knife cut through tarsometatarsal and  intermetatarsal joints. Try to separate the bones to see  interosseous ligaments.   Detach abductor hallucis, flexor hallucis brevis,  adductor hallucis from the sesamoid bones of the big  toe.   Cut the deep transverse metatarsal ligaments on  each side of the third toe. Now the tendons of dorsal  and plantar interossei can be seen till their insertion.  Identify the distal attachments of the lumbrical muscles  as well.   Identify the extensor expansion on the dorsum of  digits and see its continuity with the collateral ligaments.  Study these joints from the text provided.   These are plane joints between the navicular, the  cuneiform, the cuboid and the metatarsal bones. They  permit small gliding movements, which allow elevation  and depression of the heads of the metatarsals, as well  as pronation and supination of the foot.   There are only six joint cavities in the proximal part of  the foot. These are intertarsal, tarsometatarsal and  intermetatarsal joints (Fig. 12.24). The cavities are:   Medial cuneiform  Intermediate cuneiform  1 st cuneometatarsal joint (4)  First metatarsal    Fig. 12.24: Joint cavities in the proximal part of the foot   6 Cuneonavicular with extensions (Fig. 12.21), i.e.  navicular with three cuneiforms and second and  third cuneometatarsal joints.   1 The deep transverse ligaments of the foot connect  all the five toes instead of only four fingers in the  hand.   2 The toes are adducted and abducted with reference  to the second toe and not the third finger as in the  hand.    Gait is a motion which carries the body forwards. There  are two phases: Swing and stance (Figs 12.25a to d).   1 Flexion of hip, flexion of knee and plantar flexion of  ankle.   2 Flexion of hip, extension of knee and dorsiflexion of  ankle.   1 Flexion of hip, extension of knee and foot on the  ground.   2 Extension of hip, extension of knee and foot on the  ground.    • Females wearing high heels (more than 5 cm), put  stress on their back and lower limbs. The spine is  pushed forwards, knees are excessively bent,  resulting in too much pull on some muscles and  ligaments. High heels result in shift in position of  centre of gravity. The problems caused by high  heels are "fashionable diseases". The sprains of  the medial and lateral ligaments of ankle joint are  almost always due to high heels (see Fig. 9.10).   • Joints of the foot lead to various deformities like  mallet toe, hammer toe and claw toe (Fig. 12.26).   • Arthroscopy: One can look into the joints by special  instruments called the arthroscopes.   For hip joint, the instrument is introduced 4 cm  lateral to the femoral pulse and 4 cm below  inguinal ligament.   For knee joint, the arthroscope is introduced from  the front of the semiflexed knee joint.   Phases of gait: (a) and (b) Swing phase, (c) and (d) stance phase    For ankle joint, the instrument is introduced medial  to the tendon of tibialis anterior muscle. One needs  to be careful of the great saphenous vein.   • Hallux valgus: Due to ill-fitting shoes great toe gets  pushed laterally, even dislocating the sesamoid  bone. Head of 1st metatarsal points medially and  adventitious bursa develops there. Toes may be  deformed at their joints resulting in claw toe.   • Fractured toe is bandaged with the adjacent toe,  this is called buddy splint (Fig. 12.27).   In intrauterine life and early infancy, the soles of the  feet are turned inwards, so that they face each others.  As growth proceeds, the feet are gradually everted to  allow a plantigrade posture. Such eversion does not  occur in apes.   Locking is medial rotation of femur on tibia at  terminal stages of extension when foot is on the  ground.   Unlocking is lateral rotation of femur on tibia at initial  stages of flexion when foot in on the ground.   Locking is lateral rotation of tibia on femur at terminal  stages of extension when foot in off the ground.   Unlocking is medial rotation of tibia on femur at  initial stages of flexion when foot is off the ground.   • Flexion and extension are allowed in the upper  compartment of knee joint while rotation is  permitted in the lower or meniscotibial  compartment.   • Inversion and eversion occur at talocalcaneo¬  navicular joint, assisted by movements at  transverse tarsal joints, i.e. talonavicular and  calcaneocuboid joints.   • Tendon of peroneus longus crosses the sole from  lateral to medial side   • Inferior tibiofibular joint is a syndesmosis type of  joint, i.e. joint formed by ligaments only.   • Fibula does not take part in knee joint, but  participates in the formation of ankle joint.   • Talus has no muscular attachment. Tendon of  flexor hallucis longus courses between the two  tubercles of its posterior process   • The big toe carries double the weight to the ground  than any of other four toes.   The knee of a football player was flexed at right  angle. At this time, his knee was so injured that his  tibia got driven forwards.   • What are its attachments? What other ligaments  can be injured?   Ans: The injured ligament is anterior cruciate  ligament. It is attached below to anterior part of  intercondylar area of tibia. It is attached above to  the medial surface of a lateral condyle of femur. This  ligament binds the two bones together. With this  injury, the menisci and fibular collateral ligaments  may also be torn.   A sportsman, while playing basketball sprained his  ankle. He complained of severe pain on the lateral  side of his right ankle.   Ans: The sportsman's anterior talofibular ligament  is torn. The posterior talofibular and calcaneofibular  ligaments could also be torn. The lower end of fibula  could also be fractured.    1. All of the following muscles extend thigh at hip  joints except:   2. Strongest ligament around hip joint which prevents  overextension during standing?   3. At beginning of flexion of locked knee, the joint is  unlocked by which of following muscle?   a. It is a hinge joint made up of articulations between  femur, tibia and fibula   b. The tendon of popliteus perforates capsule  posteriorly and attached to medial meniscus    c. It contains two semilunar cartilages, medial one  being longer and more liable to injury   d. The anterior cruciate ligament arises from  anterior intercondylar area in front of anterior  end of medial semilunar cartilage   d. The tone of muscle acting on joint, especially  quadriceps femoris   c. It is formed by distal ends of tibia and fibula  articulating with body of talus   8. All of following muscles are concerned with  dorsiflexion of foot at ankle joint except:    9. All muscles are invertors of foot at talocalcaneo¬  navicular joint except:  a. Tibialis posterior b. Peroneus tertius  c. Tibialis anterior d. Flexor digitorum longus   10. Abduction and adduction of forefoot takes place at  which of following joints?  a. Ankle joint b. Tarsometatarsal joints   Arches of the foot help in fast walking, running and  jumping. In addition, these help in weight-bearing and  in providing upright posture. The foot is really unique  to human being. Arches are supported by intrinsic and  extrinsic muscles of the sole in addition to ligaments,  aponeurosis and shape of the bones. Foot prints are not  complete due to the arches. The foot has to suffer from  many disorders because of tight shoes or high heels  which one wears for various reasons.   1 As a pliable platform to support the body weight in  the upright posture, and   2 As a lever to propel the body forwards in walking,  running or jumping.   To meet these requirements, the human foot is  designed in the form of elastic arches or springs. These  arches are segmented, so that they can best sustain the  stresses of weight and of thrusts. The presence of the  arches makes the sole concave. This is best appreciated  by examining foot prints which show the weight¬  bearing parts of the sole (Fig. 13.1).   An arched foot is a distinctive feature of man. It  distinguishes him from other primates. The arches are  present right from birth, although they are masked in  infants by the excessive amount of fat in their soles.    Fig. 13.1: Foot print showing the weight-bearing points of the  sole   This arch is considerably higher, more mobile and  resilient than the lateral. It is considered as a big arc of  a small circle. Its constitution is as follows:   The anterior end is formed by the heads of the first,  second and third metatarsals. The phalanges do not take  part in forming the arches. The posterior end of this arch  is formed by the medial tubercle of the calcaneum  (Fig. 13.2).   The summit of the arch is formed by the superior  articular surface of the body of the talus.   Fig. 13.2: Bones forming the medial longitudinal arch of foot:  Superior view   The anterior pillar is long and weak. It is formed by the  talus, the navicular, the three cuneiform bones, and the  first three metatarsal bones. The posterior pillar is short  and strong. It is formed by the medial part of the  calcaneum (Fig. 13.3).   This arch is characteristically low, has limited mobility,  and is built to transmit weight and thrust to the ground.  It is considered as a small arc of a big circle. This is in  contrast to the medial longitudinal arch which acts as   Fig. 13.3: Bones forming the medial longitudinal arch of foot:  Medial view   a shock absorber. The constitution of the lateral  longitudinal arch is as follows.   The anterior end of the arch is formed by the heads of the  4th and 5th metatarsal bones. The posterior end is formed  by the lateral tubercle of the calcaneum (Fig. 13.4).   Fig. 13.4: Bones forming the lateral longitudinal arch of foot:  Lateral view   The summit lies at the level of the articular facets on the  superior surface of the calcaneum at the level of the  subtalar joint.   The anterior pillar is long and weak. It is formed by the  cuboid bone and by the 4th and 5th metatarsals. The  posterior pillar is short and strong. It is formed by the  lateral half of the calcaneum.   The anterior transverse arch is formed by the heads of  the five metatarsal bones. It is complete because the  heads of the first and fifth metatarsals both come in  contact with the ground, and form the two ends of the  arch.   The posterior transverse arch is formed by the greater  parts of the tarsus and metatarsus. It is incomplete  because only the lateral end comes in contact with the  ground, the arch forming a 'half dome' which is  completed by a similar half dome of the opposite foot.   In general, the factors helping in maintaining the  various arches are as follows:   2 Intersegmental ties/staples or ligaments (and muscles)  that hold the different segments of the arch together.   3 Tie beams or bowstrings that connect the two ends of  the arch.   4 Slings that keep the summit of the arch pulled up.  Each of these factors is considered below.   The posterior transverse arch is formed, and maintained  mainly because of the fact that many of the tarsal bones  involved (e.g. the cuneiform bones), and the heads of  the metatarsal bones, are wedge-shaped, the apex of  the wedge pointing downwards.   The bony factor is not very important in the case of  the other arches.   All arches are supported by the ligaments uniting the  bones concerned. The most important of these are as  follows:   1 The spring ligament for the medial longitudinal arch  (Fig. 13.5).   2 The long and short plantar ligaments for the lateral  longitudinal arch (see Fig. 12.23).   3 In the case of the transverse arch, the metatarsal  bones are held together by the interosseous muscles  also.    Fig. 13.5: Scheme showing some factors maintaining the medial  longitudinal arch of the foot   The longitudinal arches are prevented from flattening  by the plantar aponeurosis, and by the muscles of the  first layer of the sole. These structures keep the anterior  and posterior ends of these arches pulled together. In  the case of the transverse arch, the adductor hallucis  acts as a tie beam (see Figs 10.4a and 10.6a).   1 The summit of the medial longitudinal arch is pulled  upwards by tendons passing from the posterior   compartment of the leg into the sole, i.e. tibialis  posterior, flexor hallucis longus, flexor digitorum  longus (Fig. 13.7).   2 The summit of the lateral longitudinal arch is pulled  upwards by the peroneus longus and peroneus  brevis (Fig. 13.6).   3 The tendons of tibialis anterior and peroneus longus  together form a sling (stirrup) which keeps the  middle of the foot pulled upwards, thus supporting  the longitudinal arches.   4 As the tendon of the peroneus longus runs  transversely across the sole, it pulls the medial and  lateral margins of the sole closer together, thus  maintaining the transverse arches. The transverse  arch is also supported by tibialis posterior which  grips many of the bones of the sole through its slips  (Fig. 13.7).   1 The arches of the foot distribute body weight to the  weight-bearing areas of the sole, mainly the heel and  the toes. Out of the latter, weight is borne mainly on  the first and fifth toes. The lateral border of the foot  bears some weight, but this is reduced due to the  presence of the lateral longitudinal arch.   2 The arches act as springs (chiefly the medial  longitudinal arch) which are of great help in walking  and running.   3 They also act as shock absorbers in stepping and  particularly in jumping.   4 The concavity of the arches protects the soft tissues  of the sole against pressure.   5 The character of medial longitudinal arch is resiliency  and that of lateral longitudinal arch is rigidity.    Fig, 13,7: Insertion of the tibialis posterior. Note the slips passing  to all tarsal bones (except the talus) and to the middle three  metatarsals   The arches of the foot are well known features of the foot.  There are two longitudinal arches, i.e. medial longitudinal  arch and lateral longitudinal arch (Table 13.1).   In addition there are two transverse arches, i.e.  posterior transverse arch and an anterior transverse  arch (Table 13.2).    The medial longitudinal arch is the most important and  is primarily affected in pes planus and pes cavus.   This arch is formed by the calcaneus, navicular, three  cuneiforms and medial three metatarsals.   • Abductor hallucis and flexor digitorum brevis  which act as spring ties.   • Tibialis anterior which lifts the centre of the arch.  This muscle also forms a stirrup like support with  the help of peroneus longus muscle.   • Tibialis posterior adducts the mid-tarsal joint and  supports the spring ligament.   • Flexor hallucis longus extending between the  anterior and posterior ends also supports the head  of talus.   The lateral longitudinal arch is formed by  calcaneum, cuboid, 4th and 5th metatarsals. It is  rather shallow and gets flattened on weight  bearing.   • This arch is supported by long plantar ligament,  short plantar ligament. Plantar aponeurosis acts  as a tie beam.   • Flexor digitorum brevis, flexor digiti minimi and  abductor digiti minimi act as tie beams.   • Peroneus longus, peroneus brevis and peroneus  tertius support this arch.    Table 13-1: Comparison of medial longitudinal arch and lateral longitudinal arch   Articular facet on superior surface of calcaneum  at level of subtalar joint   Table 13.2: Comparison of anterior transverse arch and posterior transverse arch    Anterior transverse arch  Heads of 1st to 5th metatarsals  Complete arch  Round-shaped  Dorsal interosseous muscles  Adductor hallucis   Navicular, 3 cuneiforms, bases and shafts of metatarsals  Incomplete. Arch is half dome raised medially  Wedge-shaped  Dorsal interosseous muscles    Posterior transverse arch is formed by three cuneiforms  and cuboid. This arch extends across the sole in a  coronal plane. It is only a half arch, the other half gets  completed by the other foot. This arch is supported by  the ligaments binding the bones. It gets specific support  from the tendon of peroneus longus as it extends from  the lateral side to the medial side of the sole   Anterior transverse arch also lies in coronal plane. It  is formed by the heads of five metatarsals. During  weight bearing, the metatarsal heads flatten out.   This arch is supported by intermetatarsal ligaments  and the intrinsic muscles of the sole. The transverse  head of adductor hallucis holds the heads of metatarsals  together ( see Fig. 10.6a).    * Absence or collapse of the arches leads to flat  foot (pes planus), which may be congenital or  acquired. The effects of a flat foot are as follows.   a. Loss of spring in the foot leads to a clumsy,  shuffling gait.   b. Loss of shock absorbing function makes the foot  more liable to trauma and osteoarthritis.   c. Loss of the concavity of the sole leads to  compression of the nerves and vessels of the sole.  Compression of the communication between  the lateral and medial plantar nerves causes  neuralgic pain in the forefoot (metatarsalgia).  Compression of blood vessels may cause  vascular disturbances in the toes.   • Exaggeration of the longitudinal arches of the  foot is known as pes cavus. This is usually a result  of contracture (plantar flexion) at the transverse  tarsal joint. When dorsiflexion of the metatarso¬  phalangeal joints, and plantar flexion of the  interphalangeal joints (due to atrophy of  lumbricals and interossei) are superadded, the  condition is known as claw-foot. The common  causes of pes cavus and claw-foot are spina bifida  and poliomyelitis (Figs 13.8a to d and 13.9).   a. Talipes equinus in which the patient walks on  toes, with the heel raised.   b. Talipes calcaneus in which the patient walks on  heel, with the forefoot raised.   c. Talipes varus in which the patient walks on the  outer border of foot which is inverted and  adducted (see Fig. 10.13).   d. Talipes valgus in which the patient walks on inner  border of foot which is everted and abducted.   e. Commonest deformity of the foot is talipes  equinovarus (clubfoot). In this condition the foot  is inverted, adducted and plantar flexed. The  condition may be associated with spina bifida.   * Talipes (club foot) may be of two types: Talipes  calcaneovalgus—foot is dorsiflexed at ankle joint,  everted at midtarsal joints.   ■ Talipes equinovarus—foot is plantar flexed at ankle  joint and inverted at midtarsal joints (Fig. 13.10).   Figs 13.8a to d: (a), (b) Flat feet, (c) pes cavus, and (d) normal    • Talus is the summit of medial longitudinal arch of  the foot.   • Main supports of this arch are tibialis posterior,  tibialis anterior and peroneus longus muscles   • Important ligaments of the arch are spring or  plantar calcaneonavicular, interosseous talocal-  canean   • Great toe through its two sesamoid bones transfers  double the weight of the other toes.   • Important joint of lateral longitudinal arch is  calcaneocuboid joint. Its main supports are tendon  of peroneus longus, long plantar and short plantar  ligaments.   • Posterior transverse arch is supported by tendon  of peroneus longus muscle.   • Anterior transverse arch is supported by deep  metatarsal ligaments and dorsal interossei muscles.    A young adult was disqualified in his medical  examination of the army due to his flat feet   • Name the factors maintaining the medial  longitudinal arch of the foot   Ans: When the feet do not show the upward  concavity along the medial border of foot, the foot is  called "flat foot". If such a person puts his wet feet  on the ground, there will be impression of the whole  foot. Flat foot persons cannot rim as fast as arched  foot persons. The in army persons are required to  run fast, so a flat foot person may be disqualified.   3. Short muscles like abductor hallucis, flexor  hallucis brevis, dorsal interossei   4. Long tendons like flexor hallucis longus, tibialis  posterior, peroneus longus, tibialis anterior.   2. Which does not take part in formation of medial  longitudinal arch of foot?   3. The major ligament that supports head of talus from  below, as it articulates with navicular bone is:   a. Tibialis posterior b. Flexor hallucis longus  c. Peroneus brevis d. Flexor digitorum longus   a. Peroneus longus b. Peroneus brevis  c. Peroneus tertius d. Extensor digitorum brevis   It corresponds to the upper two-thirds of a line joining  the following two points.   • Midinguinal point: A point midway between the  anterior superior iliac spine and the pubic symphysis  (Fig. 14.1).   • Adductor tubercle : It lies at the lower end of the cord¬  like tendon of the adductor magnus. The tendon can  be felt in a shallow groove just behind the  prominence of the vastus medialis when the thigh is  semiflexed, abducted and laterally rotated .   The upper one-third of the line represents the upper  half of the artery lying in the femoral triangle. The  middle one-third of the line represents the lower half    Fig. 14.1: Femoral vessels, profunda femoris artery, femoral  nerve, femoral ring and saphenous opening in the thigh    of the artery lying in the adductor canal. The lower one-  third of the line represents the descending genicular  and saphenous branches of the artery.   First mark the femoral artery. The profunda artery is  then marked by joining the following two points on  the femoral artery (Fig. 14.1).   • Second point: 10 cm below the midinguinal point.  The artery is slightly convex laterally in its upper   • First point: At the junction of the middle and lower  thirds of the thigh, 2.5 cm medial to the midline on  the back of the limb (Fig. 14.2).   • Second point: On the midline of the back of the knee.   • Third point: On the midline of the back of leg at the  level of the tibial tuberosity.   • Second point: At the apex of the greater trochanter  (Fig. 14.3).   The superior gluteal artery enters the gluteal region  at the junction of the upper and middle thirds of the  line joining points (1st) and (2nd).   Then mark a third point 2.5 cm lateral to the midpoint  of the line joining 1st and 2nd points. The sciatic nerve   • First point: 2.5 cm below the medial side of the head  of the fibula (Fig. 14.4).   • First point: On the midline of the back of the leg at  the level of the tibial tuberosity.   • Second point: Midway between the medial malleolus  and the tendocalcaneus (Fig. 14.2).   • Second point: At the proximal end of the first  intermetatarsal space (Fig. 14.4).   • First point: Midway between the medial malleolus  and the prominence of the heel.   • Second point: On the navicular bone which lies  midway between the back of the heel and the root of    Fig. 14.3: Surface marking of sciatic nerve gluteal arteries and Fig. 14.4: Surface marking of anterior tibial, dorsalis pedis  nerves arteries; deep and superficial peroneal nerves    Fig. 14.5: Surface marking of medial and lateral plantar nerves  and vessels, including the plantar arch    the big toe. The artery runs in the direction of the  first interdigital cleft (Fig. 14.5).   • First point: Midway between the medial malleolus  and the prominence of the heel.   • Second point: 2.5 cm medial to the tuberosity of the  fifth metatarsal bone (Fig. 14.5).   • First point: 2.5 cm medial to the tuberosity of the fifth  metatarsal bone.   • Second point: At the proximal end of the first  intermetatarsal space, 2.5 cm distal to the tuberosity  of the navicular bone (Fig. 14.5).   Its marking is same as that of the femoral artery, except  that the upper point is taken 1 cm medial to the  midinguinal point, and the lower point 1 cm lateral to  the adductor tubercle. The vein is medial to the artery  at the upper end, posterior to it in the middle, and  lateral to it at the lower end (Fig. 14.1).   It can be marked by joining the following points,  although it is easily visible in living subjects.   1 First point: On the dorsum of the foot at the medial  end of the dorsal venous arch.    2 Second point: On the anterior surface of the medial  malleolus.   3 Third point: On the medial border of the tibia at the  junction of the upper two-thirds and lower one-third  of the leg.   5 Fifth point: Just below the centre of the saphenous  opening (Fig. 14.6).    Popliteal vein formed  by venae comitantes  of posterior and  anterior tibial arteries    Fig. 14.6: Scheme to show the arrangement of the veins of the  lower limb (see text)   It can be marked by joining the following points,  although this vein is also easily visible in its lower part  (Fig. 14.7).   1 First point: On the dorsum of the foot at the lateral  end of the dorsal venous arch.   3 Third point: Just lateral to the tendocalcaneus above  the lateral malleolus.   • Second point: 2.5 cm vertically below the first point  (Fig. 14.1).   • First point: 2.5 cm lateral to the midpoint between  the posterior superior iliac spine and the ischial  tuberosity (Fig. 14.3).   • Second point: Just medial to the midpoint between the  ischial tuberosity and the greater trochanter.   • The third point: In the midline of the back of the thigh  at the junction of its upper two-thirds and lower one-  third, i.e. at the apex of the popliteal fossa.   • First point: In the midline of back of the thigh at the  junction of its upper two-thirds and lower one-third,  i.e. at the apex of the popliteal fossa.   • Second point: In the midline of back of the leg at the  level of tibial tuberosity (Fig. 14.7).   in the popliteal fossa, and the line joining (2) and (3)   • First point: At the apex of the popliteal fossa  (Fig. 14.8).   • Second point: On the back of the neck of the fibula  (see Fig. 7.7).   At the lower end the nerve turns forwards and ends  deep to the upper fibres of the peroneus longus.   • First point: On the lateral aspect of the neck of the  fibula (Fig. 14.4).   • Second point: In front of the ankle, midway between  the two malleoli.   The nerve lies lateral to the anterior tibial artery in  its upper and lower thirds, but anterior to the artery in  its middle-third.   • First point: On the lateral aspect of the neck of the  fibula (Fig. 14.4).   • Second point: On the anterior border of the peroneus  longus at the junction of the upper two-thirds and  lower one-third of the leg.   At the lower point the nerve pierces the deep fascia  and divides into medial and lateral branches.   It is marked in a manner similar to the medial plantar  artery (Fig. 14.5). Lies lateral to the artery.   It is marked in a manner similar to that for the lateral  plantar artery (Fig. 14.5). Lies medial to the artery.   1 The stem is about 1.5 cm broad. It extends from the  anterior part of the upper surface of the calcaneum  to a point medial to the tendon of the extensor  digitorum longus on the dorsum of the foot.   2 The upper band is about 1 cm wide, and extends from  the medial end of the stem to the anterior border of  the medial malleolus (Fig. 14.9).   3 The lower band is also about 1 cm wide. It extends  from the medial end of the stem to the medial side  of the foot, extending into the sole.   Its centre lies 4 cm below and 4 cm lateral to the pubic  tubercle. It is about 2.5 cm long and 2 cm broad,  with its long axis directed downwards and laterally  (Fig. 14.1).   It is represented by a horizontal line 1.25 cm long over  the inguinal ligament, 1.25 cm medial to the  midinguinal point (Fig. 14.1).   The retinaculum is about 3 cm broad vertically. It is  drawn from:   1 The anterior border of the triangular subcutaneous  area of the fibula.   2 The lower part of the anterior border of the tibia,  running medially and slightly upwards (Fig. 14.9).   2 The medial side of the heel, running downwards and  backwards (Fig. 14.10).    Fig. 14.0: Superior and inferior extensor retinacula of the ankle,  surface view    Fig. 14.10: Flexor retinaculum of the ankle, and the structures passing deep to it    In the study of plain skiagrams of the limbs, the  following points should be noted.   3 Normal relations of the bones forming joints and the  radiological 'joint space'.   Briefly, such skiagrams are helpful in the diagnosis  of the following.   2 Upper end of femur, including the head, neck, greater  trochanter, lesser trochanter, and upper part of shaft.  The neck-shaft angle is about 125 degrees in adults,  being more in children (140°) and less in females.   In the head, a dense wedge or triangle of cancellous  bone is known as Ward's triangle. It represents the  epiphyseal scar.   Calcar femorale is a dense plate of compact bone  forming a buttress to strengthen the concavity of the  neck-shaft angle in front of the lesser trochanter. It  transmits weight from the head of femur to the linea  aspera.   Cervical torus is a thickened band or ridge of  compact bone on the upper part of the neck between  the head and the greater trochanter.   1 Hip joint: Normal relation of the head of femur with  the acetabulum is indicated by the Shenton's line ,  which is a continuous curve formed by the upper  border of obturator foramen and the lower border  of the neck of femur (Fig. 14.11).   Note the epiphyses and other incomplete  ossifications if any, and determine the age.   The ischiopubic rami fuse by 7-8 years, and the  acetabulum is ossified by 17 years.   1 Lower end of femur, including the two condyles  (Figs 14.12 and 14.13).   2 Patella is clearly seen only in the lateral views; in AP  views it overlaps the lower end of femur. It lies about  1 cm above the knee joint.   Bilateral separation of the superolateral angles of the  patellae is known as bipartite patella. The small fragment  may be further subdivided to form the multipartite   patella. This is due to failure of the ossific centers to   3 Upper end of tibia , including the two condyles,  intercondylar eminence and tibial tuberosity.   4 Upper end of fibula, including the head, neck and  upper part of shaft.   5 Fabella: It is a small, rounded sesamoid bone in the  lateral head of gastrocnemius. It articulates with the  posterior surface of the lateral condyle of femur. It  measures 1-1.5 cm in diameter, and is present in  about 15% individuals. As a rule it is bilateral, and  appears at 12-15 years of age.   1 Knee joint : The joint space varies inversely with the  age. In young adults, it is about 5 mm. It is entirely  due to articular cartilage and not due to menisci.    Note the epiphyses if any, and determine the age  with the help of ossification studied   2 Navicular and cuboid are seen clearly in almost all  the views (Fig. 14.14).   3 Cuneiform bones are seen separately in dorsoplantar  views; they overlap each other in a lateral view.   4 Metatarsals and phalanges are seen separately in  dorsoplantar views, but overlap each other in lateral  views.   The common sesamoids are found on the plantar  surface of the head of first metatarsal bone. They may  also be present in the tendons of tibialis anterior, tibialis  posterior and peroneus longus.   Accessory bones are separate small pieces of bone  which have not fused with the main bone. For example,  os trigonum (lateral tubercle of talus) and os vesalianum  (tuberosity of fifth metatarsal bone).   Note the epiphyses and other incomplete ossification  if any, and determine the age.   Femoral nerve is the nerve of anterior compartment of  thigh. Its cutaneous branch, the saphenous nerve  extends to the medial side of leg and medial border of  foot till the ball of the big toe.   .Roof value: Dorsal division of ventral rami of L2, L3, L4  segments of spinal cord (see Figs 3.3 and 3.11).   Beginning and course: It emerges at the lateral border of  psoas major muscle in abdomen. It passes downwards  between psoas major and iliacus muscles. The nerve  enters the thigh behind the inguinal ligament, lateral  to femoral sheath. It is not a content of femoral sheath  as its formation is behind fascia iliaca.   Termination: It ends by dividing into two divisions 2.5  cm below the inguinal ligament. Both these divisions  end in a number of branches. In between the two  divisions, lateral circumflex femoral artery is present.   Branches: In abdomen, femoral nerve supplies iliacus  muscle. Just above the inguinal ligament, it gives a  branch to pectineus muscle, which passes behind the  femoral sheath to reach the muscle. Its branches in the  thigh are shown in Table Al.l.   Root value: Obturator nerve is a branch of lumbar  plexus. It arises from ventral division of ventral rami  of L2, L3, L4 segments of spinal cord (see Fig. 4.4).   Beginning and course: It emerges on the medial border  of psoas major muscle within the abdomen. It crosses  the pelvic brim to run downwards and forwards on  the lateral wall of pelvis to reach the upper part of  obturator foramen.   Termination: It ends by dividing into anterior and  posterior divisions. In between the divisions, adductor  brevis is seen.   Anterior division: It passes downwards in front of  obturator externus. Then it lies between pectineus and  adductor longus anteriorly and adductor brevis  posteriorly. It gives muscular, articular and vascular  branches.   Posterior division: It pierces the obturator externus and  passes behind adductor brevis and in front of adductor  magnus. It also ends by giving muscular, articular and  vascular branches.    Medial cutaneous nerve of thigh Saphenous (for medial side of leg and medial border of    Root value: Ventral division of ventral rami of L3, L4  nerves.   Course: Runs along medial border of psoas major,  crosses superior ramus of pubis behind pectineus  muscle.   Branches: Deep surface of pectineus, hip joint and  communicating branch to anterior division of obturator  nerve ( see Fig. 4.6).   Course: Enters the gluteal region through greater sciatic  notch above piriformis muscle. Runs between gluteus  medius and gluteus minimus to end in tensor fasciae  latae (see Fig. 5.14).   Branches: It supplies gluteus medius, gluteus minimus  and tensor fasciae latae.   Course: Enters the gluteal region through greater sciatic  notch below piriformis muscle ( see Fig. 5.14).   Branches: It gives a number of branches to the gluteus  maximus muscle only. It is the sole supply to the large  antigravity, postural muscle with red fibres, responsible  for extending the hip joint.   Sciatic nerve is the thickest nerve of the body. It is the  terminal branch of the lumbosacral plexus.   Root value: Ventral rami of L4, L5, SI, S2, S3. It consists  of two parts ( see Figs 5.6 and 5.14).   Tibial part: Its root value is ventral division of ventral  rami of L4, L5, SI, S2, S3, segments of spinal cord  (see Fig. 7.6).   Common peroneal part: Its root value is dorsal division  of ventral rami of L4, L5, SI, S2 segments of spinal cord.   Course: Sciatic nerve arises in the pelvis. Leaves the  pelvis by passing through greater sciatic foramen below  the piriformis to enter the gluteal region (see Fig. 7.7).   In the gluteal region, it lies deep to the gluteus  maximus muscle, and crosses superior gemellus,  obturator internus, inferior gemellus, quadratus  femoris to enter the back of thigh. During its short  course, it lies between ischial tuberosity and greater  trochanter with a convexity to the lateral side. It gives  no branches in the gluteal region.   In the back of thigh, it lies deep to long head of biceps  femoris and superficial to adductor magnus (see Fig. 7.7).   Termination: It ends by dividing into its two terminal  branches in the back of thigh.   Branches: The branches of sciatic nerve are shown in  Table A1.3.    Root value: Ventral division of ventral rami of L4, L5,  SI, S2, S3, segments of spinal cord.   Beginning: It begins as the larger subdivision of sciatic  nerve in the back of thigh (see Fig. 6.7).   Course: It has a long course first in the popliteal fossa  and then in the back of leg.   Popliteal fossa: The nerve descends vertically in the  popliteal fossa from its upper angle to the lower angle.   Long head of biceps femoris, semitendinosus,  semimembranosus, ischial part of adductor magnus   It lies superficial to the popliteal vessels. It continues  in the back of leg beyond the distal border of popliteus  muscle ( see Fig. 6.7).   In back of leg: The nerve descends as the neurovascular  bundle with posterior tibial vessels. It lies superficial  to tibialis posterior and deep to flexor digitorum longus.  Lastly it passes deep to the flexor retinaculum of ankle  (see Figs 9.2 and 9.7).   Termination: The tibial nerve terminates by dividing into  medial plantar and lateral plantar nerves as it lies deep  to the flexor retinaculum.   This is the smaller terminal branch of sciatic nerve. Its  root value is dorsal division of ventral rami of L4, L5,  SI, S2 segments of spinal cord.   Begimting: It begins in the back of thigh as a smaller  subdivision of the sciatic nerve.   Course: It lies in the upper lateral part of popliteal fossa,  along the medial border of biceps femoris muscle. It  turns around the lateral surface of fibula. Then it lies in  the substance of peroneus longus muscle (see Fig. 6.4).   Termination: Ends by dividing into two terminal  branches, i.e. superficial peroneal and deep peroneal  nerves (see Fig. 8.9).   The deep peroneal nerve is the nerve of the anterior  compartment of the leg and the dorsum of the foot. It  corresponds to the posterior interosseous nerve of the  forearm. This is one of the two terminal branches of  the common peroneal nerve given off between the  neck of the fibula and the peroneus longus muscle.   Course and relations: The deep peroneal nerve begins  on the lateral side of the neck of fibula under cover of    the upper fibres of peroneus longus. It enters the  anterior compartment of leg by piercing the anterior  intermuscular septum. It then pierces the extensor  digitorum longus and comes to lie next to the anterior  tibial vessels (see Fig. 14.4).   In the leg, it accompanies the anterior tibial artery  and has similar relations. The nerve lies lateral to the  artery in the upper and lower third of the leg, and  anterior to the artery in the middle one-third.   The nerve ends on the dorsum of the foot, close to  the ankle joint, by dividing into the lateral and medial  terminal branches (see Fig. 8.4).   The lateral terminal branch turns laterally and ends  in a pseudoganglion deep to the extensor digitorum  brevis. Branches arise from the pseudoganglion and  supply the extensor digitorum brevis and the tarsal  joints.   The medial terminal branch ends by supplying the  skin adjoining the first interdigital cleft and the  proximal joints of the big toe.   2 The extensor digitorum brevis (on the dorsum of  foot) is supplied by the lateral terminal branch of  the deep peroneal nerve.   Cutaneous branches: The lateral terminal branch of the  deep peroneal nerve ends by forming the dorsal digital  nerves for the adjacent sides of the big toe and second  toe (see Fig. 8.2).   It is the smaller terminal branch of the common  peroneal nerve (see Fig. 8.9).   Origin: It arises in the substance of peroneus longus  muscle, lateral to the neck of fibula.   Course: It descends in the lateral compartment of leg  deep to peroneus longus. Then it lies between peroneus  longus and peroneus brevis muscles and lastly between  the peronei and extensor digitorum longus.   It pierces the deep fascia in distal one-third of leg  and descends to the dorsum of foot.   It gives cutaneous branches (see Fig. 8.2) to most of the  dorsum of foot including the digital branches to medial  side of big toe, adjacent sides of 2nd and 3rd; 3rd and  4th and 4th and 5th toes. The nail beds are not supplied  as these are supplied by medial plantar for medial 3%  and by lateral plantar for lateral 1% toes. Adjacent sides  of big and second toes are supplied by deep peroneal  nerve. The medial border of foot is supplied by  saphenous and lateral border by sural nerves.   The medial and lateral plantar nerves are the terminal  branches of the tibial nerve. These nerves begin deep  to the flexor retinaculum.    Medial plantar nerve: It is the larger terminal branch of  tibial nerve. Its distribution is similar to median nerve  of the hand. It lies between abductor hallucis and flexor  digitorum brevis and ends by giving muscular,  cutaneous and articular branches (see Fig. 10.4b).   Branches: The branches of medial plantar nerve are  shown in Table A1.6.   Lateral plantar nerve: It is the smaller terminal branch of  tibial nerve, resembling the ulnar nerve of the hand in  its distribution. It runs obliquely between the first and  second layers of sole till the tuberosity of fifth metatarsal  bone, where it divides into its superficial and deep  branches (see Fig. 10.6b).   Branches: The structures supplied by the trunk, and its  two branches are given in Table A1.7.   — Tarsometatarsal, metatarsophalangeal and  interphalangeal joints of medial 2/3rd of foot    • Femoral nerve supplying the quadriceps femoris  through L2, L3, L4 segments of spinal cord is  tested by doing the 'patellar jerk'. The ligamentum  patellae is hit by the hammer and the contraction  of the quadriceps is felt with extension of knee  (see Fig. 3.30).   • Since obturator nerve supplies both the hip and  knee joints, pain of one joint may be referred to  the other joint.   • The paralysis of left superior gluteal nerve leads  to paralysis of left gluteus medius and minimus   1 st and 2nd plantar interossei: 4th layer  1st, 2nd, 3rd, dorsal interossei: 4th layer  2nd, 3rd, 4th lumbricals: 2nd layer  Adductor hallucis: 3rd layer    muscle. During walking when the body is  supported on left foot, the right unsupported side  of the pelvis droops, causing inability to walk with  right foot. This is called positive Trendelenburg’s test  (see Fig. 5.12)   • Sleeping foot: Sometimes it happens that one is  awake but the foot sleeps. Sciatic nerve lies on  quadratus femoris and adductor magnus. Between  the two muscles, the nerve lies on the hard femur.  So the nerve gets pressed between the femur and  the hard edge of table, chair or bed. There is  numbness of the lower limb till the foot is hit  against the ground a few times. The sensations  come back (see Fig. 7.3).   • Injury: Injury to sciatic nerve leads to paralysis of  hamstrings and all muscles of the leg and foot  leading to "foot drop" (see Fig. 7.11).   • Sciatica: Is the name given when there is radiating  pain in the back of lower limb. It may be due to  slip disc.   • Common peroneal nerve is the commonest nerve  to be paralysed. This is injured due to fracture of  neck of fibula, 'lathi injury' on the lateral side of  knee joint or due to plaster on the leg. In the last  case, the nerve gets compressed between hard  plaster and neck of fibula. To prevent this cotton  must be placed on the upper lateral side of the leg  (see Fig. 8.9).   Motor loss: To dorsiflexors and evertors of foot.  The typical position of the foot is "foot drop";  sensory loss is to the back of leg; lateral side of leg  and most of dorsum of foot.   • Paralysis of muscles of the anterior compartment  of the leg results in loss of the power of  dorsiflexion of the foot. As a result the foot is  plantar flexed. The condition is called as "foot  drop" (see Fig. 8.10).    • The motor and sensory loss in case of injury to  the various nerves is shown in Table A1.8.   • Thus most of the muscles of the lower lim b are  supplied by sciatic nerve except the adductors of  thigh and extensors of knee joint.   • Arterial occlusive disease of the lower limb:  Occlusive disease causes ischaemia of the muscles  of lower limb leading to cramp-like pain. The pain  disappears with rest but comes back with activity.  The condition is called 'intermittent claudication'.   • Palpation of dorsalis pedis artery and posterior  tibial artery gives information about peripheral  arterial diseases (see Fig. 8.11).   • Sympathetic innervation of the arteries: Thoracic  10-12 and L1-L3 segments provide sympathetic  innervation to arteries of lower limb. Preganglionic  fibres relay in the ganglia associated with these  segments. Postganglionic fibres reach blood  vessels via branches of lumbar and sacral plexuses.   • Femoral artery receives postganglionic fibres from  femoral and obturator nerves.   • Arteries of the leg receive postganglionic fibres  via the tibial and common peroneal nerves.   • Lumbar sympathectomy for occlusive arterial  disease: Sympathectomy, i.e. removal of L2 and  L3 ganglia with intervening sympathetic trunk is  advised for this condition. This increases the  collateral circulation. LI ganglion is not removed  as it is responsible for ejaculation.   • Blood supply to muscles of back of thigh reaches  through a rich anastomosis (see Fig. 7.14) formed  by:   • Excessive fluid from knee joint can be aspirated  by putting in a needle in the joint cavity from its  lateral side.   flexors of ankle joint and evertors of foot  Foot drop occurs   Common peroneal Dorsiflexors of ankle, evertors of foot  and foot drop occurs    Anterior side of thigh, medial side of leg till ball of big toe   Back of leg, lateral side of leg, most of dorsum of  foot, sole of foot    Lateral and anterior sides of leg, most of dorsum of  foot, most of digits    Tibial Plantar flexors of ankle, intrinsic muscles of sole Skin of sole. Later trophic ulcers develop   Obturator Adductors of thigh except hamstring part of Small area on the medial side of thigh    Policeman's heel: Plantar aponeurosis is attached to  posterior tubercle of calcaneus and to all five digits.  In plantar fasciitis, there is pain in the heel. Since  policeman has to stand for long hours, they often  suffer from it.   Dipping gait: Gluteus medius and gluteus  minimus support the opposite side of the pelvis,  when the foot is raised during walking. If these two  muscles get paralysed on right side, walking with  left limb becomes difficult, as that limb dips down,  while attempting to lift it. Walking with right leg is  normal as this leg is supported by the normal left  muscles (see Fig. 5.12).   Weaver's bottom: Inflammation of the bursa over  the ischial tuberosity. Since weavers have to sit for a  long time, they suffer from it more often.   Meralgia parasthetica: Lateral cutaneous nerve  of thigh may pierce the inguinal ligament and it may  get pressed and cause irritation over lateral side of  upper thigh (see Fig. 3.20).   Housemaid knee: Inflammation of prepatellar  bursa (see Fig. 3.6). It used to be common in  housemaids as they had to sweep the floor with their  knees bent acutely.   Clergyman's knee: Inflammation of subcutaneous  infrapatellar bursa as he would sit for prayers with  bent knees   Close-pack position of ankle joint: Dorsiflexed  ankle joint when anterior wide trochlear area of talus  fits tightly into posterior narrow articular area of  lower end of tibia.   Inversion injuries more common than eversion  injuries: Inversion is accompanied by plantar flexion.  During plantar flexion the narrow posterior trochlear  area of talus lies loosely in the anterior wide articular  area of lower end of tibia. So inversion injuries are  common.    Fresher's syndrome: Overexertion of the muscles  of anterior compartment of leg causes oedema of leg  as these are enclosed in tight compartment of deep  fascia. This results in pain in the leg. Fresher's are  students who are just admitted in the colleges. They  are compelled to run by the senior students. So it  occurs in them.   Sites of intramuscular injections: In upper lateral  quadrant of gluteal region into the gluteus medius.  Also into the vastus lateralis (see Fig. 5.9).   Sites of pulse palpation in lower limb: Femoral  artery, popliteal artery, posterior tibial and  dorsalis pedis arteries. Popliteal artery is used for  auscultation to measure blood pressure in lower  limb.   Cut openlvenesection: A small cut given in great/  long saphenous vein to insert a cannula for giving  intravenous transfusions. Since position of this vein  is constant, anterior to medial malleolus, the great  saphenous vein is used for cut-open.   Tarsal tunnel syndrome: The syndrome occurs  due to compression of tibial nerve within the fibro-  osseous tunnel under the flexor retinaculum of ankle  joint. This is associated with pain and parasthesia in  the sole of the foot often worse at night.   Injury to medial meniscus: The medial meniscus  is more vulnerable to injury than the lateral meniscus,  because of its fixity to the capsule and tibial collateral  ligament. The lateral meniscus is protected by the  popliteus which pulls it backwards so that it is not  crushed between the articular surfaces (see Fig. 2.18).   Cruciate ligaments: Tear of anterior cruciate  ligament leads to abnormal anterior mobility while  tear of posterior ligament leads to abnormal posterior  mobility of tibia (see Fig. 12.15).   Pes planus: Absence or collapse of the arches leads  to flat foot (pes planus) (see Fig.13.8).   It is the continuation of external iliac artery, begins  behind the inguinal ligament at the midinguinal point  Femoral artery, courses through femoral triangle and  adductor canal. Then it passes through opening in  adductor magnus to continue as the popliteal artery   Largest branch of femoral artery which descends  posterior to femoral vessels, and ends as the  fourth perforating artery   It is the continuation of femoral artery and lies in  the popliteal fossa. Popliteal artery ends by dividing  into anterior tibial artery and posterior tibial artery  at the distal border of popliteus muscle    Smaller terminal branch of popliteal artery reaches  the front of leg through an opening in the  interosseous membrane. Runs amongst muscles  of front of leg till midway between medial and lateral  malleoli, where it ends by changing its name to  dorsalis pedis artery   Continuation of anterior tibial artery. Runs along  medial side of dorsum of foot to reach proximal end  of 1st intermetatarsal space where it enters the  sole. In the sole it completes the plantar arch    It begins as the larger terminal branch of popliteal  artery at the distal border of popliteus muscle. It  descends down medially between the long flexor  muscles to reach midway between medial malleolus  and medial tubercle of calcaneus where it ends by  dividing into medial plantar and lateral plantar  arteries   Largest branch of popliteal artery given off 2.5 cm  below lower border of popliteus   In femoral triangle, femoral artery gives three  superficial branches, e.g. superficial external  pudendal, superficial epigastric and superficial  circumflex iliac, and three deep branches, e.g.  profunda femoris, deep external pudendal and  muscular branches. In adductor canal, femoral  artery gives muscular and descending genicular  artery   Supplies skin of anterior abdominal wall as it  passes towards epigastric region   Branches are medial circumflex femoral, lateral  circumflex femoral, 1st, 2nd and 3rd perforating.  All these branches supply all muscles of thigh  and muscles attached to trochanters   Cutaneous branches for skin of popliteal fossa  Muscular branches for the muscles of the fossa   Muscular to the muscles of anterior compartment  of leg. Cutaneous to the skin of leg. Articular to  the knee joint through anterior and posterior tibial  recurrent branches. Also to the ankle joint through  anterior medial and anterior lateral malleolar  branches   Two tarsal branches for the intertarsal joints.  Arcuate artery runs over the bases of metatarsal  bones and gives off 2nd, 3rd and 4th dorsal  metatarsal arteries. 1st dorsal metatarsal artery  gives digital branches to big toe and medial side  of 2nd toe   Peroneal artery is the largest branch. Nutrient  artery to tibia. Articular branches to the knee joint  and ankle joint. Muscular branches to the  neighbouring muscles    Muscular branches to muscles of posterior and  lateral compartments. Cutaneous to skin of leg.  Articular to ankle joint. Perforating branch enters   the front of leg through a hole in the interosseous  membrane to assist the dorsalis pedis artery   The smaller terminal branch of posterior tibial artery  given off under flexor retinaculum. Runs along the  medial border of foot and ends by giving digital  arteries   Muscular branches to muscles of medial side of  foot. Cutaneous branches to medial side of sole  and digital branches to medial 3 A A> digits. Also  gives branches to the joints of foot   The large terminal branch of posterior tibial artery  given off under the flexor retinaculum. It runs laterally  between muscles of 1st and 2nd layers of sole till the  base of 5th metatarsal bone by becoming continuous  with the plantar arch   Muscular branches to muscles of sole, cutaneous  branches to skin and fasciae of lateral side of  sole   It is the direct continuation of lateral plantar artery  and is completed medially by dorsalis pedis artery   The arch lies between 3rd and 4th layers of muscles  of sole. The deep branch of lateral plantar nerve  lies in its concavity   Four plantar metatarsal arteries, each of them  gives two digital branches for adjacent sides of  two digits, including medial side of big toe and  lateral side of little toe    A. Match the following on the left side with their  appropriate answers on the right side.   b. Lymph vessels connecting superficial inguinal  lymph nodes with deep inguinal lymph nodes   c . The distal fragment of the bone is rotated  laterally   a. It reaches gluteal region by passing through  greater sciatic foramen above the piriformis  muscle   c. At the back of the thigh it is crossed by  semitendinosus   a. Conveys fibres from the dorsal divisions of  ventral rami of L4, L5, SI and S2    b. May get injured in the fracture of neck of fibula   d. Injury results in sensory loss on the whole of the  dorsum of foot   b. Pulls the medial meniscus backwards and  prevents it from being trapped at the beginning  of flexion   c. Initiates flexion of knee joint by unlocking the  locked knee   d. Is innervated by a branch from the common  peroneal nerve   • Crock HV. An atlas of the arterial supply of the head and neck of femur in man. Clin orthop 1980; 152:17-25.   • Eckhoff PG, Kramer RC, Watkins JJ, Alongi CA, Van Gerven DP. Variation in femoral anteversion. Clin Anat 1994; 7:72-5.   • Gardner E, Gray DJ. The innervation of the joints of the foot. Anat Rec 1968; 161:141-8.   • Gupte CM, Bull AMJ, Thomas RD, Amis AA. A review of the function and biomechanics of the meniscofemoral ligaments.  Arthroscopy 2003; 19:161-71.   • Jayakumari S, Suri RK, Rath G, Arora S. Accessory tendon and tripartite insertion of pattern of fibularis longus muscle, A  case report. Int } Morphol 2006; 24: 633-636.   • Joseph J. Movements at the hip joint. Ann R Coll Surg Eng , 1975; 56:192-201   • Kakar S, Garg K, Raheja S. Functional anatomy of human foot in relation to dimensions of the sesamoid bones, Ann Natl  Acad Med Sci (India) 1998; 34 (3): 157-161.   • Raheja S, Choudhry R, Singh P, Tuli A, Kumar H. Morphological description of combined variation of distal attachments  of fibulares in a foot. Surg radial Anat 2005; 27: 158-160   • Rajendran K. Mechanism of locking at the knee joint. / Anat 1985; 143:189-94.   • Sarrafian SK. Anatomy of the Foot and Ankle , Descriptive , Topographic , Functional , 2nd edn. Philadelphia: Lippincott 1993.   • Watanabe M, Takedas S, Ikeuchi H. Atlas of Arthroscopy. Berlin: Springer-Verlag 1979.   The abdomen is the lower part of the trunk and lies  below the diaphragm. It is divided by the plane of  the pelvic inlet into a larger upper part, the abdomen  proper, and a smaller lower part, the true or lesser pelvis  and perineum. The abdomen is bounded to a large extent  by muscles, which can easily adjust themselves to  periodic changes in the capacity of the abdominal cavity.  They can thin out to accommodate distensions of the  abdomen imposed by flatus or gas, fat, foetus and fluid.  The abdomen contains the greater parts of the digestive  and urogenital systems. In addition, it also contains the  spleen, the suprarenal glands, and numerous lymph  nodes, vessels and nerves.   The abdominal wall is made up of the following six  layers.   4 A continuous layer of fascia, named regionwise  as the diaphragmatic fascia, fascia transversalis; fascia  iliaca; anterior layer of thoracolumbar fascia, and pelvic  fascia,   6 The peritoneum which provides a slippery surface  for the movements of the abdominal viscera  against one another.   The abdominal cavity is much more extensive than  what it appears to be when seen from the outside. It  projects upwards deep to the costal margin to reach  the diaphragm. It also projects downwards as the pelvic  cavity within the bony pelvis. Thus a considerable part  of the abdominal cavity is overlapped by the thoracic  bony cage above, and by the bony pelvis below.   The importance of the abdomen is manifold. To a  physician, no examination is ever complete until he/  she has thoroughly examined and auscultated the  abdomen by the stethoscope (Greek look at breast) of    the patient. In fact, the patient, irrespective of his  complaints, is never satisfied without an examination  of his/her abdomen. To an obstetrician and  gynaecologist, the importance of the abdomen is  obvious. The surgeon considers the abdomen as an  enigma because in a good proportion of his/her cases,  the cause of abdominal pain, or the nature of an  abdominal lump, may not be decided in spite of all  possible investigations. Laparotomy, i.e. opening up of  the abdomen by a surgeon, may reveal the disease in  many obscure cases, but not in all of them. In the course  of evolution, adoption of the erect posture by man has  necessitated a number of structural modifications in the  abdominal wall and pelvis, some of which will be  mentioned in the appropriate sections.    The various bones present in relation to the abdomen  are the lumbar vertebrae, the sacrum, and the bony  pelvis. These are described below. The lower ribs and  costal cartilages are also closely related to the  abdominal wall. These have already been considered  along with the Thorax (Section 2) in Volume 1.   There are five lumbar (Latin loin) vertebrae, of which  the first four are typical, and the fifth is atypical. A  lumbar vertebra is identified by (a) its large size, and  (b) the absence of costal facets on the body (c) absence  of foramen in transverse process.   1 The body is large, and is wider from side to side than  from before backwards. The height of the body is  slightly greater anteriorly than posteriorly; this  difference contributes to the forward convexity of  the lumbar spine (Figs 15.1a and b).    Figs 15.1 a and b: Typical lumbar vertebra: (a) Seen from above,  and (b) seen from the lateral side    7 The superior articular processes lie farther apart than  the inferior. Each process bears a concave facet facing  medially and backwards. The posterior border is  marked by a rough elevation, the mammillary  process.   8 The inferior articular processes lie nearer to each other  than the superior. Each process bears a convex facet  facing laterally and forwards.   a. The transverse processes are thick, short and  pyramidal in shape. Their base is attached to the  whole thickness of the pedicle and encroaches on  the side of the body (Fig. 15.2a).   b. The distance between the inferior articular processes  is equal to or more than the distance between the  superior articular processes.   c. The spine is small, short and rounded at the tip.   2 Other features of the fifth lumbar vertebra are as  follows.   a. The body is the largest of all lumbar vertebrae. Its  anterior surface is much extensive than the  posterior surface. This difference is responsible for  the creation of the sharp lumbosacral angle and is  120° in an adult.    2 The vertebral foramen is triangular in shape, and is  larger than in the thoracic region; but is smaller than  in the cervical region.   3 The pedicles are short and strong. They project  backwards from the upper part of the body, so that  the inferior vertebral notches are much deeper than  the superior.   4 The laminae are short, thick and broad. They are  directed backwards and medially to complete the  vertebral foramen posteriorly. The overlapping  between the laminae of the adjoining vertebrae is  minimal.   5 The spine forms a vertical quadrilateral plate, directed  almost backwards and only slightly downwards. It  is thickened along its posterior and inferior borders.   6 The transverse processes are thin and tapering, and  are directed laterally and slightly backwards. These  develop from the costal element and are homologous  with the ribs in the thoracic region. The postero-  inferior aspect of the root of each transverse process  is marked by a small, rough elevation, the accessory  process, which represents the true transverse process  of the vertebra as these develop from the transverse  element of vertebra. The length of the transverse  processes increases from vertebra LI to L3 and,  thereafter, it decreases (Fig. 15.1b).    Figs 15.2a and b: Fifth lumbar vertebra: (a) Seen from above,  and (b) seen from the lateral side   c. The superior articular facets look more backwards  than medially, and the inferior articular facets look  more forwards than laterally, as compared to other  lumbar vertebrae (Fig. 15.2b).   1 The upper and lower surfaces lie contact with the  intervertebral discs.   2 The upper and lower borders give attachment to the  anterior and posterior longitudinal ligaments in front  and behind, respectively.   3 Lateral to the anterior longitudinal ligament, the right  crus of the diaphragm is attached to the upper three  vertebrae, and the left crus of the diaphragm to the  upper two vertebrae.   4 Behind the line of the crura, the upper and lower  borders of all the lumbar vertebrae give origin to the  psoas major (Fig. 15.3).   5 Across the constricted part of the body on either side  tendinous arches are attached. The lumbar vessels , and  the grey ramus communicansfrom the sympathetic chain ,  pass deep to each of these arches.   The part of vertebral canal formed by the first lumbar  vertebra contains the conus medullaris. The part formed  by lower four vertebrae contains the cauda equina. The  canal of all the lumbar vertebrae contains the spinal  meninges.   1 The tips of the transverse processes of all lumbar  vertebrae give attachment to the middle layer of the  lumbar fascia. In addition, the tip of the first process  gives attachment to the medial and lateral arcuate  ligaments , (see Fig. 26.1) and the tip of the fifth process  to the iliolumbar ligament (see Fig. 34.7).   2 The faint vertical ridge on the anterior surface of each  transverse process gives attachment to the anterior  layer of the lumbar fascia. Medial to the ridge, the  anterior surface gives origin to the psoas major , and  lateral to the ridge to the quadratus lumborum  (Fig. 15.3).   3 The posterior surface is covered by deep muscles of  the back, and gives origin to the fibres of the  longissimus thoracis. The accessory process gives  attachment to the medial intertransverse muscle.   4 The upper and lower borders provide attachment to  the lateral intertransverse muscles.   1 The concave articular facets permit some rotation as  well as flexion and extension.   2 The mammillary process gives attachment to the  multifidus and to the medial intertransverse muscles.    A lumbar vertebra ossifies from three primary  centres—one for the body or centrum and one each  for each half of the neural arch. These appear in the  third month of foetal life. The two halves of the neural  arch fuse with each other, posteriorly during the first  year. Fusion of the neural arch with the centrum  occurs during the sixth year. The posterolateral parts  of the body develop from the centre for the neural  arch.   1. An upper annular epiphysis for the upper  surface of the body.   2. A similar epiphysis for the lower surface of the  body.   3 and 4. One centre for the tip of each transverse  process.    • The lumbar region is a common site of a number  of developmental deformities, causing symptoms  ranging from simple backache to serious paralytic  manifestations.   • Th e fifth lumbar vertebra or its transverse process  may be fused, on one or both sides, with the  sacrum. Sometimes the transverse process may  articulate with the ala of the sacrum or with the  ilium. This may press on the fifth lumbar nerve.   Sometimes the body ossifies from two primary  centres, and if one centre fails to develop, it results  in a ''hemivertebra''.   • The two halves of the neural arch may fail to fuse  leaving a gap in the midline. This is called spina  bifida. Meninges and spinal cord may herniate out  through the gap.   • Protrusion of meninges alone results in the  formation of a cystic swelling filled with  cerebrospinal fluid. This swelling is called  meningocoele (Fig. 15.4a). When the spinal cord is  also present in the swelling the condition is called  meningomyelocoele (Fig. 15.4b). The central canal of  the herniated part of the cord may be dilated. This  condition is called syringomyelocoele. At times  the spinal cord may itself be open posteriorly. The  condition is then called myelocoele . Sometimes a  spina bifida is present, but there is no protrusion  through it so that there is no swelling on the  surface. This is referred to as spina bifida occulta.   • Sometimes the greater part of the fifth lumbar  vertebra slips forwards over the sacrum. Normally  the tendency to forward slipping is prevented by  the fact that the inferior articular processes of the  fifth lumbar vertebra lie behind the superior  articular processes of the first sacral vertebra. At  times, however, the inferior articular processes,  spine and laminae of the fifth lumbar vertebra are  separate from the rest of the vertebra (due to an  anomaly in the mode of ossification). The body of  the vertebra can now slip forwards leaving the  separated parts behind (Fig. 15.5).   • Spondylolisthesis may be the cause of backache  and of pain radiating along the course of the sciatic  nerve known as sciatica.   • Fracture-dislocation of lumbar vertebrae results  in the cauda equina syndrome (Fig. 15.6). It is  characterized by:   c. Sphincter disturbances in the form of  incontinence of urine and faeces.   • In the young adults, the discs are very strong and  cannot be damaged alone. However, after the  second decade, degenerative changes set in  resulting in necrosis, with sequestration of nucleus  pulposus, and softening and weakness of the  annulus fibrosus. Such a disc is liable to internal or  eccentric displacement or external derangements  resulting in prolapse due to rupture of annulus  fibrosus even after minor strains.   • The unequal tension in the joint in internal  derangement leads to muscle spasm and violent  pain of acute lumbago.   • Disc prolapse is usually posterolateral (Fig. 15.7).  This presses upon the adjacent nerve roots and  gives rise to referred pain, such as sciatica. Disc  prolapse occurs most commonly in lower lumbar  region and is also common in lower cervical region  (C5-C7). In sciatica, the pain is increased with rise  of pressure in canal (as in sneezing); straight leg  raising tests is positive; and the motor effects, with  loss of power and reflexes, may follow.   • The spine of thoracic vertebrae may point to one  side. The condition is scoliosis (Fig. 15.8).   • There may be projection of the spines posteriorly  due to osteoporosis of the bodies of vertebrae  leading to kyphosis (Fig. 15.9).   • Anterior convexity of lumbar vertebrae may get  exaggerated, leading to "lumbar lordosis" (Fig. 15.10).   The sacrum (Latin sacred) is a large, flattened, triangular  bone formed by the fusion of five sacral vertebrae. It  forms the posterosuperior part of the bony pelvis,  articulating on either side with the corresponding hip  bone at the sacroiliac joint. The upper part of the sacrum  is massive because it supports the body weight and  transmits it to the hip bones. The lower part is free from  weight, and therefore tapers rapidly (Fig. 15.11).   Being triangular, the sacrum has a base or upper  surface, an apex or lower end, and four surfaces—    pelvic, dorsal and right and left lateral. The pelvic  surface is smooth and concave. The dorsal surface is  irregular and convex. The lateral surface is irregular  and partly articular. The sacrum is divided by rows of  foramina into:   b. A pair of lateral masses formed by fusion of the  transverse processes posteriorly, and of the costal  elements anteriorly.   b. The upper surface of the body of the first sacral  vertebra slopes forwards at an angle of about 30  degrees.   c. The upper end of the sacral canal is directed  almost directly upwards and slightly backwards.   The base is directed upwards and forwards. It is formed  by the upper surface of the first sacral vertebra, and  presents features of a typical vertebra in a modified  form.   1 The body is lumbar in type. It articulates with  vertebra L5 at the lumbosacral joint. The projecting  anterior margin is called the sacral promontory. The  surface slopes forwards at an angle of 30 degrees.   2 The vertebral foramen lies behind the body, and  leads into the sacral canal. It is triangular in shape.   3 The pedicles are short and are directed backwards  and laterally.    6 The superior articular processes project upwards.  The facets on them are directed backwards and  medially.   7 The transverse processes are highly modified. Each  process is massive and fused with the corresponding  costal element to form the upper part of the lateral  mass of the sacrum (Fig. 15.11).   The base of the lateral mass, forms a broad sloping  surface spreading fan wise from the side of the body. It  is called the ala of the sacrum. The ala is subdivided  into a smooth medial part and a rough lateral part.   The apex of the sacrum is formed by the inferior surface  of the body of the fifth sacral vertebra. It bears an oval  facet for articulation with the coccyx.   This is concave and directed downwards and forwards.  The median area is marked by four transverse ridges,  which indicate the lines of fusion of the bodies of the  five sacral vertebrae. These ridges end on either side at  the four pelvic sacral foramina, which communicate with  the sacral canal through the intervertebral foramina. The  bony bars between the foramina represent the costal  elements. Lateral to the foramina, the costal elements unite  with each other and with the transverse processes to  form the lateral mass of the sacrum (Fig. 15.11).   The dorsal surface of the sacrum is rough, irregular and  convex, and is directed backwards and upwards.   1 In the median plane, it is marked by the median sacral  crest which bears 3 to 4 spinous tubercles, representing   the fused spines of the upper four sacral vertebrae.  Below the 4th tubercle, there is an inverted U-shaped  gap in the posterior wall of the sacral canal: this is  called the sacral hiatus. It results from failure of the  laminae of the fifth sacral vertebra to meet posteriorly  (Fig. 15.12).   2 Lateral to the median crest, the posterior surface is  formed by the fused laminae.   3 Lateral to the laminae and in line with the superior  articular process of the first sacral vertebra, there are  four articular tubercles, representing the fused  articular processes of adjacent vertebrae. The inferior  articular processes of the fifth sacral vertebra are free  and form the sacral cornua , (Latin horn like) which  project downwards at the sides of the sacral hiatus.   4 Lateral to the articular tubercles there are four dorsal  sacral foramina. They communicate with the sacral  canal through the intervertebral foramina.   5 Lateral to the foramina, there is the lateral sacral crest  on which there are transverse tubercles, representing  the fused transverse processes.   It is formed by the fused transverse processes and the  costal elements of the sacral vertebrae. It is wide above  and narrow below. The upper wider part bears an  L-shaped auricular surface anteriorly, and a rough,  deeply pitted area posteriorly. The auricular surface is  formed by the costal elements. It articulates with the  auricular surface of the hip bone at the sacroiliac joint.  The posterior, roughened and pitted area is formed by  the transverse processes.   The abrupt medial bend at the lower end of the lateral  surface is called the inferior lateral angle of the sacrum.   It is formed by the sacral vertebral foramina, and is  triangular on cross-section. The upper end of the canal  appears oblique, but actually it is directed upwards in  the anatomical position. Inferiorly, the canal opens at  the sacral hiatus, and laterally it communicates through  the intervertebral foramina with the pelvic and dorsal  sacral foramina.   The sacral canal contains the spinal meninges. The  filum terminale and the subdural and subarachnoid spaces  end at the level of the second sacral vertebra. Therefore,  the lower sacral nerves and filum terminale pierce the  dura and arachnoid at this (S2) level.   1 The anterior and posterior edges of the body of the  first sacral vertebra give attachment to the lowest  fibres of the anterior and posterior longitudinal  ligaments. The lamina of this vertebra provide  attachment to the lowest pair of ligamentum flava.   2 The rough part of the ala gives origin to the iliacus  anteriorly, and attachment to the lumbosacral  ligament posteriorly. The upper part of the ventral  sacroiliac ligament is attached to its margin (Fig. 15.11).   3 The part of the pelvic surface lateral to the bodies of  the middle three pieces of the sacrum gives origin to  the piriformis (Fig. 15.11). The area extends into the  intervals between the pelvic sacral foramina and is  E-shaped.   4 The dorsal surface gives origin to the erector spinae  along a U-shaped line passing over the spinous and  transverse tubercles. The area in the concavity of the  'U' gives origin to the multifidus (Fig. 15.12).   5 The interosseous sacroiliac ligament is attached to the  rough pitted area of the lateral surface, behind the  auricular surface (Fig. 15.12).   6 The lower narrow part of the lateral surface, below  the auricular surface gives origin to the gluteus  maximus ; attachment to the sacrotuberous and  sacrospinous ligaments; and origin to the coccygeus ,  in that order from behind forwards (see Fig. 34.7b).   7 The inferior lateral angle gives attachment to the  lateral sacrococcygeal ligament.   1 The smooth part of the ala is related, from medial to  lateral side, to the sympathetic chain , the lumbosacral  trunk , the iliolumbar artery , and the obturator nerve.  All these structures are overlapped by the psoas  major muscle (Fig. 15.11).   b. The sympathetic trunks along the medial margin of  the pelvic foramina.   c. The peritoneum in front of the bodies of the upper  2Vi pieces, interrupted obliquely by the attachment  of medial limb of the pelvic or sigmoid mesocolon  (see Fig. 18.14).   d. The rectum in front of the bodies of the lower 2Vi  pieces. The bifurcation of the superior rectal artery  lies between the rectum and the third sacral  vertebra.   2 The dorsal sacral foramina transmit the dorsal rami  of the upper four sacral nerves (Fig. 15.12).   a. The 5th sacral nerves which groove the lateral parts  of the fifth sacral vertebra.   The sacrum shows a number of important sex  differences. These are as follows.   1 The relationship of the length and breadth of the  sacrum can be expressed quantitatively by using the  sacral index which is calculated as:   Breadth across the base x 100  Length from promontory to apex   The male sacrum is longer and narrower than in the  female. The average sacral index is about 105 in the  male and about 115 in the female.    2 The width of the body of first sacral vertebra is  greater than that of each ala in the male. In female,  the two are equal.   3 The dorsal concavity of auricular surface is less  marked in male. In both, the auricular surface  extends on to upper three sacral vertebrae.   4 The concavity on the ventral aspect of sacrum is more  uniform, and is shallower in males. In females, the  concavity is irregular especially between SI and S2  and between S3 and S4.   5 The sacrovertebral angle is more prominent in the  female and the downward direction of the pelvic  surface is greater than in the male. The size of pelvic  cavity is more in females.    The ossification of the sacrum should be regarded  as the ossification of five separate vertebrae.  However, the upper 3 vertebrae have additional  primary centres for the costal bars.   Thus there are 21 primary centres; 5 for the bodies,  10 for the arches, and 6 for the costal bars and 14  secondary centres; 10 for the epiphyses of the bodies,   2 for the auricular surfaces, and 2 for the margins  below the auricular surfaces. The primary centres  appear between 2nd and 8th week of foetal life, and  fuse with each other between 2nd and 8th years of  life. The secondary centres appear at puberty and  fuse by 25 years.   The coccyx (Greek cuckoo's beak) is a small triangular  bone formed by fusion of four rudimentary coccygeal  vertebrae, which progressively diminish in size from  above downwards. The bone is directed downwards  and forwards, making a continuous curve with the  sacrum.   The first coccygeal piece is the largest. It is commonly  found as a separate vertebra. The upper surface of its  body forms the base of the coccyx, which articulates with  the apex of the sacrum. Projecting upwards from the  posterolateral side of the base are the coccygeal cornua ,  which represent the pedicles and superior articular  processes. They articulate with the sacral cornua and  are connected to them by intercornual ligaments.  Rudimentary transverse processes project laterally and  slightly upwards from the side of the base. They may  articulate or fuse with the inferior lateral angle of the  sacrum, creating a fifth pair of sacral foramina.   The second, third and fourth coccygeal vertebrae are  mere bony nodules which diminish successively in size  and are usually fused together.   3 Attachment to the dorsal sacrococcygeal ligaments and  the filum terminale at the first piece.   1 Provides insertion to the coccygeus and to the levator  ani on either side.   2 Provides attachment to the ventral sacrococcygeal  ligament over the first two pieces.   3 It is related to the ganglion impar and the glomus  coccygeum. The lateral margins provide attachment  to sacrotuberous and sacrospinous ligaments ( see  Figs 29.3 and 29.11).    The coccyx ossifies from 4 primary centres one for  each segment, which appear between 1st and 20th  years, and fuse with each other between 20th and  30th years. The coccyx is slightly mobile at the  sacrococcygeal joint, but fuses with it late in life.   The bones forming the pelvis, (Latin basin) its division  into the greater and lesser pelvis, and the important  features of the lesser pelvis, including the inlet, outlet  and cavity, are described in Chapter 29. Some other  important aspects of the pelvis are described here.   The importance of the measurements of the pelvis is  mainly obstetric, but also forensic and anthropological.  Pelvimetry can be done in the following ways.   Pelvic measurements in obstetric cases can be done both  externally and internally. External pelvimetry has been  mostly given up because of its limited value. It is helpful  in diagnosis of gross pelvic contraction.   1 The interspinous diameter, between the outer borders  of anterior superior iliac spines, measures 22-25 cm.   2 The intercristal diameter , the widest distance between  the outer borders of the iliac crests, measures  25-28 cm.   3 The external conjugate or Baudelocque's diameter, the  distance between the tip of the spine of vertebra S5  and the upper border of the pubic symphysis,  measures not less than 19 cm.   4 The intertuberous diameter, between the lowermost  and innermost points on the two ischial tuberosities,  measures 10 cm.   5 The anteroposterior diameter of the outlet measures  about 13 cm.   6 The posterior sagittal diameter, from the midpoint  of the intertuberous diameter to the tip of the coccyx,  measures 8-9 cm.   1 The diagonal conjugate is the distance between  midpoint of promontory and lower border of    Table 15.1: Dimensions of the pelvis in female (Figs 15.13a to c)   Oblique diameter, from one iliopubic eminence to the opposite sacroiliac joint   Anteroposterior diameter , from midpoint of vertebra S3 to the posterior surface   Oblique diameter, from the lowest point of one sacroiliac joint to the midpoint of the  opposite obturator membrane   Anteroposterior diameter from the tip of the coccyx to the inferior margin of the pubic   Oblique diameter, from the midpoint of the sacrotuberous ligament on one side to  the junction of the ischiopubic rami on the other side    Figs 15.13a to c: The bony pelvis: (a) Inlet with longest transverse diameter, (b) cavity with all diameters equal, and (c) outlet with  longest anteroposterior diameter    anterior surface of pubic symphysis. Normally, it is  at least 11.5 cm. A rough estimate of the true  conjugate is obtained by deducting 1.5 to 2 cm from  the diagonal conjugate.   2 The interischial spinous diameter of 9 cm, between the  tips of the spines is difficult to assess digitally.   3 In addition, a thorough palpation of the bony pelvis  is done to assess the curvature of the sacrum, the  mobility of the coccyx, the length of sacrospinous  ligament (more than the width of two examining  fingers), and the side wall for any tendency to  funnelling.   1 Gynaecoid type (41.4%): This is normal female pelvis,  the average diameters of which have already been  mentioned. The inlet is round or slightly ovoid with  transverse diameter placed well forward from the  sacrum. The side walls are more vertical than in the  android pelvis.   The inlet is triangular with the greatest transverse  diameter placed much nearer the promontory than  in the gynaecoid pelvis. The subpubic angle and  greater sciatic notches are narrower, so that the cavity  is funnel-shaped and the outlet is reduced in all  diameters.   3 The anthropoid type (23.5%) shows resemblance to  the pelvis of anthropoid apes.   4 The platypelloid type (2.6%) is somewhat opposite to  the anthropoid pelvis.    Out of the various types mentioned, only a gynaecoid  pelvis permits a normal delivery of the child. The other  three represent different types of contracted pelvis.   The most marked of these differences are due to  adaptation of female pelvis for child bearing. Males  have stronger muscles, thicker bones and prominent  bony markings.   As compared to a male pelvis a female pelvis shows  the following differences.   2 Pelvic inlet is heart-shaped in male due to jutting  forwards of sacral promontory. In female it is  transversely oval.   3 Pelvic cavity is smaller and deeper in male (Fig. 15.14a  inset). In female the pelvic cavity is roomier and  shallower (Fig. 15.14b inset), i.e. distance between  inlet and outlet is shorter.   4 The pelvic outlet is smaller with ischial  tuberosities turned inside in male. In female the  pelvic outlet is bigger with everted ischial  tuberosities.   5 Sacrum is longer and narrow in male, while it is  shorter and wider in female.   6 Subpubic angle is narrower, i.e. 50°-60° in male.  The angle is wider, i.e. 80°-85° in female. This is the  most important difference (Figs 15.14a and b).   7 The greater sciatic notch is wider in females (75°)  than in males (50°).   8 The acetabulum is large in males, and its diameter  is approximately equal to the distance from its  anterior margin to the pubic symphysis.   9 The chilotic line extends from the iliopubic  eminence to the iliac crest. In females, the pelvic  part of the chilotic line is longer than the sacral  part.    Figs 15.14a and b: Anterior view of (a) a male pelvis, and (b) a female pelvis   When examining an isolated pelvis students generally  do not orientate it as it is in the intact body. It can be  correctly orientated keeping the following in mind.   1 The anterior superior iliac spines and the pubic  symphysis lie in the same vertical plane. A pelvis  can be correctly oriented by placing these points  against a wall.   2 The pelvic surface of the pubic symphysis faces  backwards and upwards.   3 The plane of the pelvic inlet faces forwards and  upwards at an angle of 50° to 60° with the  horizontal.   4 The plane of the pelvic outlet makes an angle of  15° with the horizontal (see Fig. 29.6).   5 The upper end of the sacral canal is directed  almost directly upwards.   The joints between vertebral bodies are secondary  cartilaginous joints held by the intervertebral discs and  two accessory ligaments, the anterior and posterior  longitudinal ligaments. Intervertebral disc is described  below.   Joints of the vertebral arches are formed by the  articular processes of the adjacent vertebrae. These are  plane synovial joints, permitting gliding movements.  The accessory ligaments include:    The lumbar spine permits maximum of extension,  considerable amount of flexion and lateral flexion, and  least of rotation.   It is a fibrocartilaginous disc which binds the two  adjacent vertebral bodies, from axis or second cervical  vertebra to sacrum. Morphologically, it is a segmental  structure as opposed to the vertebral body which is  intersegmental (Figs 15.15a to c).   Its shape corresponds to that of the vertebral bodies  between which it is placed.   It varies in different regions of the column and in  different parts of the same disc. In cervical and lumbar  regions, the discs are thicker in front than behind, while  in the thoracic region they are of uniform thickness.  The discs are thinnest in the upper thoracic and thickest  in the lumbar region.   The discs contribute about one-fifth of the length of  vertebral column. Such contribution is greater in  cervical and lumbar regions than in thoracic region.   1 Nucleus pulposus is the central part of the disc which  is soft and gelatinous at birth. Its water content is  90% in newborn and 70% in old age. It is kept under  tension and acts as a hydraulic shock-absorber. It  represents the remains of the notochord, and  contains a few multinucleated notochordal cells  during the first decade of life, after which there is  a gradual replacement of the mucoid material by  fibrocartilage, derived mainly from the cells of  annulus fibrosus and partly from the cartilaginous   a. Sympathetic trunk b. Lumbosacral trunk  c. Internal iliac artery d. Obturator nerve   2. Anteroposterior, transverse and oblique diameters  are same in which part of the pelvis?   4. Which of the following is not a layer of lumbar  fascia:    The attachments of the muscles of anterolateral  abdominal wall are given in this chapter. The formation  and contents of rectus sheath are mentioned. The  inguinal canal has been described in detail as its  relations are of importance in the reduction/repair of  the inguinal hernia.   The heading "anterior abdominal wall" usually  includes both the front as well as the side walls of the  abdomen and needs to be called anterolateral abdominal  wall.   Before taking up the description of the abdominal wall  proper it is desirable to draw attention to some surface  landmarks that can be identified in the region.    1 In the anterior median plane, the abdominal wall  extends from the xiphoid process which lies at the  level of the ninth thoracic vertebra to the pubic  symphysis, which lies at the level of the coccyx.  Posteriorly and laterally, the vertical extent of the  abdominal wall is much less, as it is replaced by the  thoracic cage, above and behind; and by the gluteal  region, on the posterior aspect of the lower part  (Fig. 16.1).   2 The superolateral margins of the anterior abdominal  wall are formed by the right and left costal margins .  Each margin is formed by the seventh, eighth, ninth  and tenth costal cartilages. The costal margin  reaches its lowest level in the midaxillary line. Here  the margin is formed by the tenth costal cartilage.    The transverse plane passing through the lowest  part of the costal margin is called the subcostal plane.  It passes through the third lumbar vertebra.   3 The infrasternal or subcostal angle is formed between  the right and left costal margins. The xiphoid process  lies in a depression at the apex of the infrasternal  angle at the level of the ninth thoracic vertebra  (Fig. 16.2).   4 The iliac crest forms the lower limit of the abdominal  wall at the side. The highest point of the iliac crest  lies at the level of the fourth lumbar vertebra slightly  below the normal level of the umbilicus.   5 The anterior superior iliac spine lies at the level of the  sacral promontory.   6 The tubercle of the iliac crest is situated on the outer  lip of iliac crest about 5 cm behind the anterior  superior iliac spine. The intertubercular plane passes  through the tubercles. It passes through the fifth  lumbar vertebra.   7 The inguinal ligament extends from the anterior  superior iliac spine to the pubic tubercle. It is convex  downwards. It is placed at the junction of the anterior  abdominal wall with the front of the thigh (Fig. 16.2).   8 The spermatic cord is a soft rounded cord present  in the male. It can be felt through the skin as it passes  downwards near the medial end of the inguinal  ligament to enter the scrotum. It can be picked up  between the finger and the thumb. When palpated  in this way a firm cord-like structure can be felt  within the posterior part of the spermatic cord. This  is the ductus deferens.   9 The anterior abdominal wall is divided into right and  left halves by a vertical groove. It marks the position  of the underlying linea alba (Latin white line).    Fig. 16.2: Some superficial features in relation to the anterior  abdominal wall    10 A little below the middle of the median furrow  there is an irregular depressed or elevated area  called the umbilicus (Latin navel). It lies at the level  of the junction between third and fourth lumbar  vertebrae.   11 A few centimetres lateral to the median furrow, the  abdominal wall shows a curved vertical groove. Its  upper end reaches the costal margin at the tip of  the ninth costal cartilage. Interiorly it reaches the  pubic tubercle. This line is called the linea  semilunaris. It corresponds to the lateral margin of a  muscle called the rectus abdominis.   12 The transpyloric plane is an imaginary transverse  plane often referred to in anatomical descriptions.  Anteriorly, it passes through the tips of the ninth  costal cartilages; and posteriorly, through the lower  part of the body of the first lumbar vertebra. This  plane lies midway between the suprasternal notch  and the pubic symphysis. It is roughly a hand's  breadth below the xiphisternal joint. It passes  through pylorus of stomach, hila of the kidneys,  fundus of gallbladder neck of pancreas, origin of  coeliac axis and superior mesenteric arteries.   13 The angle between the last rib and outer border of  erector spinae is known as renal angle. It overlies  the lower part of kidney. The twelfth rib may only  be just palpable lateral to erector spinae or may  extend for some distance beyond it.   14 Posterior superior iliac spine lies about 4 cm lateral to  the median plane.   15 Three transverse furrows may be seen crossing the  upper part of rectus abdominis, corresponding to  the tendinous intersections of the muscle. One  usually lies opposite the umbilicus, the other  opposite free end of xiphoid process, and the third  midway between the two (Fig. 16.15).   Give an incision from xiphoid process till the umbilicus.  Make a small circular incision around the umbilicus and  extend it till the pubic symphysis. Carry the incision  laterally from the umbilicus till the lateral abdominal wall  on both sides. Give curved incisions 3 cm below from  anterior superior iliac spine to pubic symphysis on either  side (Fig. 16.3).   Finally give a oblique incision from the xiphoid  process along the costal margin till the lateral abdominal  wall on either side.   Carefully reflect the skin in four flaps leaving both the  layers of superficial fascia on the anterior abdominal wall.   Make a transverse incision through the entire  thickness of the superficial fascia from the anterior  superior iliac spine to the median plane. Raise the lower  margin of the cut fascia and identify its fatty and  membranous layers. Note that the fatty layer is  continuous with the fascia of adjoining parts of the body.   The membranous layer of anterior abdominal wall is  continuous with the similar fascia (Colies’ fascia) of the  perineum. Note its attachment to pubic arch and  posterior margin of perineal membrane (inferior fascia  of urogenital diaphragm).   Locate the superficial inguinal ring immediately  superolateral to the pubic tubercle.   Note the anterior cutaneous branch of the  iliohypogastric nerve piercing the aponeurosis of the  external oblique muscle a short distance superior to  the ring (Fig. 16.4).   The spermatic cord/round ligament of uterus along  with ilioinguinal nerve leave the abdomen through the  superficial inguinal ring. Identify the external spermatic  fascia attaching the spermatic cord to the margins of  the ring (refer to #).   Divide the superficial fascia vertically in the median  plane and in the line of the posterior axillary fold as far  as the iliac crest.   Reflect the fascia by blunt dissection from these two  cuts and find the anterior and lateral cutaneous  branches of the lower intercostal nerves along with  respective blood vessels coming out from the anterior  and lateral regions of the abdominal wall.    The skin of the anterior abdominal wall is capable of  undergoing enormous stretching as is seen in  pregnancy; with accumulation of fat, called obesity or  of fluid called ascitis, and with growth of large intra¬  abdominal tumours.    Undue stretching may result in the formation of  whitish streaks in the skin of the lower part of the anterior  abdominal wall; these are known as lineae olbicantes.   The umbilicus is the normal scar in the anterior  abdominal wall formed by the remnants of the root of  the umbilical cord.   The position of the umbilicus is variable. In healthy  adults it lies in the anterior median line, at the level of  the disc between the third and fourth lumbar vertebrae.  It is lower in infants and in persons with a pendulous  abdomen.   Apart from its embryological importance there are  several facts of interest about the umbilicus. These are:   1 With reference to the lymphatic and venous drainage,  the level of the umbilicus is a watershed. Lymph and  venous blood flow upwards above the plane of the  umbilicus; and downwards below this plane. These  do not normally cross umbilical plane (Fig. 16.5a).   2 The skin around the umbilicus is supplied by  segment T10 of the spinal cord (Fig. 16.4).   3 The umbilicus is one of the important sites at which  tributaries of the portal vein anastomose with  systemic veins ( portocaval anastomoses). In portal  hypertension, these anastomoses open up to form  dilated veins radiating from the umbilicus called  the caput medusae. However, the blood flow in the  dilated veins is normal, and does not break the  barrier of the watershed line (Fig. 16.5b). Direction  of blood flow in superior vena caval obstruction  (Fig. 16.5c); and in inferior vena caval obstruction  shown in Fig. 16.5d.   Figs 16.5a to d: The subcutaneous venous circulation in: (a) Normal subjects, (b) portal obstruction, (c) superior vena caval  obstruction, and (d) inferior vena caval obstruction (arrows indicate the direction of blood flow)   1 Umbilicus is the meeting point of the four (two  lateral, head and tail) folds of embryonic plate.   2 This is also the meeting point of three systems,  namely the digestive (vitellointestinal duct), the  excretory (urachus), and vascular (umbilical vessels).    * Remnants of the vitellointestinal duct may form a  tumour at the umbilicus (raspberry red tumour;  or cherry red tumour). Persistence of a patent  vitellointestinal duct results in a faecal fistula at  the umbilicus (Fig, 16.6).   * Persistence of proximal part of vitellointestinal  duct is Meckel's diverticulum.   * Persistence of the urachus may form a urinary  fistula opening at the umbilicus (Fig. 16.7).   * Umbilical vessels at birth can be identified at the  umbilicus. These are two tortuous umbilical  arteries and a single umbilical vein. For some  clinical conditions, these vessels need to be  catheterized.   * Umbilical hernia is seen if any weakness is present  at the umbilicus.   1 Below the level of the umbilicus, the superficial fascia  of the anterior abdominal wall is divided into a  superficial fatty layer (fascia of Camper) and a deep  membranous layer (fascia of Scarpa). The various  contents of the superficial fascia rim between these  two layers.   The fatty layer is continuous with the superficial fascia  of the adjoining part of the body. In the penis, it is  devoid of fat, and in the scrotum it is replaced by  the dartos muscle.   The membranous layer is continuous below with a  similar membranous layer of superficial fascia of the  perineum known as Colles' fascia. The attachments  of Scarpa's fascia of the abdomen and of Colles' fascia  of the perineum are such that they prevent the  passage of extravasated urine due to rupture of  urethra backwards into the ischiorectal fossa and  downwards into the thigh (Fig. 16.8a). The line of  attachment passes over the following.   a. Holden's line (it begins little lateral to pubic  tubercle and extends laterally for 8 cm);   c. Body of the pubis and the deep fascia on the  adductor longus and the gracilis near their origin;   f. Above the umbilicus the membranous layer  merges with the fatty layer.   2 In the median plane, the membranous layer is  thickened to form the suspensory ligament and  fundiform ligament of the penis or clitoris (Fig. 16.8b).   a. An extremely variable quantity of fat, which tends  to accumulate in the lower part of the abdomen  after puberty.    Membranous layer of superficial fascia of abdomen  is continuous with the superficial perineal pouch via  scrotum and penis. At times the urethra may rupture  and urine extravasates into this space.   The skin of the anterior abdominal wall is supplied by  the lower six thoracic nerves (lower five intercostal and  subcostal) and by the first lumbar nerve in the following  manner.   The anterior cutaneous nerves (seven in number) are  derived from the lower five intercostal nerves, the  subcostal nerve and the iliohypogastric nerve (LI).   T7-T12 nerves enter the abdominal wall from the  intercostal spaces. They pass between internal oblique  and transversus muscle, pierce the posterior lamina of  internal oblique aponeurosis to enter rectus sheath.  Within the sheath, they pass behind rectus abdominis,  then pierce the rectus muscles and the anterior wall of  the rectus sheath close to the median plane, divide into  medial and lateral branches and supply the skin of the  front of the abdomen. They are arranged in serial order;  T7 near the xiphoid process, T10 at the level of  umbilicus, the iliohypogastric nerve 2.5 cm above the  superficial inguinal ring, and others at proportionate  distances between them (Fig. 16.4). Subcostal nerve  supplies pyramidalis while iliohypogastric and  ilioinguinal do not enter rectus sheath. Iliohypogastric  becomes cutaneous 2.5 cm above the superficial  inguinal ring (Fig. 16.9).    Figs 16.8a and b: The extent and attachments of the membranous layer of superficial fascia of the abdomen and perineum in a  male: (a) Anterior view, and (b) sagittal section    The terminal part of the ilioinguinal nerve emerges  through the superficial inguinal ring, pierces the  external spermatic fascia and descends to supply the  skin of the external genitalia and the upper part of the  medial side of the thigh.   The lateral cutaneous nerves are two in number and  are derived from the lower two intercostal nerves (T10,  Til). Each nerve pierces the external intercostal muscle  and divides into a large anterior branch and a smaller  posterior branch, both of which emerge between  the lower digitations of the external oblique muscle and  supply the skin of the side of the abdomen. The larger  anterior branches also supply the external oblique  muscle (Fig. 16.21).   The lateral cutaneous branches of the subcostal and  iliohypogastric (T12, LI) nerves descend over the iliac  crest and supply the skin of the anterosuperior part of  the gluteal region (see Fig. 5.3).   1 The anterior cutaneous arteries are branches of the  superior and inferior epigastric arteries , and accompany  the anterior cutaneous nerves (Fig. 16.10).   2 The lateral cutaneous arteries are branches of the lower  intercostal arteries, and accompany the lateral  cutaneous nerves.   3 The superficial inguinal arteries arise from the  femoral artery and supply the skin of the lower part  of the abdomen. The superficial epigastric artery rims  upwards and medially and supplies the skin up to  the umbilicus. The superficial external pudendal artery  runs medially, to supply the skin of the external  genitalia and the adjoining part of the lower  abdominal wall. The superficial circumflex iliac artery  runs laterally just below the inguinal ligament and  along the iliac crest to supply the skin of the abdomen  and thigh.   The veins accompany the arteries. The superficial  inguinal veins drain into the great saphenous vein  (;see Fig. 3.4).   When the portal vein, or the superior vena cava, or  the inferior vena cava is obstructed, the superficial  abdominal veins are dilated and provide a collateral  circulation. The dilated veins that radiate from the  umbilicus are given the name caput medusae  (Fig. 16.5b). They are seen typically in portal obstruc¬  tion in which blood flow is upwards above the umbili¬  cus, and downwards below the umbilicus. In vena  caval obstructions, the thoracoepigastric veins open up,  connecting the superficial epigastric vein (ending in  great saphenous vein) with lateral thoracic vein  (ending in axillary vein). In superior vena caval  obstruction, the blood in the thoracoepigastric vein    flows downwards, breaking the barrier of watershed line  (Fig. 16.5c). In inferior vena caval obstruction, the  blood flows upwards, once again crossing the  watershed line (Fig. 16.5d).   Lymphatics also pay due respect to the watershed line.  Above the level of the umbilicus the lymphatics run  upwards to drain into the axillary lymph nodes . Below  the level of the umbilicus they run downwards to drain  into the superficial inguinal lymph nodes (Fig. 16.11).   Identify the origin of the external oblique from the lower  eight ribs, and its interdigitations with serratus anterior  in the upper part and with latissimus dorsi in the lower  part of its origin. Separate 1-6 digitations from the ribs.  Cut vertically, through the muscle to the iliac crest  posterior to the sixth digitation. Separate the external  oblique from the iliac crest in front of this. Try to avoid  injury to the lateral cutaneous branches of the subcostal  and iliohypogastric nerves which pierce it close to the  iliac crest.   Reflect the upper part of the external oblique forwards  and expose the deeper internal oblique and its  aponeurosis to the line of its fusion with the aponeurosis  of the external oblique anterior to rectus abdominis. Just  lateral to this line of fusion divide the external oblique  aponeurosis vertically till the pubic symphysis. Turn the  muscle and aponeurosis interiorly. This exposes the  inferior part of the internal oblique and the lowest portion  of aponeurosis of external oblique, i.e. the inguinal  ligament (refer to #).   Identify the deep fibres of the inguinal ligament  passing posteriorly to the pecten pubis. This is the  lacunar ligament or pectineal part of the inguinal  ligament.   The muscle arises by eight fleshy slips from the outer  surfaces middle of the shaft of the lower eight ribs. The  fibres run downwards, forwards and medially  (Fig. 16.12).    The anterolateral abdominal wall is made up mainly  of muscles. On either side of the midline there are four  large muscles. These are the external oblique, the internal  oblique, the transversus abdominis and the rectus  abdominis. Two small muscles, the cremaster and the  pyramidalis are also present. The external oblique, the  internal oblique and the transversus abdominis are  large flat muscles placed in the anterolateral part of the  abdominal wall. Each of them ends in an extensive  aponeurosis that reaches the midline. Here the  aponeuroses of the right and left sides decussate to form  a median band called the linea alba. The rectus  abdominis runs vertically on either side of the linea alba.  It is enclosed in a sheath formed by the aponeuroses of  the flat muscles named above. The various muscles are  considered one by one below. The actions of these  muscles are described later.   1 Most of the fibres of the muscle end in a broad  aponeurosis through which they are inserted from  above downwards into the xiphoid process, linea  alba, pubic symphysis, pubic crest and the pectineal  line of the pubis.   2 The lower fibres of the muscle are inserted directly  into the anterior two-thirds of the outer lip of the  iliac crest.   1 The upper four slips of origin of the muscle  interdigitate with those of the serratus anterior; and  the lower four slips with those of the latissimus dorsi.   2 The junction of the muscle fibres with the  aponeurosis lies:   a. Medial to a vertical line drawn from the ninth  costal cartilage in the upper part.   b. Below a line joining the anterior superior iliac  spine to the umbilicus. Above the ninth costal  cartilage the line curves upwards and medially.   3 Between the anterior superior iliac spine and the  pubic tubercle the aponeurosis has a free inferior  border that is folded on itself to form the inguinal  (Latin groin) ligament. The ligament is described in  detail later.   4 Between the linea semilunaris and the linea alba, the  aponeurosis helps to form the anterior wall of rectus  sheath.   5 Just above the pubic crest the aponeurosis of the  external oblique muscle presents a triangular  aperture called the superficial inguinal ring (Fig. 16.12).   b. The anterior two-thirds of the intermediate area of  the iliac crest, and   1 The uppermost fibres are inserted directly into the  lower three or four ribs and their cartilages.   2 The greater part of the muscle ends in an aponeurosis  through which it is inserted into the seventh, eighth   Upper part of  aponeurosis  forming anterior  and posterior walls  of rectus sheath    and ninth costal cartilages, the xiphoid process, linea  alba, pubic crest and the pectineal line of the pubis  (Fig. 16.13). It does not extend beyond the costal margin.   1 The junction of the muscle fibres with the  aponeurosis is roughly at the lateral border of the  rectus abdominis.   2 The aponeurosis takes part in the formation of rectus  sheath as follows. Up to the lateral margin of rectus  abdominis, the aponeurosis has only one layer.  Thereafter, the arrangement of aponeurosis differs in  its upper and lower parts.   a. Below a level midway between the umbilicus and  the pubic symphysis (lower 1 /4th of the wall) the  aponeurosis remains a single layer. It passes in  front of rectus abdominis to reach linea alba. It,  thus, takes part in forming the anterior wall of  rectus sheath.   b. Above this level, i.e. upper 3/4th of the wall, the  aponeurosis splits into an anterior lamina that  passes medially in front of the rectus abdominis;  and a posterior lamina that lies behind the rectus.  The posterior lamina ends below, at the level  midway between the umbilicus and the pubic  symphysis, in a free curved margin called the  arcuate line or linea semicircularis , or fold of Douglas.  The line is concave downwards.   4 The cremaster muscle is formed by fibres of this  muscle, and is described later.   Lift the internal oblique and cut carefully through its  attachments to the inguinal ligament, iliac crest and  costal margin.   Carefully preserve the nerves of the anterior  abdominal wall which lie between internal oblique and  transversus abdominis. Cut vertically through the  internal oblique from the twelfth costal cartilage to the  iliac crest and reflect the muscle forwards from the  transversus and the nerves.   2 The anterior two-thirds of the inner lip of the iliac  crest.   4 The inner surfaces of the lower six costal cartilages.  The fibres are directed horizontally forwards.   The fibres end in a broad aponeurosis which is inserted  into the xiphoid process, the linea alba, the pubic crest,  and the pectineal line of the pubis (Fig. 16.14).   The lowest fibres of the muscle fuse with the lowest  fibres of the internal oblique to form the conjoint tendon.   1 The aponeurosis of the transversus abdominis takes  part in forming the rectus sheath as follows. Above the  level of the arcuate line (upper 3/4th) the aponeurosis  passes medially behind the rectus abdominis muscle  along with the posterior lamina of the internal oblique  aponeurosis. The lower edge of this part of the  aponeurosis helps to form the arcuate line. In the  uppermost part, some fleshy fibres of the transversus  abdominis may lie behind the rectus abdominis.  Below the level of the arcuate line the aponeurosis  passes in front of the rectus abdominis and helps to  form the anterior wall of the rectus sheath.   2 The neurovascular plane of the abdominal wall lies  between the internal oblique and transversus muscles .  This plane is continuous with the neurovascular  plane of the thoracic wall. Various nerves and vessels  run in this plane.   3 The aponeuroses of three flat muscles seem to end  in the fibrous raphe—the linea alba. Each aponeurosis  is made up of the two laminae, the superficial and  deep laminae. The laminae of the two sides  interdigitate in a manner that the superficial lamina  of one gets continuous with deep lamina of the  opposite side and vice versa. This provides enough  strength to the anterior abdominal wall.   1 Lateral head from the lateral part of the pubic crest  (Fig. 16.15).   Fascia  transversalis  forming lower part  of posterior wall of  rectus sheath   On the front of the wall of the thorax, along a horizontal  line passing laterally from the xiphoid process,  and cutting in that order, the 7th, 6th and 5th costal  cartilages.   1 The inguinal or Poupart's ligament is formed by the  lower border of the external oblique aponeurosis  which is thickened and folded backwards on itself.  It extends from the anterior superior iliac spine to  the pubic tubercle, and lies beneath the fold of the  groin. Its lateral half is rounded and oblique. Its  medial half is grooved upwards and is more  horizontal (Fig. 16.16).   1 The muscle is enclosed in a sheath formed mainly  by the aponeuroses of the three flat muscles of the  abdominal wall. The sheath is described later.   2 Tendinous intersections: These are three transverse  fibrous bands which divide the muscle into smaller  parts. One lies opposite the umbilicus, the second  opposite the free end of the xiphoid process, and the  third in between the two. One or two incomplete  intersections may be present below the umbilicus.  The intersections are actually zigzag in course,  traverse only the anterior half of the muscle, and are  adherent to the anterior wall of rectus sheath.  Embryologically they may represent the segmental  origin of muscle, but functionally they make the  muscle more powerful by increasing the number of  muscle fibres.   1 Support for abdominal viscera: The abdominal muscles  provide a firm but elastic support for the abdominal  viscera against gravity. This is chiefly due to the tone  of the oblique muscles, especially the internal  oblique.   2 Expulsive acts: The oblique muscles, assisted by the  transversus, can compress the abdominal viscera and  thus help in all expulsive acts, like micturition,  defaecation, parturition, vomiting, etc. This is one  of the most important actions of the abdominal  muscles.   3 Forceful expiratory acts: The external oblique can  markedly depress and compress the lower part of  the thorax producing forceful expiration, as in  coughing, sneezing, blowing, shouting, etc. This is  also an important action of the abdominal muscles.   a. Flexion of the trunk or lumbar spine is brought  about mainly by the rectus abdominis.   b. Lateral flexion of the trunk is done by one sided  contraction of the oblique muscles.   c. Rotation of the trunk is produced by a combined  action of the external oblique with the opposite  internal oblique.   a. The fascia lata is attached to the lower border.  Traction of this fascia makes the ligament convex  downwards.   b. The upper surface of the ligament gives origin to  the internal oblique from its lateral two-thirds, to  the transversus abdominis from its lateral one-  third, and to the cremaster muscle from its middle  part.   Relations: The upper grooved surface of the medial  half of the inguinal ligament forms the floor of the  inguinal canal and lodges the spermatic cord or  round ligament of the uterus.   a. The pectineal part of the inguinal ligament or lacunar  ligament is triangular. Anteriorly, it is attached to  the medial end of the inguinal ligament.  Posteriorly, it is attached to the pecten pubis. It is  horizontal in position and supports the spermatic  cord. The apex is attached to the pubic tubercle. The  base is directed laterally. It forms the medial  boundary of the femoral ring. It is reinforced by the  pectineal fascia and by fibres from the linea alba  (Fig. 16.16).   b. The pectineal ligament or ligament of Cooper is an  extension from the posterior part of the base of  the lacunar ligament. It is attached to the pecten    pubis. It may be regarded as a thickening in the  upper part of the pectineal fascia,  c. The reflected part of the inguinal ligament consists of  fibres that pass upwards and medially from the  lateral crus of the superficial inguinal ring. It lies  behind the superficial inguinal ring and in front  of the conjoint tendon. Its fibres interlace with  those of the opposite side at the linea alba.   Identify internal oblique deep to external oblique muscle.  Remove the fascia from the surface of the internal  oblique and its aponeurosis.   Identify the part of the internal oblique which passes  around the spermatic cord. This is the cremaster  muscle.   Dissect the triple relation of internal oblique to the  inguinal canal.    the spermatic cord and testis. It lies deep to the external  spermatic fascia (see Fig. 17.4).   The conjoint tendon is formed by fusion of the lowest  aponeurotic fibres of the internal oblique and of the  transversus muscles, attached to the pubic crest and to  the medial part of the pecten pubis. Medially, it is  continuous with the anterior wall of the rectus sheath.  Laterally, it is usually free. Sometimes it may be  continuous with an inconstant ligamentous band,  named the interfoveolar ligament , which connects the  lower border of the transversus abdominis to the  superior ramus of the pubis. The conjoint tendon  strengthens the abdominal wall at the site where it is  weakened by the superficial inguinal ring (Figs 16.17  and 16.26a).   The cremaster muscle consists of muscle fasciculi  embedded in the cremasteric fascia. The fasciculi form  superficial loops from middle one-third of upper  surface of inguinal ligament and deep loops from pubic  tubercle, pubic crest and conjoint tendon. Here some  fibres may be continuous with the internal oblique or  transversus muscles. The medial ends of the loops are  attached to the pubic tubercle, the pubic crest or the  conjoint tendon (Fig. 16.17).   The muscle is fully developed only in the male. In  the female it is represented by a few fibres only.   Along with the intervening connective tissue, the  muscle loops to form a sac-like cremasteric fascia around   The cremaster helps to suspend the testis and can elevate  it. The muscle also tends to close the superficial inguinal  ring when the intra-abdominal pressure is raised.   Upon stroking the skin of the upper part of the medial  side of the thigh there is reflex contraction of the  cremaster muscle, as evidenced by elevation and  retraction of the testis. The reflex is more brisk in  children. In upper motor neuron lesions above segment  LI, the reflex is lost (Fig. 16.18).    * While examining the abdomen, the knees and hip  must be flexed to relax the abdominal muscles.   * Muscles of anterior abdominal wall contract  during the expiratory phase of respiration.   * Due to lack of exercise, the tone of muscles of the  anterior abdominal wall decreases leading to  protrusion of the wall. This is called visceroptosis.   * The anterior abdominal wall is punctured for  various procedures, like surgeries of gallbladder,  vermiform appendix, etc.   * Supraumbilical median incisions through the linea  alba have several advantages as being bloodless;  safety to muscles and nerves but tend to leave a  postoperative weakness through which a ventral   hernia may develop. Infraumbilical median incisions  are safer because the close approximation of recti  prevents formation of any ventral hernia.  Paramedian incisions through the rectus sheath are  more sound than median incisions. The rectus  muscle is retracted laterally to protect the nerves  supplying it from any injury. In these cases, the  subsequent risk of weakness and of incisional or  ventral hernia are minimal (Fig. 16.19).   * The nerves of anterior abdominal wall, T7-T12 and  LI supply skin, intercostal muscles and parietal  pleura . In addition these supply skin, muscles of  the abdominal wall and parietal peritoneum.  Tubercular infection of lung and pleura may cause  radiating pain in the abdominal wall. Peritonitis  causes reflex contraction of the abdominal muscles.   • During repair of the wounds of anterior abdominal  wall, the nerves T7-T12 need to be anaesthesised  along the costal margin. Iliohypogastric and  ilioinguinal nerves are anaesthesised by a needle  above the anterior superior iliac spine on the  spinoumbilical line.   This is a small triangular muscle. It is rudimentary in  human beings. It arises from the anterior surface of the  body of the pubis. Its fibres pass upwards and medially  to be inserted into the linea alba.   The muscle is supplied by the subcostal nerve (T12).  It is said to be tensor of the linea alba, but the need for  such action is not clear.   The anterior abdominal wall is supplied by the lower  six thoracic nerves or lower five intercostal, and  subcostal; and by the first lumbar nerve through its  iliohypogastric and ilioinguinal branches. These are the  nerves which emerge as cutaneous nerves. Their deep  course is described briefly with the cutaneous nerves  in the beginning of this chapter (Figs 16.9 and 16.20).   1 Two large arteries from above, the superior epigastric  and musculophrenic (Fig. 16.10).   2 Two large arteries from below, the inferior epigastric  and the deep circumflex iliac.   3 Small branches of the intercostal, subcostal and  lumbar arteries, which accompany the corres¬  ponding nerves (Fig. 16.21).    Fig. 16.21 : A transverse section through the lumbar region showing the arrangement of the abdominal muscles and the neurovascular  plane    The superior epigastric artery is one of the two terminal  branches of the internal thoracic artery. It begins in the  sixth intercostal space, and enters the abdomen by  passing behind the seventh costal cartilage between the  costal and xiphoid origins of the diaphragm. It enters  the rectus sheath and runs vertically downwards,  supplies the rectus muscle, and ends by anastomosing  with the inferior epigastric artery. In addition to  muscular and cutaneous branches, it gives a hepatic  branch which runs in the falciform ligament , and an  anastomotic branch, at the level of the xiphoid process,  which anastomoses with the artery of the opposite side.   The musculophrenic artery is the other terminal branch  of the internal thoracic artery. It runs downwards and  laterally behind the seventh costal cartilage, and enters  the abdomen by piercing the diaphragm between the  seventh and eighth cartilages. It continues downwards  and laterally along the deep surface of the diaphragm  as far as the tenth intercostal space. It gives branches to  the diaphragm, the anterior abdominal wall and the  seventh, eighth and ninth intercostal spaces as the  anterior intercostal arteries (Fig. 16.10).   The inferior epigastric artery arises from the external  iliac artery near its lower end just above the inguinal  ligament. It runs upwards and medially in the  extraperitoneal connective tissue, passes just medial to  the deep inguinal ring, pierces the fascia transversalis    at the lateral border of the rectus abdominis and enters  the rectus sheath by passing in front of the arcuate line  (Fig. 16.10). Within the sheath it supplies the rectus  muscle and ends by anastomosing with the superior  epigastric artery. It gives off the following branches.   a. A cremasteric branch to the spermatic cord, in males  or the artery of the round ligament in females.   b. A pubic branch which anastomoses with the pubic  branch of the obturator artery.   d. Cutaneous branches to the overlying skin. The  pubic branch may replace the obturator artery,  and is then known as the abnormal obturator artery.   The deep circumflex iliac artery is the other branch of  the external iliac artery, given off from its lateral side  opposite the origin of the inferior epigastric artery. It  runs laterally and upwards behind the inguinal  ligament, pierces the fascia transversalis, and continues  along the iliac crest, up to its middle where it pierces  the transversus abdominis to enter the interval between  the transversus and the internal oblique muscles. At  the anterior superior iliac spine it anastomoses with the  superior gluteal, the lateral circumflex femoral and  superficial circumflex iliac arteries. Just behind the  anterior superior iliac spine it gives off an ascending  branch which runs upwards in the neurovascular plane.   Identify the rectus abdominis muscle. At the lateral edge  of the rectus abdominis, the aponeurosis of the internal  oblique splits to pass partly posterior and partly anterior  to the rectus abdominis; the anterior layer fusing with  the aponeurosis of external oblique and the posterior  layer with that of the transversus abdominis. This is  how most of the rectus sheath is formed. Identify the  arcuate line midway between umbilicus and pubic  symphysis.   Define the origins of the transversus and follow its  aponeurosis to fuse with that of the internal oblique,  posterior to the rectus abdominis above the arcuate  line and anteriorly to the unsplit aponeurosis of internal  oblique below the line. See that aponeurosis of all three  muscles pass anterior to rectus abdominis below the  arcuate line.   Open the rectus sheath by a vertical incision along  the middle of the muscle. Reflect the anterior layer of  the sheath side ways, cutting its attachments to the  tendinous intersections in the anterior part of the rectus  muscle (Fig. 16.15).   Lift the rectus muscle and identify the 7-11 intercostal  and subcostal nerves entering the sheath through its  posterior lamina, piercing the muscle and leaving  through its anterior wall.   Divide the rectus abdominis transversely at its  middle. Identify its attachments and expose the posterior  wall of the rectus sheath by reflecting its parts superiorly  and inferiorly. Identify and trace the superior and inferior  epigastric arteries.   Define the arcuate line on the posterior wall of the  rectus sheath.   1 It is complete, covering the muscle from end to end.   3 It is firmly adherent to the tendinous intersections of  the rectus muscle (Fig. 16.22).   1 It is incomplete, being deficient above the costal  margin and below the arcuate line.   Fusion of all the aponeuroses in the midline. It is called  as linea alba.   It is called linea semilunaris, it extends from tip of 9th  costal cartilage to pubic tubercle.   Details about the formation of the walls are as follows  (Figs 16.23a and b).   Posterior wall: It is deficient; the rectus muscle rests  directly on the 5th, 6th and 7th costal cartilages.   Anterior wall: External oblique aponeurosis and anterior  lamina of the aponeurosis of the internal oblique.   Posterior wall: Posterior lamina of the aponeurosis of  the internal oblique and aponeurosis of the transversus  muscle (Fig. 16.23b).   Midway between the umbilicus and the pubic sym¬  physis, the posterior wall of the rectus sheath ends in  the arcuate line or linea semicircularis or fold of Douglas.  The line is concave downwards.   Figs 16.23a to c: Transverse sections through the rectus abdominis, and its sheath: (a) Above the costal margin, A of inset,  (b) between costal margin and arcuate line, B of inset and (c) below arcuate line, C of inset   Anterior wall: Aponeuroses of all the three flat muscles  of the abdomen. The aponeuroses of the transversus  and the internal oblique are fused, but the external  oblique aponeurosis remains separate (Fig. 16.23c).   Posterior wall: It is deficient. The rectus muscle rests on  the fascia transversalis.   2 The pyramidalis (if present) lies in front of the lower  part of the rectus abdominis.   1 The superior epigastric artery enters the sheath by  passing between the costal and xiphoid origins of  the diaphragm. It crosses the upper border of the  transversus abdominis behind the seventh costal  cartilage. It supplies the rectus abdominis muscle and  anastomoses with the inferior epigastric artery  (Fig. 16.22).   2 The inferior epigastric artery enters the sheath by  passing in front of the arcuate line.   1 The superior epigastric vena comitantes accompany its  artery and join the vena comitantes of internal  thoracic vein.   2 The inferior epigastric vena comitantes accompany its  artery and join the external iliac vein.   These are the terminal parts of the lower six thoracic  nerves, including the lower five intercostal nerves and the  subcostal nerves (Fig. 16.21).   1 It checks bowing of rectus muscle during its contra¬  ction and thus increases the efficiency of the muscle.   Rectus sheath is formed by decussating fibres from  three abdominal muscles of each side. Each forms a  bilaminar aponeurosis at their medial borders. Fibres  from all three anterior leaves run obliquely upwards,  while the posterior fibers run obliquely downwards at  right angles to anterior leaves.   Both leaves of external oblique aponeurosis and anterior  leaf of internal oblique aponeurosis.   Posterior leaf of aponeurosis of internal oblique and  both leaves of aponeurosis of transversus abdominis.   Fibres of each layer decussate to the opposite side of  the sheath. Fibres also decussate between anterior and  posterior sheaths.   The three lateral abdominal muscles may be said to  be digastric with a central tendon in the form of linea  alba.    Linea alba is a tendinous raphe between xiphoid  process above to symphysis pubis and pubic crest  below. Above the umbilicus the linea alba is broader.  Superficial fibres of linea alba are attached to symphysis  pubis, while deep fibres are attached behind rectus  abdominis to posterior surface of pubic crest.   The inner surface of the abdominal muscles is lined by  fascia which is separated from peritoneum by extra-  peritoneal connective tissue. That part of the fascia which  lines the inner surface of the transversus abdominis  muscle is called the fascia transversalis (Fig. 16.24a).   Anteriorly: It is adherent to the linea alba above the  umbilicus.   Posteriorly: It merges with the anterior layer of the  thoracolumbar fascia and is continuous with the renal  fascia (Fig. 16.24b).   Interiorly: It is attached to the inner lip of the iliac crest  and to the lateral half of the inguinal ligament. At both  these places it is continuous with the fascia iliaca.   Medially it is attached to the pubic tubercle, the pubic  crest and the pectineal line.   Part of it is prolonged into the thigh as the anterior  wall of the femoral sheath.   About 1.2 cm above the midinguinal point there is an  oval opening in the fascia transversalis. This opening  is the deep inguinal ring (Fig. 16.25). The ring lies    immediately lateral to the inferior epigastric artery. It  transmits the spermatic cord in males, and the round  ligament of the uterus in females.   1 A tubular prolongation of the fascia transversalis  surrounds the spermatic cord forming the internal  spermatic fascia.   2 Over the femoral vessels, the fascia transversalis is  prolonged into the thigh as the anterior wall of femoral  sheath (see Fig. 3.14).   The main arteries of the abdominal wall and pelvis lie  inside the fascia transversalis, while the main nerves  are outside. That is why the femoral vessels are inside  the femoral sheath, while the femoral nerve is outside  the sheath (see Fig. 3.10b).   Identify again the superficial inguinal ring above the  pubic tubercle. It lies in the aponeurosis of external  oblique muscle and provides the external spermatic  fascia to the spermatic cord/round ligament of uterus.   Identify internal oblique muscle deep to external  oblique. Note that its fibres lie anterior to deep inguinal  ring, then arch over the inguinal canal and finally fuse  with the fibres of transversus abdominis to form the  conjoint tendon attached to pubic crest and pecten pubis.   Lastly identify the deep inguinal ring in the fascia  transversalis situated 1.2 cm above the midinguinal  point. This fascia provides the internal spermatic fascia  to the spermatic cord/round ligament of uterus.    Figs 16.24a and b: Continuation of the fascia transversalis: (a) Coronal section, and (b) transverse section    This is an oblique intermuscular passage in the lower  part of the anterior abdominal wall, situated just above  the medial half of the inguinal ligament.   Length and direction: It is about 4 cm (1.5 inches) long,  and is directed downwards, forwards and medially  (Figs 16.25a and b).   b. At its medial end by the reflected part of the  inguinal ligament.   It is formed by the arched fibres of the internal oblique  and transversus abdominis muscles (Figs 16.25a and b).   It is formed by the grooved upper surface of the  inguinal ligament; and at the medial end by the lacunar  ligament (Fig. 16.26b).    Figs 16i25a and b: (a) Superficial and deep inguinal rings, and  (b) formation of the roof of inguinal canal    The inguinal canal extends from the deep inguinal  ring to the superficial inguinal ring.   The deep inguinal ring is an oval opening in the fascia  transversalis, situated 1.2 cm above the midinguinal  point, and immediately lateral to the stem of the inferior  epigastric artery.   The superficial inguinal ring is a triangular gap in the  external oblique aponeurosis. It is shaped like an obtuse  angled triangle. The base of the triangle is formed by  the pubic crest. The two sides of the triangle form the  lateral or lower and the medial or upper margins of  the opening. It is 2.5 cm long and 1.2 cm broad at the  base. These margins are referred to as crura . At and  beyond the apex of the triangle, the two crura are united  by intercrural fibres (Fig. 16.12).   2 In its lateral one-third: The fleshy fibres of the internal  oblique muscle (Fig. 16.26a).   1 The spermatic cord in males , or the round ligament of  the uterus in females, enters the inguinal canal through  the deep inguinal ring and passes out through the  superficial inguinal ring (Fig 16.2).   2 The ilioinguinal nerve enters the canal through the  interval between the external and internal oblique  muscles and passes out through the superficial  inguinal ring (Fig. 16.9).   2 The testicular and cremasteric arteries, and the artery  of the ductus deferens.   5 The ilioinguinal nerve, genital branch of the  genitofemoral nerve, and the plexus of sympathetic  nerves around the artery to the ductus deferens and  visceral afferent nerve fibres.   1 The internal spermatic fascia, derived from the fascia  transversalis; it covers the cord in its whole extent  (Figs 16.26a and b).   2 The cremasteric fascia is made up of the muscle loops  constituting the cremaster muscle, and the  intervening areolar tissue. It is derived from the  internal oblique and transversus abdominis muscles.    Figs 16.26a and b: Boundaries of the inguinal canal: (a) Anterior and posterior walls in a horizontal section, and (b) the roof and  floor in a sagittal section    and therefore covers the cord below the level of  these muscles (Fig. 16.17).   3 The external spermatic fascia is derived from the  external oblique aponeurosis. It covers the cord  below the superficial inguinal ring.   The presence of the inguinal canal is a cause of weakness  in the lower part of the anterior abdominal wall. This  weakness is compensated by the following factors.   1 Obliquity of the inguinal canal: The two inguinal rings  do not lie opposite each other. Therefore, when the  intra-abdominal pressure rises the anterior and  posterior walls of the canal are approximated, thus  obliterating the passage. This is known as the flap  valve mechanism.    2 The superficial inguinal ring is guarded from behind  by the conjoint tendon and by the reflected part of  the inguinal ligament.   3 The deep inguinal ring is guarded from the front by the  fleshy fibres of the internal oblique.   4 Shutter mechanism of the internal oblique: This muscle  has a triple relation to the inguinal canal. It forms the  anterior wall, the roof, and the posterior wall of the  canal. When it contracts the roof is approximated to  the floor, like a shutter. The arching fibres of the  transversus also take part in the shutter mechanism  (Fig. 16.22a).   5 Contraction of the cremaster helps the spermatic cord  to plug the superficial inguinal ring ( ball valve  mechanism ).   6 Contraction of the external oblique results in  approximation of the two crura of the superficial  inguinal ring (slit valve mechanism). The integrity of  the superficial inguinal ring is greatly increased by  the intercrural fibres.   7 Hormones may play a role in maintaining the tone of  the inguinal musculature.   Whenever, there is a rise in intra-abdominal pressure  as in coughing, sneezing, lifting heavy weights all these  mechanisms come into play, so that the inguinal canal  is obliterated, its openings are closed, and herniation  of abdominal viscera is prevented.   Inguinal canal represents the passage of gubernaculum  through the abdominal wall. It extends from the caudal  end of the developing gonad (in lumbar region) to the  labioscrotal swelling. In early life, the canal is very short.    As the pelvis increases in width, the deep inguinal ring  is shifted laterally and the adult dimensions of the canal  are attained.    Hernia is a protrusion of any of the abdominal  contents through any of its walls. This is called  external hernia. At times the intestine or omentum  protrudes into the "no entry" zone within the  abdominal cavity itself. The condition is called as  internal hernia.   Hernia consists of a sac, contents and coverings.  Sac is the protrusion of the peritoneum. It comprises  a neck, the narrowed part; and a body, the bigger  part (Fig, 16.28).   Contents are mostly the long mobile, keen to move  out, coils of small intestine or omentum or any other  viscera.   Coverings are the layers of abdominal wall which  are covering the hernial sac.   Irreducibility: In the beginning, the loop of intestine  herniates out but comes back to the abdomen. At  times, the loop goes out but does not return, leading  to irreducible hernia.   Obstruction: The loop may get narrowed in part,  so that contents of the loop cannot move forwards,  leading to obstruction.   Strangulation: When the arterial supply is blocked,  the loop gets necrosed.   • Protrusion of loop of intestine within a "no entry"  zone of peritoneum.   • Internal hernia mostly occurs in epiploic foramen  or opening into the lesser sac or foramen of  Winslow. The loop mostly gets strangulated. It  may also occur in the "paraduodenal fossae".  These are discussed in Chapter 18.   Umbilical hernia: Congenital umbilical hernia: Due  to non-return of midgut loop back to the abdominal  cavity (Fig. 16.29),    Acquired infantile umbilical hernia: Due to weakness  of umbilical scar, a part of the gut may be seen  protruding out. It disappears as the infant grows  (Fig. 16.30),   Paraumbilical hernia : Loop of intestine protrude  through the linea alba around the region of umbilicus  (Fig, 16.31).   Femoral hernia: Occurs more in females, due to  larger pelvis, smaller blood vessels and larger  femoral canal. Its neck lies below and lateral to the  pubic tubercle. Surgery is essential for its treatment  (Fig. 16.32),   Inguinal hernia: Protrusion of the loop of intestine  through the inguinal wall or inguinal canal is called  inguinal hernia (Fig. 16.32).   When the protrusion occurs through the deep  inguinal ring, inguinal canal, superficial inguinal ring  into the scrotum, it is called indirect or oblique inguinal  hernia.   It occurs in male infants, children and has a narrow  neck of the hernial sac.   When the protrusion occurs through the weak  posterior wall of the inguinal canal or triangle of  Hesselbach the hernia is a direct inguinal hernia . It  occurs in much older men and has a wider neck of  hernial sac.   a. Indirect or oblique hernia: Occurs due to partial  or complete patency of the processus vaginalis  (an invagination of the peritoneum). It may  descend into the scrotum.   b. Direct inguinal hernia: Occurs through the  posterior wall of the inguinal canal. It occurs  through Hesselbach's triangle (Fig. 16.34),  bounded by inferior epigastric artery, lateral  border of rectus abdominis and inguinal  ligament. This area is divided into a medial and  lateral parts by the passage of obliterated  umbilical artery.   Epigastric hernia: It occurs through the upper part  of wide linea alba (Fig* 16.36)*   Divarication of recti: Occurs in multiparous female  with weak anterolateral abdominal muscles* Loop  of intestine protrude during coughing/ but returns  back (Fig. 16.36).   Incisional hernia: Occurs through the anterolateral  abdominal wall when some incisions were made for  the surgery/ involving cutting of the spinal nerves.   Lumbar hernia: Occurs through the lumbar triangle  in the posterior part of the abdominal wall. It is  bounded by the iliac crest/ anterior border of  latissimus dorsi and posterior border of external  oblique muscle.   The inguinal hernia peculiarly occurs only in man and  not in any other mammal. This predisposition of man  to hernia is due to the evolutionary changes that have  taken place in the inguinal region as a result of his  upright posture. He has to pay a heavy price for being  upright. The important changes are as follows.   1 The iliac crest has grown forwards into the lower  digitations of external oblique muscle, so that the  inguinal ligament can no more be operated by fleshy  fibres of muscle which now helps in balancing the  body. In all other mammals, external oblique has no  attachment to the iliac crest.   2 The internal oblique and transversus initially  originated from the anterior border of ilium and  the sheath of iliopsoas, and acted as a powerful  sphincter of the inguinal canal. The shift of their  origin to the inguinal ligament and iliac crest has  minimised their role.    3 Due to peculiar growth of hip bones and pelvis, the  crural passage (between hip bone and inguinal  ligament) in man has become much wider than any  other mammal. This predisposes to femoral hernia.   3 nerves: Genital branch of the genitofemoral,  ilioinguinal, autonomic nerves  3 other things: Ductus deferens, pampiniform plexus,  remains of processus vaginalis    • Transpyloric plane is an important landmark in  the abdominal cavity.   * Umbilicus is normally a region of "water shed" for  the lymphatic and venous drainage. It is an  important landmark.   * At umbilicus three systems meet. These are  digestive (vitellointestinal duct), the excretory  (urachus) and vascular (umbilical vessels).   * External oblique is the largest and most superficial  muscle of anterior abdominal wall.   • Internal oblique forms anterior wall, roof and  posterior wall of the inguinal canal. It forms rectus  sheath differently in upper and lower parts of  abdominal wall. It also forms the cremaster muscle  and conjoint tendon.   * Inguinal ligament forms the boundary between  abdomen and lower limb.   * Cremasteric reflex indicates that LI segment of  spinal cord is intact   * Inguinal hernia lies above and medial to pubic  tubercle. Femoral hernia lies below and lateral to  pubic tubercle.   * Femoral hernia is common in females because of  the larger pelvis, bigger femoral canal and smaller  femoral artery.   * Indirect inguinal hernia is more liable to  obstruction as the neck of such a hernia is narrow.   * Paramedian incision in the anterior abdominal  wall is mostly preferred.    In a case of intestinal obstruction an incision is to be  made above the umbilicus.   Ans; The ideal site is a paramedian incision. Though  the median incision is relatively bloodless, it tends  to leave a postoperative weakness through which a  ventral hernia may develop. Paramedian incision  through the rectus sheath are more sound than  median incisions. Rectus abdominis muscles  is retracted laterally to the protect the thoracic nerves.  The nerves enter the rectus muscle from lateral side.    1. The skin around the umbilicus is innervated by one  of the following segments:   2. Which of the following does not contribute to the  formation of the posterior wall of inguinal canal?   3. Which is the most important landmark for  distinguishing inguinal from femoral hernia?   4. Hernia resulting due to non-return of the umbilical  loop of midgut is:   5. Indirect inguinal hernia coming out at the  superficial inguinal ring will have the following  coverings:   6. Which is the covering in all varieties of inguinal  hernia?   10. The plane passing through the body of lumbar 3  vertebra is:   Male genital organs are situated both outside the pelvic  cavity and within the pelvic cavity. As lower  temperature is required for spermatogenesis, the testes  are placed outside the pelvic cavity in the scrotal sac.  Since urethra serves both the functions of urination and  ejaculation, there is only one tube enclosed in the  urogenital triangle.   From the superficial inguinal ring, make a longitudinal  incision downwards through the skin of the anterolateral  aspects of the scrotum till its lower part. Reflect the  skin alone if possible otherwise reflect skin, dartos and  the other layers together till the testis enveloped in its  tunica vaginalis is visualised.   Lift the testis and spermatic cord from the scrotum.  Cut through the spermatic cord at the superficial inguinal  ring and remove it together with the testis and put it in  a tray of water.   Incise and reflect the coverings if any, e.g. remains  of external spermatic fascia, cremaster muscle,  cremasteric fascia and internal spermatic fascia.  Separate the various structures of spermatic cord. Feel  ductus deferens as the important constituent of  spermatic cord. Make a transverse section through the  testis to visualise its interior.   Identify the epididymis capping the superior pole and  lateral surface of the testis. The slit-like sinus of  epididymis formed by tucking-in of the visceral layer of  peritoneum between the testis and the epididymis is  seen on the anterolateral aspect of the testis.   Cut through and reflect the skin along the dorsum of the  penis from the symphysis pubis to the end of the prepuce.   Find the extension of the membranous layer of the  superficial fascia of the abdominal wall on to the penis    (fundiform ligament). The superficial dorsal vein of the  penis lies in the superficial fascia. Trace it proximally to  drain into any of the superficial external pudendal veins  of thigh.   Deep to this vein is the deep fascia and suspensory  ligament of the penis. Divide the deep fascia in the  same line as the skin incision. Reflect it to see the deep  dorsal vein with the dorsal arteries and nerves on each  side.   Make a transverse section through the body of the  penis, but leave the two parts connected by the skin of  urethral surface or ventral surface. Identify two corpora  cavernosa and single corpus spongiosum traversed by  the urethra.   The penis is the male organ of copulation. It is made  up of: (a) A root or attached portion, and (b) a body or  free portion (Fig. 17.1a).   The root of the penis is situated in the superficial perineal  pouch. It is composed of three masses of erectile tissue,  namely the two crura and one bulb. Each crus  (Latin leg) is firmly attached to the margins of the pubic  arch, and is covered by the ischiocavernosus. The bulb  is attached to the perineal membrane in between the  two crura. It is covered by the bulbospongiosus. Its deep    Figs 17.1a and b: Parts of the penis: (a) Ventral view, and (b) sagittal section    surface is pierced (above its centre) by the urethra,  which traverses its substance to reach the corpus  spongiosum (located in the body). This part of the  urethra within the bulb shows a dilatation in its floor,  called the intrabulbar fossa (Fig. 17.1b).   The free portion of the penis is completely enveloped  by skin. It is continuous with the root in front of the  lower part of the pubic symphysis. It is composed of  three elongated masses of erectile tissue. During  erection of the penis these masses become engorged  with blood leading to considerable enlargement. These  masses are the right and left corpora cavernosa, and a  median corpus spongiosum (Fig. 17.2).    The penis has a ventral surface that faces backwards  and downwards, and a dorsal surface that faces  forwards and upwards.   The two corpora cavernosa (Latin hollow) are the  forward continuations of the crura. They are in close  apposition with each other throughout their length. The  corpora cavernosa do not reach the end of the penis.  Each of them terminates under cover of the glans penis  in a blunt conical extremity. They are surrounded by a  strong fibrous envelope called the tunica albuginea. The  tunica albuginea has superficial longitudinal fibres  enclosing both the corpora, and deep circular fibres that  enclose each corpus separately, and also form a median  septum.   The corpus spongiosum is the forward continuation  of the bulb of the penis. Its terminal part is expanded  to form a conical enlargement, called the glans penis.  Throughout its whole length it is traversed by the  urethra. Like the corpora, it is also surrounded by a  fibrous sheath (Fig. 17.2).   The base of the glans (Latin acron) penis has a projecting  margin, the corona (Latin crown) glandis , which overhangs  an obliquely grooved constriction, known as the neck of  the penis. Within the glans the urethra shows a dilatation  (in its roof) called the navicular fossa.   The skin covering the penis is very thin and dark in  colour. It is loosely connected with the fascial sheath of  the organ. At the neck it is folded to form the prepuce  (Latin before penis) or foreskin which covers the glans to  a varying extent and can be retracted backwards to  expose the glans. On the undersurface of the glans there  is a median fold of skin called the frenulum (Latin bridle).   The potential space between the glans and the prepuce  is known as the preputial sac. On the corona glandis and  on the neck of the penis there are numerous small  preputial or sebaceous glands which secrete a sebaceous  material called the smegma , which collects in the  preputial sac (Fig. 17.1a).   The superficial fascia of the penis consists of very loosely  arranged areolar tissue, completely devoid of fat. It may  contain a few muscle fibres. It is continuous with the  membranous layer of superficial fascia of the abdomen  above and of the perineum below. It contains the  superficial dorsal vein of the penis.   The deepest layer of superficial fascia is membranous  and is called the fascia of the penis or deep fascia of penis, or  Buck's fascia. It surrounds all three masses of erectile  tissue, but does not extend into the glans. Deep to it there  are the deep dorsal vein, the dorsal arteries and dorsal  nerves of the penis. Proximally, it is continuous with the  dartos and with the fascia of the urogenital triangle.   a. Th efundiform ligament which extends downwards  from the linea alba and splits to enclose the penis.  It lies superficial to the suspensory ligament (see  Fig. 16.8b).   b. The suspensory ligament lies deep to the fundiform  ligament. It extends from the pubic symphysis and  blends below with the fascia on each side of the  penis.   Near the root of the penis, it passes deep to the  suspensory ligament and through a gap between the  arcuate pubic ligament and anterior margin of perineal  membrane, it divides into right and left branches which  connect below the symphysis pubis with the internal  pudendal veins and ultimately enters the prostatic  plexus.   1 The sensory nerve supply to the penis is derived from  the dorsal nerve of the penis and the ilioinguinal  nerve. The muscles of the root of the penis are  supplied by the perineal branch of the pudendal nerve.   2 The autonomic nerves are derived from the pelvic  plexus via the prostatic plexus. The sympathetic nerves  are vasoconstrictor , and the parasympathetic nerves (S2,  S3, S4) are vasodilator. The autonomic fibres are  distributed through the branches of the pudendal nerve.   Lymphatics from the glans drain into the deep inguinal  nodes also called gland of Cloquet. Lymphatics from  the rest of the penis drain into the superficial inguinal  lymph nodes.   1 The internal pudendal artery gives off three branches  which supply the penis.   a. The deep artery of the penis runs in the corpus  cavernosum. It breaks up into arteries that follow  a spiral course and are, therefore, called helicine  arteries.   b. The dorsal artery of the penis runs on the dorsum,  deep to the deep fascia, and supplies the glans  penis and the distal part of the corpus spongiosum,  the prepuce and the frenulum.   c. The artery of the bulb of the penis supplies the bulb  and the proximal half of the corpus spongiosum.   2 The femoral artery gives off the superficial external  pudendal artery which supplies the skin and fasciae  of the penis.   The dorsal veins, superficial and deep, are unpaired.  Superficial dorsal vein drains the prepuce and penile  skin. It runs back in subcutaneous tissue and inclines  to right or left, before it opens into one of the external  pudendal veins.   Deep dorsal vein lies deep to Buck's fascia. It receives  blood from the glans penis and corpora cavernosa   1 Dilatation of the helicine arteries pours an increased  amount of arterial blood into the cavernous spaces of  the corpora cavernosa. Blood is also poured in small  amount into the corpus spongiosum and into the  glans by their arteries. As the spaces within the  erectile tissue fill up, the penis enlarges.   2 This enlargement presses on the veins preventing  outflow of blood through them. Contraction of the  ischiocavernosus muscles probably has the same  effect.   3 Expansion of the corpora cavernosa, and to a lesser  extent of the corpus spongiosum, stretches the deep  fascia. This restricts enlargement of the penis. Further  flow of blood increases the pressure within the  erectile tissue and leads to rigidity of the penis.   4 Erection is controlled by parasympathetic nerves  (nervi erigentes, S2, S3, S4).   1 Externally, the scrotum is divided into right and left  parts by a ridge or raphe which is continued  forwards on to the undersurface of the penis and  backwards along the middle of the perineum to the  anus (Fig. 17.3).   2 The left half of the scrotum hangs a little lower than  the right, in correspondence with the greater length  of the left spermatic cord.   3 Under the influence of cold, and in young and robust  persons, the scrotum is short, corrugated and closely  applied to the testis. This is due to contraction of the  subcutaneous muscle of scrotum, called the dartos  (Greek skinny). However, under the influence of  warmth, and in old and debilitated persons, the  scrotum is elongated and flaccid due to relaxation  of dartos. From this it appears that the dartos muscle  helps in regulation of temperature within the  scrotum.   Fig. 17.3: Scrotum and penis viewed from below to show the  median raphe   The scrotum is made up of the following layers from  outside inwards (Fig. 17.4).   2 Dartos muscle which replaces the superficial fascia.  The dartos muscle is prolonged into a median vertical  septum between the two halves of the scrotum.   4 The cremasteric (Greek to hang) muscle and fascia  from internal oblique muscle.   The scrotum is supplied by the following arteries:  Superficial external pudendal, deep external pudendal,  scrotal branches of internal pudendal, and cremasteric  branch of inferior epigastric.   The anterior one-third of the scrotum is supplied by  segment LI of the spinal cord through the ilioinguinal  nerve and the genital branch of the genitofemoral nerve  (Fig. 17.5).   The posterior two-thirds of the scrotum are supplied  by segment S3 of the spinal cord through the posterior  scrotal branches of the pudendal nerve, and the perineal  branch of the posterior cutaneous nerve of the thigh. The  areas supplied by segments LI and S3 are separated by  the ventral axial line.   The dartos muscle is supplied by the genital branch  of the genitofemoral nerve.    • Due to laxity of skin and its dependent position,  the scrotum is a common site for oedema. Abundance  of hair and of sebaceous glands also makes it a  site of sebaceous cysts (Fig. 17.6).   • As the scrotum is supplied by widely separated  dermatomes (LI, S3) spinal anaesthesia of the  whole scrotum is difficult to achieve (Fig. 17.5).    • Hydrocoele is a condition in which fluid accumu¬  lates in the processus vaginalis of peritoneum.  Types of hydrocoele are shown in Figs 17.7a to d.   • Tapping a hydrocele is a procedure for removing  the excess fluid from tunica vaginalis. The layers  penetrated by the instrument are:   b. Dartos muscle and membranous layer of  superficial fascia (Fig. 17.4).   The testis is the male gonad. It is homologous with the  ovary of the female.   It is suspended in the scrotum by the spermatic cord.  It lies obliquely, so that its upper pole is tilted forwards  and medially. The left testis is slightly lower shape and  size than the right.   The testis is oval in shape, and is compressed from  side to side. It is 3.75 cm long, 2.5 cm broad from before  backwards, and 1.8 cm thick from side to side. An adult  testis weighs about 10 to 15 g.   Figs 17.7a to d: Types of hydrocoele: (a) Vaginal, (b) infantile,  (c) congenital, and (d) encysted   Inferior aberrant ductules  Fig. 17.8: Lateral view of the right testis and surrounding  structures with the embryonic remnants present in the region   The upper and lower poles are convex and smooth. The  upper pole provides attachment to the spermatic cord.   The anterior border is convex and smooth, and is fully  covered by the tunica vaginalis. The posterior border is  straight, and is only partially covered by the tunica  vaginalis. The epididymis lies along the lateral part of  the posterior border. The lateral part of the epididymis  is separated from the testis by an extension of the cavity  of the tunica vaginalis. This extension is called the sinus  of epididymis (Figs 17.9 and 17.10).    posteriorly where the testicular vessels and nerves enter  the gland. The posterior border of the tunica albuginea  is thickened to form an incomplete vertical septum,  called the mediastinum testis , which is wider above than  below. Numerous septa extend from the mediastinum  to the inner surface of the tunica albuginea. They  incompletely divide the testis into 200 to 300 lobules.   The tunica vasculosa is the innermost, vascular coat  of the testis lining its lobules.   Attached to the upper pole of the testis, there is a  small oval body called the appendix of the testis. It is a  remnant of the paramesonephric duct.   The testis is covered by layers of the scrotum. In  addition it is also covered by three coats. From outside  inwards, these are the tunica (Latin cover) vaginalis , the  tunica albuginea and the tunica vasculosa (Fig. 17.8).   The tunica vaginalis (Latin sheath) represents the lower  persistent portion of the processus vaginalis. It is  invaginated by the testis from behind and, therefore,  has a parietal and a visceral layer with a cavity in  between. It covers the whole testis, except for its  posterior border.   The tunica albuginea (Latin white) is a dense, white  fibrous coat covering the testis all around. It is covered  by the visceral layer of the tunica vaginalis, except    The glandular part of the testis consists of 200 to 300  lobules. Each lobule contains two to three seminiferous  tubules. Each tubule is highly coiled on itself. When  stretched out, each tubule measures about 60 cm in  length, and is about 0.2 mm in diameter. The tubules  are lined by cells which represent stages in the  formation of spermatozoa.   The seminiferous tubules join together at the apices of  the lobules to form 20 to 30 straight tubules which enter  the mediastinum (Fig. 17.9). Here they anastomose with  each other to form a network of tubules, called the rete  testis. In its turn, the rete testis gives rise to 12 to 30  efferent ductules which emerge near the upper pole of  the testis and enter the epididymis. Here each tubule  becomes highly coiled and forms a lobe of the head of  the epididymis. The tubules end in a single duct which  is coiled on itself to form the body and tail of the  epididymis. It is continuous with the ductus deferens.   The testicular artery is a branch of the abdominal aorta  given off at the level of vertebra L2. It descends on the   posterior abdominal wall to reach the deep inguinal  ring where it enters the spermatic cord. At the posterior  border of the testis, it divides into branches. Some small  branches enter the posterior border, while larger  branches; medial and lateral, pierce the tunica albuginea  and run on the surface of the testis to ramify in the  tunica vasculosa (Fig. 17.9).   The veins emerging from the testis form the pampiniform  plexus (pampiniform = like a vine). The anterior part of  the plexus is arranged around the testicular artery, the  middle part around the ductus deferens and its artery,  and the posterior part is isolated. The plexus condenses  into four veins at the superficial inguinal ring, and into  two veins at the deep inguinal ring. These veins  accompany the testicular artery. Ultimately one vein is  formed which drains into the inferior vena cava on the  right side, and into the left renal vein on the left side  (Fig. 17.11).   The lymphatics from the testis ascend along the  testicular vessels and drain into the preaortic and para¬  aortic groups of lymph nodes at the level of second  lumbar vertebra (Fig. 17.11).   The testis is supplied by sympathetic nerves arising  from segment T10 of the spinal cord. They pass through  the renal and aortic plexuses. The nerves are both  afferent for testicular sensation and efferent to the blood  vessels (vasomotor).   The seminiferous tubule consists of cells arranged in  4-8 layers in fully functioning testis. These cells are of  two types, namely:   primary spermatocytes, secondary spermatocytes,  spermatids and spermatozoa. The cells of Sertoli are  tall and columnar in shape extending from the basal  lamina to the central lumen. They support and protect  the developing germ cells and help in maturation of  spermatozoa. Spermatogenesis is controlled by follicle  stimulating hormone (FSH) of the anterior pituitary  gland.   Interstitial cells or cells of Ley dig are found as small  clusters in between the seminiferous tubules. They  secrete testosterone/androgen (I make man). The  activity of Leydig cells is controlled by interstitial cell  stimulating hormone (ICSH) of the anterior pituitary  gland.   ■ Undescended testis or cryptorchidism: The organ may  lie in the lumbar, iliac, inguinal, or upper scrotal  region (Fig. 17.12). The important features of an  undescended testis are as follows.   c. A malignant tumour is more prone to develop  in it.   • Ectopic testis : The testis may occupy an abnormal  position due to deviation from the normal route  of descent It may be under the skin of the lower  part of the abdomen, under the skin of the front  of the thigh, in the femoral canal, under the skin  of the penis, and in the perineum behind the  scrotum (Fig. 17.13). The important features of an  ectopic testis are as follows.   c. It may be divorced from the epididymis which  may lie in the scrotum.   • Hermaphroditism or intersex is a condition in which  an individual shows some features of a male and  some of a female. In true hermaphroditism, both  testis and ovary are present. In pseudoherma¬  phroditism, the gonad is of one sex while the  external or internal genitalia are of the opposite  sex.   • The testis and epididymis may be the site of  various infections and of tumours.   • Testis may be palpated to check any nodules, or  any irregularity or size or consistency.   • Varicocoele is produced by dilatation of the  pampiniform plexus on veins (Fig. 17.14). It is  usually left-sided; possibly because the left  testicular vein is longer than the right, enters the  left renal vein at a right angle and is crossed by  the colon which may compress it when loaded.   Fig. 17.13: Positions of ectopic testis: 1. Lower part of  abdomen, 2. front of thigh, 3. femoral canal, 4. skin of penis,  and 5. behind the scrotum   The epididymis is an organ made up of highly coiled  tube that act as reservoir of spermatozoa.   Parts: Its upper end is called the head . The head is  enlarged and is connected to the upper pole of the testis  by efferent ductules. The middle part is called the body.  The lower part is called the tail. The head is made up of  highly coiled efferent ductules. The body and tail are  made up of a single duct, the duct of the epididymis which  is highly coiled on itself. At the lower end of the tail  this duct becomes continuous with the ductus deferens  (Latin conducing away) (Figs 17.9 and 17.10).   The epididymis is supplied by the testicular artery  through a branch which anastomoses with and  reinforces the tiny artery to the ductus deferens. The  venous and lymphatic drainage are similar to those of  the testis. Like the testis the epididymis is supplied by  sympathetic nerves through the testicular plexus, the  fibres of which are derived from segments Til to LI of  the spinal cord.   The tubules of epididymis are lined by pseudostratified  columnar epithelium with stereocilia. The tubules are  surrounded by connective tissue.    The common causes of epididymitis and epididymo-  orchitis are tuberculosis, filariasis, the gonococcal  and other pyogenic infections.   It is comprised of spermatogenic cells, cells of Sertoli  and Leydig's cells.   Spermatogenic series of cells are derived from  endoderm of dorsocaudal part of yolk sac, i.e.  endoderm.   Cells of Sertoli are derived from epithelial cells, i.e.  coelomic epithelium.   Leydig's cells: Mesodermal in origin. There is thick  tunica albuginea in the testis and the medulla portion  of developing gland predominates.   • The testes develop in relation to the developing  mesonephros, at the level of segments T10 to T12.    Figs 17.15a to d: Stages of descent of testis include formation of processus vaginalis    • Subsequently, they descend to reach the scrotum  (Fig. 17.15). Each testis begins to descend during the  second month of intrauterine life.   • Rests at the deep inguinal ring from the 4th to the  6th month,   • And the bottom of the scrotum by the 9th month.   • An extension of peritoneal cavity called the processus  vaginalis precedes the descent of testis into the  scrotum, into which the testis invaginates. The  processus vaginalis closes above the testis. Descent  does not occur after one year of age.   a. Hormones including the male sex hormone  produced by the testis, and maternal gonadotro¬  pins.   c. Formation of the gubernaculum: This is a band of  loose tissue extending from the lower pole of the  testis to the scrotum. The gubernaculum helps in  the descent of the testis. The remaining part of  gubernaculum after the descent of testis is known  as ligament of scrotum.   d. Intra-abdominal temperature and intra-abdominal  pressure may have something to do with descent  of the testis.   1 The predominant duct in males is the medially  placed mesonephric or Wolffian duct. Distally, it  opens into the primitive urogenital sinus. Its  development and differentiation is affected by  Mullerian inhibiting substance , testosterone and  dihydrotestosterone.   3 Mesonephric tubules form functional rete testis and  vestigeal paradidymis and aberrant ductules.   As early as 3rd week of development, the mesenchymal  cells from primitive streak migrate around the cloacal  membrane. These form raised cloacal folds. Cranially the  folds fuse to form genital tubercle.   During 6th week of development cloacal folds  are divided into urethral folds anteriorly and anal folds  posteriorly. Lateral to urethral folds a pair of swellings,  the genital swellings appear.   Genital swellings form the scrotum. Genital tubercle  elongates to form the phallus . Urethral folds get pulled   forwards to form lateral wall of urethral groove  extending on inferior aspect of phallus. Lining of groove  forms urethral plate and is endodermal in origin.  Urethral folds close over the urethral plate to form most  of the penile urethra.   Urethra in the glans penis is formed by invagination  of ectodermal cells into the glans. The ectodermal urethra  gets continuous with the endodermal urethra.   These are as follows (Fig. 17.8). Their importance is that  they may sometimes form cysts:   1 The appendix of the testis or pedunculated hydatid of  Morgagni.   2 The appendix of the epididymis is a small rounded  pedunculated body attached to the head of the  epididymis. It represents the cranial end of the  mesonephric duct.   3 The superior aberrant ductules are attached to the testis  cranial to the efferent ductules. They represent the  upper mesonephric tubules.   4 The inferior aberrant ductules, one or two, are attached  to the tail of the epididymis, and represent the  intermediate mesonephric tubules. One of them  which is more constant may be as long as 25 cm.   5 The paradidymis or organ of Giraldes consists of free  tubules lying in the spermatic cord above the head  of the epididymis. They are neither connected to the  testis nor to the epididymis, and represent the caudal  mesonephric tubules.    * The cavernous tissue is finer in corpus spongiosum  as it contains urethra.   * Penis is supplied by deep, dorsal arteries, artery to  the bulb and superficial external pudendal artery.   * Tunica vaginalis is the lower persistent part of  processes vaginalis, an extension of peritoneal  cavity.   * Right testicular vein drains into inferior vena cava.  Left testicular vein drains into left renal vein.   * Lymph node of Cloquet is involved in cancer of  the penis. Varicocoele is common on left side.   * Hydrocele is the commonest cause of swelling of  the scrotum.    A premature male infant was brought to the hospital.  His mother complained of empty right scrotal sac  and a swelling in right inguinal region.   • What are the time events of the descent of testis?   Ans: Since the child is premature, the testis has not  descended on right side. The mass in the right  inguinal region is the testis only. It will descend  down on its own within few months.   Testis begins to descend during 2nd month of  intrauterine life -^reaches iliac fossa (3rd month)  reaches inguinal canal in 7th month, comes down to  superficial inguinal ring during 8th month and  reaches scrotum during 9th month.    1. Testis is supplied by sympathetic nerves from one  of the following segments.   3. A needle pierces all the structures to drain  hydrocele of testis except:   5. Fascia transversalis of abdominal wall forms one  of the following coverings of testis.   Abdominal cavity is the largest cavity. It encloses the  peritoneal cavity between its parietal and visceral  layers. Parietal layer clings to the wall of parieties while  visceral layer is intimately adherent to viscera  concerned. So their vascular supply and nerve supply  are same as the parieties and viscera respectively.   There are very lengthy organs in the peritoneal  cavity. These had to be disciplined with limited  movements for proper functioning of the gut in  particular and the body in general. Infections involving  the parietal peritoneum impart protective "board-like  rigidity" to the abdominal wall. Referred pain from the  viscera to a distant area is due to somatic and  sympathetic nerves reaching the same spinal segment.   For the purpose of describing the location of viscera,  the abdomen is divided into nine regions by four  imaginary planes, two horizontal and two vertical. The  horizontal planes are the transpyloric and  transtubercular planes. The vertical planes are the right  lateral and the left lateral planes (Fig. 18.1).   The transpyloric plane of Addison passes midway  between the suprasternal notch and the pubic    symphysis. It lies roughly a hand's breadth below  the xiphisternal joint. Anteriorly, it passes through  the tips of the ninth costal cartilage; and posteriorly  through the body of vertebra LI near its lower border.  Organs present on this plane are pylorus of stomach  beginning of duodenum, neck of pancreas and hila of  the kidneys.   The transtubercular plane passes through the tubercles  of the iliac crest and the body of vertebra L5 near its  upper border.   The right and left lateral planes correspond to the  midclavicular or mammary lines. Each of these vertical  planes passes through the midinguinal point and  crosses the tip of the ninth costal cartilage.   The nine regions marked out in this way are arranged  in three vertical zones, median, right and left. From  above downwards, the median regions are epigastric,  umbilical and hypogastric . The right and left regions, in  the same order, are hypochondriac , lumbar and iliac .   Position of many organs is mentioned in Table 18.1.  Liver chiefly occupies the right hypochondrium.  Stomach and spleen occupy the left hypochondrium.  Duodenum lies in relation to posterior abdominal wall.  Coils of jejunum and ileum fill up the umbilical, lumbar  and iliac regions.   Large intestine lies at the periphery of abdominal  cavity, caecum, ascending colon on right side, descen¬  ding colon on left side and transverse colon across the  cavity (Fig. 18.7).   The peritoneum (Greek stretched over) is a large serous  membrane lining the abdominal cavity. Histologically,  it is composed of an outer layer of fibrous tissue, which  gives strength to the membrane and an inner layer of  mesothelial cells which secrete a serous fluid which  lubricates the surface, thus allowing free movements  of viscera.    The peritoneum is in the form of a closed sac which  is invaginated by a number of viscera. As a result the  peritoneum is divided into:   The peritoneum which is a simple cavity, before  being invaginated by viscera becomes highly compli¬  cated (Fig. 18.2).    2 Embryologically, it is derived from the somato-  pleuric layer of the lateral plate mesoderm.   3 Its blood supply and nerve supply are the same as  those of the overlying body wall. Because of the  somatic innervation, parietal peritoneum is pain  sensitive.   1 It lines the outer surface of the viscera, to which it is  firmly adherent and cannot be stripped. In fact it  forms a part and parcel of the viscera.   2 Embryologically, it is derived from the splanchno-  pleuric layer of the lateral plate mesoderm.   3 Its blood supply and nerve supply are the same as  those of the underlying viscera. Because of the  autonomic innervation, visceral peritoneum evokes  pain when viscera is stretched, ischaemic or  distended.   1 Many organs within the abdomen are suspended by  folds of peritoneum. Such organs are mobile. The  degree and direction of mobility are governed by  the size and direction of the peritoneal fold. Other  organs are fixed and immobile. They rest directly on  the posterior abdominal wall, and may be covered  by peritoneum on one side. Such organs are said to  be retroperitoneal (Table 18.2). Some organs are    Fig. 18.2: Diagrammatic transverse section of the abdomen  showing the arrangement of the peritoneum. The peritoneal  cavity is actually a potential space and not so spacious as shown   1 It lines the inner surface of the abdominal and pelvic  walls and the lower surface of the diaphragm. It  is loosely attached to the walls by extraperitoneal  connective tissue and can, therefore, be easily  stripped.    Fig. 18.3: Scheme to show how a loop of gut may lose its  mesentery   suspended by peritoneal folds in early embryonic  life, but later become retroperitoneal (Fig. 18.3).   2 Apart from allowing mobility, the peritoneal folds  provide pathways for passage of vessels, nerves and  lymphatics.   a. In general, the name of the fold is made up of the  prefix 'rues' or 'meso' followed by the name of the  organ, e.g. the fold suspending the small intestine  or enteron is called the mesentery ; and a fold  suspending part of the colon is called mesocolon.   b. Large peritoneal folds attached to the stomach are  called omenta; singular of which is omentum which  means cover.   c. In many situations, double-layered folds of  peritoneum connect organs to the abdominal wall  or to each other. Such folds are called ligaments.  These may be named after the structures they  connect. For example, the gastrosplenic ligament  connects the stomach to the spleen. Other folds  are named according to their shape, e.g. the  triangular ligaments of the liver.   Some of the larger peritoneal folds are considered in  this chapter, while others are considered along with  the organs concerned.   The viscera which invaginate the peritoneal cavity  completely fill it so that the cavity is reduced to a  potential space separating adjacent layers of peritoneum.  Between these layers there is a thin film of serous fluid  secreted by the mesothelial cells. This fluid performs a  lubricating function and allows free movement of one  peritoneal surface over another. Under abnormal  circumstances there may be collection of fluid called  ascites, or of blood called haemoperitoneum , or of air  called pneumoperitoneum within the peritoneal cavity.   The peritoneal cavity is divided broadly into two  parts. The main, larger part is known as the greater sac ,  and the smaller part, situated behind the stomach, the  lesser omentum and the liver, is known as the omental  bursa or lesser sac. The two sacs communicate with each  other through the epiploic foramen or foramen of Winslow  or opening into the lesser sac.   Small pockets or recesses of the peritoneal cavity may  be separated from the main cavity by small folds of  peritoneum. These peritoneal recesses or fossae are of  clinical importance. Internal hernia may take place into  these recesses.   In the male, the peritoneum is a closed sac lined by  mesothelium or flattened epithelium. The female  peritoneum has the following distinguishing features.    1 The peritoneal cavity communicates with the exterior  through the uterine tubes.   2 The peritoneum covering the ovaries is lined by  cubical epithelium.   3 The peritoneum covering the fimbria is lined by  columnar ciliated epithelium.   1 Movements of viscera: The chief function of the  peritoneum is to provide a slippery surface for free  movements of abdominal viscera. This permits  peristaltic movements of the stomach and intestine,  abdominal movements during respiration and  periodic changes in the capacity of hollow viscera  associated with their filling and evacuation. The  efficiency of the intestines is greatly increased as a  result of the wide range of mobility that is possible  because the intestines are suspended by large folds  of peritoneum.   2 Protection of viscera: The peritoneum contains various  phagocytic cells which guard against infection.  Lymphocytes present in normal peritoneal fluid  provide both cellular and humoral immunological  defence mechanisms. The greater omentum has the  power to move towards sites of infection and to seal  them thus preventing spread of infection. For this  reason the greater omentum is often designated as  the "policeman of the abdomen".   3 Absorption and dialysis: The mesothelium acts as a  semipermeable membrane across which fluids and  small molecules of various solutes can pass. Thus,  the peritoneum can absorb fluid effusions from the  peritoneal cavity. Water and crystalloids are  absorbed directly into the blood capillaries, whereas  colloids pass into lymphatics with the aid of  phagocytes. The greater absorptive power of the  upper abdomen or subphrenic area is due to its larger  surface area and because respiratory movements aid  absorption.   Therapeutically, considerable volumes of fluid can  be administered through the peritoneal route.  Conversely, metabolites, like urea can be removed  from the blood by artificially circulating fluid  through the peritoneal cavity. This procedure is  called peritoneal dialysis.   4 Healing poioer and adhesions: The mesothelial cells of  the peritoneum can transform into fibroblasts which  promote healing of wounds. They may also form  abnormal adhesions causing obstruction in hollow  organs.   5 Storage of fat: Peritoneal folds are capable of storing  large amounts of fat, particularly in obese persons.    • Collection of free fluid in the peritoneal cavity is  known as ascites. Common causes of ascites are  cirrhosis of the liver, tubercular peritonitis,  congestive heart failure, and malignant infiltration  of the peritoneum. Veins also get prominent in  cirrhosis of liver.   • Fluid from the (peritoneal cavity) may be removed  by puncturing the abdominal wall either in the  median plane midway between the umbilicus and  pubic symphysis, or at a point just above the  anterior superior iliac spine. The procedure is  called paracentesis. Urinary bladder must be  emptied before the procedure (Fig. 18.4).   • Inflammation of the peritoneum is called  peritonitis. It may be localized when a subjacent  organ is infected; or maybe generalized. The latter  is a very serious condition.   • The presence of air in the peritoneal cavity is called  pneumoperitoneum . It may occur after perforation  of the stomach or intestines.   • Laparoscopy is the examination of the peritoneal  cavity under direct vision using an instrument  called laparoscope.   • Opening up the abdominal cavity by a surgeon is  called laparotomy.   • Greater omentum limits the spread of infection by  sealing off the site of ruptured vermiform appendix  or gastric ulcer and tries to delay the onset of  peritonitis. It is called "abdominal policeman",   • Inflammation of parietal peritoneum causes  localized severe pain and rebound tenderness on  removing the fingers.   • Peritoneal dialysis is done in case of renal failure.  The procedure removes the urea, etc. as it diffuses  through blood vessels into the peritoneal cavity.   Expose the extensive abdominal cavity by reflecting  anterior abdominal wall into four flaps, two (right and  left) above and two below the umbilicus.   Identify the peritoneum. Divide and reflect it with the  anterior abdominal wall. Cut the fold of peritoneum  which passes from the median part of the supra-  umbilical part of the anterior abdominal wall to the liver  known as the falciform ligament. This fold contains the  ligamentum teres of the liver or the obliterated left  umbilical vein in its free posterior border.   Examine the posterior surface of the reflected lower  parts of anterior abdominal wall. Identify five ill-defined  peritoneal folds which pass upwards (Fig. 18.19) towards  the umbilicus. These are two lateral, two medial and one  median umbilical folds.   Identify the parietal peritoneum, adherent to the  parieties or walls of the abdominal cavity. Trace it from  the walls to form various double layered folds which  spread out to enclose the viscera as the visceral  peritoneum.   Identify and lift up the greater omentum. See its  continuity with the stomach above and the transverse  colon fused with its posterior surface a short distance  inferior to the stomach.   Cut through the anterior layers of the greater  omentum 2-3 cm inferior to the arteries to open the  lower part of the omental bursa sufficiently to admit a  hand. Explore the bursa.   Pull the liver superiorly and lift its inferior margin  anteriorly to expose the lesser omentum. Examine the  right free margin of lesser omentum, containing the bile  duct, proper hepatic artery and portal vein. This free  margin forms the anterior boundary of the opening into  the lesser sac, i.e. epiploic foramen. The posterior  boundary is the inferior vena cava. Superior to opening  into the lesser sac is the caudate process of liver and  inferiorly is the first part of duodenum.   Remove the anterior layer of peritoneum from the  lesser omentum along the lesser curvature of the  stomach. Find and trace the left gastric vessels along  the lesser curvature of stomach. Trace the oesophageal  branches to the oesophagus.   Trace the right gastric artery to the proper hepatic  artery and the vein to the portal vein. Expose the proper  hepatic artery and trace its branches to the porta  hepatis.   Trace the cystic duct from the gallbladder. Follow  the common hepatic duct to the porta hepatis and the  bile duct till it passes posterior to the duodenum.   The folds can be best understood by recapitulating the  embryology of the gut. The developing gut is divisible  into three parts, foregut, midgut and hindgut. Each part  has its own artery which is a ventral branch of the  abdominal aorta. The coeliac artery supplies the  foregut; the superior mesenteric artery supplies the  midgut; and the inferior mesenteric artery supplies the  hindgut (Fig. 18.5).    Apart from some other structures th e foregut forms  the oesophagus, the stomach, and the upper part of the  duodenum up to the opening of the bile duct. The  midgut forms the rest of the duodenum, the jejunum,  the ileum, the appendix, the caecum, the ascending  colon, and the right two-thirds of the transverse colon.  The hindgut forms the left one-third of the transverse  colon, the descending colon, the sigmoid colon,  proximal part of the rectum. The anorectal canal forms  distal part of rectum and the upper part of the anal canal  up to the pectinate line.   The abdominal part of the foregut is suspended by  mesenteries both ventrally and dorsally. The ventral  mesentery of the foregut is called the ventral  mesogastrium , and the dorsal mesentery is called dorsal  mesogastrium (gastrium means stomach) (Fig. 18.6).   The ventral mesogastrium becomes divided by the  developing liver into a ventral part and a dorsal part.  The ventral part forms the ligaments of the liver,  namely:   The dorsal part of the ventral mesogastrium forms  the lesser omentum.    Fig. 18.6: Transverse section through the embryonic foregut  showing the ventral and dorsal mesogastria and their divisions   a. The greater or caudal part of the dorsal  mesogastrium becomes greatly elongated and  forms the greater omentum.   b. The spleen develops in relation to the cranial part  of the dorsal mesogastrium, and divides it into  dorsal and ventral parts. The ventral part forms  the gastrosplenic ligament while the dorsal part  forms the lienorenal ligament.   c. The cranial most part of the dorsal mesogastrium  forms the gastrophrenic ligament.   The midgut and hindgut have only a dorsal mesentery,  which forms the mesentery of jejunum and ileum, the  mesoappendix, the transverse mesocolon and the  sigmoid mesocolon. The mesenteries of the duodenum,  the ascending colon, the descending colon and the  rectum are lost during development (Fig. 18.7).    Fig. 18.7: Diaphragm, liver, stomach and spleen in position.  Anterior view of the small and large intestines showing the parts of  the dorsal mesentery that persist and other parts which are absorbed   The greater omentum (Latin apron) is a large fold of  peritoneum which hangs down from the greater  curvature of the stomach like an apron and covers the  loops of intestines to a varying extent. It is made up of  four layers of peritoneum all of which are fused together  to form a thin fenestrated membrane containing  variable quantities of fat and small arteries and veins  (Figs 18.8 and 18.9).    upon themselves to form the posterior two layers which  ascend to the anterior surface of the head, and the  anterior border of the body of the pancreas. The folding  of the omentum is such that the first layer becomes the  fourth layer and the second layer becomes the third  layer. In its upper part, the fourth layer is partially fused  to the anterior surface of the transverse colon and of  the transverse mesocolon. The part of the peritoneal  cavity called the lesser sac between the second and third  layers gets obliterated, except for about 2.5 cm below  the greater curvature of the stomach.    The anterior two layers descend from the greater  curvature of the stomach to a variable extent, and fold    Fig. 18.8: Anterior view of the peritoneal folds attached to the  greater and lesser curvatures of the stomach    Fig. 18.9: Left view of a sagittal section of the abdomen showing  the greater and lesser omenta and the transverse mesocolon    1 The right and left gastroepiploic vessels anastomose  with each other in the interval between the first two  layers of the greater omentum a little below the  greater curvature of the stomach.   2 It protects the peritoneal cavity against infection  because of the presence of macrophages in it.  Collections of macrophages form small, dense  patches, known as milky spots , which are visible to  the naked eye.   3 It also limits the spread of infection by moving to the  site of infection and sealing it off from the surrounding  areas. On this account, the greater omentum is also  known as the policeman of the abdomen.   Remove the remains of the lesser omentum leaving  the vessels and duct intact and examine the abdominal  wall posterior to the omentum and the omental bursa.   Turn the small intestine to the left. Cut through the  right layer of peritoneum of the mesentery along the  line of its attachment to the posterior abdominal wall  and strip it from the mesentery. Remove the fat from  the mesentery to expose the superior mesenteric  vessels in its root and their branches and tributaries in  the mesentery.   Trace the superior mesenteric vessels proximally and  distally. Dissect the branches to the jejunum, ileum,  caecum, appendix, ascending colon, right two-thirds of  transverse colon, the distal part of duodenum and  pancreas.   Turn the small intestine and its mesentery to the right.  Remove the peritoneum and fat on the posterior  abdominal wall between the mesentery and descending  colon to expose the inferior mesenteric vessels and the  autonomic nerves and lymph nodes associated with  them.   Turn the caecum upwards and uncover the structures  posterior to it. Trace the three taeniae on the external  surface of the colon and cranial to the root of the  vermiform appendix.   This is a fold of peritoneum which extends from the  lesser curvature of the stomach and the first 2 cm of  the duodenum to the liver. The portion of the lesser  omentum between the stomach and the liver is called  the hepatogastric ligament , and the portion between the  duodenum and the liver is called the hepatoduodenal  ligament . Behind the lesser omentum there lies a part of  the lesser sac. The lesser omentum has a free right  margin behind which there is the epiploic foramen. The  greater and lesser sacs communicate through this  foramen.   Inferiorly, the lesser omentum is attached to the lesser  curvature of the stomach and to the upper border of  the first 2 cm of the duodenum. Superiorly, it is attached  to the liver, the line of attachment being in the form of  an inverted 'L'. The vertical limb of the '1/ is attached  to the bottom of the fissure for the ligamentum    venosum, and the horizontal limb to the margins of the  porta hepatis (Fig. 18.10).   5 The hepatic plexus of nerves, all enclosed in a  perivascular fibrous sheath.   Along the lesser curvature of the stomach and along  the upper border of the adjoining part of the duodenum  it contains:   The mesentery (Greek fold of intestine) of the small  intestine or mesentery proper is a broad, fan-shaped  fold of peritoneum which suspends the coils of jejunum  and ileum from the posterior abdominal wall (Fig. 18.11).   The attached border , or root of the mesentery , is 15 cm long,  and is directed obliquely downwards and to the right.  It extends from the duodenojejunal flexure on the left  side of vertebra L2 to the upper part of right sacroiliac  joint. It crosses the following structures:    Quadrate lobe  Gallbladder  Porta hepatis  Right lobe of liver  Inferior vena cava  Bare area  Portal vein  Bile duct    Fig. 18.10: The attachments and contents of the lesser omentum. The liver has been turned upwards so that its posteroinferior  surface can be seen   1 The third part of the duodenum where the superior  mesenteric vessels enter into it;   The free or intestinal border is 6 metres long, and is  thrown into pleats (Fig. 18.11). It is attached to the gut,  forming its visceral peritoneum or serous coat.   It is a small, triangular fold of peritoneum which  suspends the vermiform appendix from the posterior  surface of the lower end of the mesentery close to the  ileocaecal junction. Usually the fold extends up to the  tip of the appendix, but sometimes it fails to reach the  distal one-third or so. It contains vessels, nerves, lymph  nodes and lymphatics of the appendix (Fig. 18.12).   Fig. 18.12: The attachment of the mesoappendix to the posterior  (left) surface of the lower end of the mesentery    The breadth of the mesentery is maximum and is about  20 cm in the central part, but gradually diminishes  towards both the ends.   Fat is most abundant in the lower part of the mesentery,  extending from the root to the intestinal border. The  upper part of the mesentery contains less fat, which  tends to accumulate near the root. Near the intestinal  border it leaves oval or circular fat free, translucent  areas, or windows.   Expose the anterior border of the pancreas and define  the attachments of the transverse mesocolon. Trace  the duodenum from the pylorus to the duodenojejunal  flexure.   This is a broad fold of peritoneum which suspends the  transverse colon from the upper part of the posterior  abdominal wall (Figs 18.7 and 18.9).   The root of the transverse mesocolon is attached to the  anterior surface of the head, and the anterior border of  the body of the pancreas. The line of attachment is  horizontal with an upward inclination towards the left  (Fig. 18.13).   It contains the middle colic vessels; the nerves, lymph  nodes and lymphatics of the transverse colon.   Trace the fold of peritoneum from the upper half of left  external iliac artery to the termination of left common iliac  artery and then downwards till the third piece of sacrum.   This is a triangular (Greek 'S' shape) fold of peritoneum  which suspends the sigmoid colon from the pelvic wall  (Fig. 18.7).   The root is shaped like an inverted 'V'. Its apex lies  over the left ureter at the termination of the left common  iliac artery. The left limb of 'V' is attached along the  upper half of the left external iliac artery; and the right  limb to the posterior pelvic wall extending downwards  and medially from the apex to the median plane at the  level of vertebra S3 (Fig. 18.14).   The sigmoid vessels in the left limb; superior rectal  vessels, nerves, lymph nodes and lymphatics in the  right limb of the sigmoid colon.    From Fig. 18.15 it can be seen that on reaching the liver,  the peritoneum forming the two layers of the lesser  omentum passes on to the surface of the liver. After  lining the surfaces of the liver this peritoneum is  reflected on to the diaphragm and to the anterior  abdominal wall in the form of a number of ligaments.  These are the falciform ligament, the left triangular  ligament, the coronary ligaments and the right  triangular ligament. The falciform ligament is described  below. The other ligaments are described later along  with the liver.   The falciform ligament is a sickle-shaped fold of  peritoneum which connects the anterosuperior surface  of the liver to the anterior abdominal wall and to the  undersurface of the diaphragm. This fold is raised by  the ligamentum teres of the liver. The ligamentum teres  extends from the umbilicus to the inferior border and  inferior surface of the liver. It joins the left branch of    Superior layer of coronary ligament  The bare area of liver  Right triangular ligament  Inferior layer of coronary ligament  Right lobe of liver    Fig. 18.15: Reflections of peritoneum on the liver. Superior and posterior aspect    the portal vein (at the left end of the porta hepatis) to  the ligamentum venosum (Fig. 18.16).   The layout of the greater sac can be studied by tracing  the peritoneum both vertically and horizontally.   1 Peritoneum lining the anterior abdominal wall and  diaphragm, layer 1st.   2 Peritoneum lining upper part of posterior  abdominal wall and diaphragm, layer 3rd.   3 Layers 1st and 2nd enclose most of the liver. The  two layers get reflected at porta hepatis to form the  lesser omentum.   4 Lesser omentum encloses the stomach and two  layers pass downwards as greater omentum, where  these fold upon themselves. First layer becomes  fourth layer and second layer becomes the third  layer.   5 Third and fourth layers enclose transverse colon to  continue as transverse mesocolon.   6 Third layer lines the structures in the upper part of  posterior abdominal wall.   7 The fourth layer passes around the small intestine  to form the mesentery of small intestine.   8 Peritoneum lines the structures in the posterior  abdominal wall and descends into the true pelvis  in front of the rectum. The subsequent tracing is  different in the male and in the female.   9 In the male (Fig. 18.17a), the peritoneum passes  from the front of rectum to the urinary bladder,  forming rectovesical pouch.   10 In the female, it passes from the front of rectum to  the uterus forming rectouterine pouch and from  the uterus to the urinary bladder forming the  vesicouterine pouch (Fig. 18.17b).    Figs 18.17a and b: (a) Sagittal section through the abdomen  (male) to show the reflections of peritoneum, and (b) sagittal  section through a female pelvis showing the peritoneal reflections    Both in the male and female the peritoneum passes  from the urinary bladder to the anterior abdominal  wall, thus completing the sagittal tracing of the  peritoneum.   In Fig. 18.17a note that the lesser sac is bounded in  front by:   c. First and second layers of greater omentum.  Lesser sac is bounded behind by third and fourth   layers of the greater omentum and the peritoneum  lining the upper part of the posterior abdominal wall.   Falciform ligament from the anterior abdominal wall  encloses the liver. At porta hepatis it forms lesser  omentum which encloses the stomach. The two layers  pass to left towards spleen as gastrosplenic ligament. At  the hilum, the two layers of gastrosplenic ligament   diverge. The anterior layer encloses the spleen, forms  one layer of lienorenal ligament, covers left kidney and  continues to line the structures in the anterior  abdominal wall (Fig. 18.18). The posterior layer forms  the other layer of lienorenal ligament and lines the  structures in the posterior abdominal wall. The two  layers get reflected as falciform ligament on the liver.   On the back of the anterior abdominal wall we see a  number of peritoneal folds, and fossae (Fig. 18.19).  Starting from the median plane these are:   1 The median umbilical fold raised by the median  umbilical ligament (remnant of the urachus).   3 The medial umbilical fold raised by the obliterated  umbilical artery.   5 The lateral umbilical fold raised by the inferior  epigastric vessels.   6 The femoral fossa overlying the femoral septum.  Further laterally the peritoneum passes over the   lateral part of abdominal wall to reach the posterior  abdominal wall. Near the middle, the peritoneum  becomes continuous with the two layers of the  mesentery and thus reaches the small intestine.   At this level we also see the greater omentum made  up of four layers. It lies between the intestines and the  anterior abdominal wall.    Fig. 18.18: Horizontal section through the supracolic compartment of the abdomen showing the horizontal disposition of the  peritoneum    Fig. 18.19: Horizontal section through infracolic compartment of the abdomen showing the horizontal disposition of the peritoneum   3 The sacrogenital folds forming the lateral limit of the  rectovesical pouch;   5 The paravesical fossae. The sigmoid colon and  mesocolon are present, but are not shown in the  diagram.   1 The uterus and the broad ligaments form a transverse  partition across the pelvis.   Fig. 18,20: Horizontal section through the male pelvis showing  the horizontal disposition of the peritoneum   4 The mesovarium by which the ovary is suspended  from the posterior (superior) layer of the broad  ligament.    Synonyms: Foramen of Winslow, aditus or opening  to the lesser sac. This is a vertical slit-like opening  through which the lesser sac communicates with the  greater sac.   The foramen is situated behind the right free margin  of the lesser omentum at the level of the 12th thoracic  vertebra.   Anteriorly : Right free margin of the lesser omentum  containing the portal vein, proper hepatic artery, and  the bile duct (Fig. 18.22).   Posteriorly: The inferior vena cava, the right suprarenal  gland and T12 vertebra.   Inferiorly: First part of the duodenum and the horizontal  part of the hepatic artery (Fig. 18.23).    This is a large recess of the peritoneal cavity behind  the stomach, the lesser omentum and the caudate  lobe of the liver. It is closed all around, except in the  upper part of its right border where it communicates  with the greater sac through the epiploic foramen  (Figs 18.19 and 18.24).    Fig. 18.21: Horizontal section through the female pelvis showing the horizontal disposition of the peritoneum    Fig. 18.22: Epiploic foramen as seen in a transverse section at  the level of the twelfth thoracic vertebra   4 Peritoneum covering the anterior surface of body of  pancreas, left suprarenal, left kidney, splenic vessels  and diaphragm.   Reflection of peritoneum from neck of  pancreas to 1st part of duodenum.   1 The downward and forward course of the common  hepatic artery raises a sickle-shaped fold of  peritoneum from the posterior wall; this is known  as the right gastropancreatic fold. Similarly, the  upwards course of the left gastric artery raises  another similar fold, called the left gastropancreatic  fold. These folds divide the lesser sac into a superior  and an inferior recess (Figs 18.24 and 18.25).   2 The superior recess of the lesser sac lies behind the  lesser omentum and the liver. The portion behind  the lesser omentum is also known as the vestibule of  the lesser sac.   3 The inferior recess of the lesser sac lies behind the  stomach and within the greater omentum.   4 The splenic recess of the lesser sac lies between the  gastrosplenic and lienorenal ligaments.    • Strangulated internal hernia into the lesser sac  through epiploic foramen is approached through  the greater omentum because the epiploic foramen  cannot be enlarged due to the presence of  important structures all around it (Fig. 18.26).   • A posterior gastric ulcer may perforate into the  lesser sac. The leaking fluid passes out through  epiploic foramen to reach the hepatorenal pouch.  Sometimes in these cases the epiploic foramen is  closed by adhesions. Then the lesser sac becomes  distended, and can be drained by a tube passed  through the lesser omentum.   • Peritonitis: Parietal peritoneum of abdomen is  supplied by T7-T12 and LI nerves, while that of   Falciform ligament  Inferior vena cava  Superior recess of lesser sac  Vestibule  Coronary ligaments   Epiploic foramen  Lesser omentum  First part of duodenum  Right gastropancreatic fold  Transverse colon   a. By an opening in the closed gastrointestinal  tract in abdominal cavity, by ruptured appendix  or gastric ulcer perforation or typhoid ulcer  perforation.   c. Infection through vagina through uterine  cavity, fallopian tube to reach the peritoneal  cavity.    From a surgical point of view the peritoneal cavity has  two main parts, the abdomen proper and the pelvic  cavity. The abdominal cavity is divided by the  transverse colon and the transverse mesocolon into the  supracolic and infracolic compartments. The supracolic  compartment is subdivided by the reflection of  peritoneum around the liver into a number oisubphrenic  spaces. The infracolic compartment is also subdivided,  by the mesentery, into right and left parts. Further, the  right paracolic gutter lies along the lateral side of the  ascending colon, and the left paracolic gutter along the  lateral side of the descending colon (Fig. 18.27).   1 Right pneumo-enteric recess in the right wall of  dorsal mesogastrium grows to form the greater part  of the lesser sac, except for the vestibule.    Fig. 1 8.27: Subphrenic spaces shown in relation to the transverse  colon   a. The left anterior space or the left subphrenic space  lies between the left lobe of the liver and the  diaphragm, in front of the left triangular ligament.  Interiorly, it extends to the front of the lesser  omentum and of the stomach. Towards the left it  reaches the spleen. An abscess may form in this  space following operations on the stomach, the  spleen, the splenic flexure of the colon, and the  tail of the pancreas.   b. The left posterior space or the left subhepatic space  is merely the lesser sac which has already been  described.   c. The right anterior space or right subphrenic space  lies between the right lobe of the liver and the  diaphragm, in front of the superior layer of the  coronary ligament and the right triangular  ligament. Infection may spread to this space from  the gallbladder, or the vermiform appendix; or  may follow operations on the upper abdomen.   d. The right posterior space or right subhepatic space  is also called the hepatorenal pouch of Morrison.  It is described below.   e. The left extraperitoneal space lies around the left  suprarenal gland and the upper pole of the left  kidney. This is the site for a left perinephric  abscess.   f. Right extraperitoneal space lies around upper pole  of right kidney.   g. The midline extraperitoneal space corresponds to the  bare area of the liver. It lies between the bare area  and the diaphragm. It is bounded above and below  by the superior and inferior layers of the coronary  ligament. Infection can spread to this space from  the liver, resulting in liver abscess (Fig. 18.15).   1 The inferior surface of the right lobe of the liver.   Inferiorly : It opens into the general peritoneal cavity  (Fig. 18.28).   It lies between the ascending colon and the mesentery,  below the transverse mesocolon. It is triangular in shape  with its apex directed downwards (Fig. 18.28).    It lies between the descending colon and the mesentery.  It is also triangular with its apex directed upwards.  Inferiorly, it opens freely into the pelvis.   The right lateral paracolic gutter opens freely into the  hepatorenal pouch at its upper end. It may be infected  by a downwards spread of infection from the  hepatorenal pouch or from the lesser sac, or by an  upward spread from the appendix.   The left lateral paracolic gutter opens freely into the  pelvis at its lower end. Above it is separated from the  spleen and from the lienorenal space by the  phrenicocolic ligament. It may be infected from the  supracolic compartment, or by an upward spread of  infection from the pelvis (Fig. 18.28).   This is the most dependent part of the peritoneal cavity  when the body is in the upright position. In the supine  position, it is the most dependent part of the pelvic  cavity (Fig. 18.30).   • Anteriorly , by the uterus and the posterior fornix of  the vagina.   Fig. 18.30: Left view of a sagittal section through the rectouterine  pouch    * Intraperitoneal subphrenic spaces may get  distended by collection of pus. These are called  subphrenic abscesses (Fig. 18.31).   * Hepatorenal space is of considerable importance  as it is the most dependent (lowest) part of the  abdominal cavity proper when the body is supine.  Fluids tend to collect here. This is the commonest  site of a subphrenic abscess, which may be caused  by spread of infection from the gallbladder, the  appendix, or other organs in the region (Figs 18.27  and 18.28).   * The floor of the rectouterine pouch is 5.5 cm from  the anus, and can be easily felt with a finger passed  through the rectum or the vagina. The corres¬  ponding rectovesical pouch in males lies 7.5 cm  above the anus (Fig. 18.28).   Being the most dependent part of the peritoneal  cavity, pus tends to collect here.   The infected fluid collects mostly in subphrenic  space especially the hepatorenal pouch as it is  deepest when person is lying supine. If patient  sits in inclined position, the infected material  tracks down to rectouterine pouch in female or to  rectovesical pouch in male (Figs 18.29 and 18.30).    These are small pockets of the peritoneal cavity  enclosed by small, inconstant folds of peritoneum. They  commonly occur at the transitional zones between the  absorbed and unabsorbed parts of the mesentery. These  are best observed in foetuses, and are mostly obliterated  in adults. Sometimes they persist to form potential sites  for internal hernia and their strangulation.   The lesser sac is the largest recess. It is always present,   1 The superior duodenal recess is present in about 50%  of subjects. It is situated at the level of vertebra L2. It  is about 2 cm deep. Its orifice looks downwards  (Fig. 18.32).   2 The inferior duodenal recess is present in about 75% of  subjects. It is situated at the level of vertebra L3. It is  about 3 cm deep. Its orifice looks upwards.   3 The paraduodenal recess is present in about 20% of  subjects. The inferior mesenteric vein lies in the free  edge of the peritoneal fold. Its orifice looks to the  right.   4 The retroduodenal recess is present occasionally. It is  the largest of the duodenal recesses. It is 8 to 10 cm  deep. Its orifice looks to the left.   5 The duodenojejunal or mesocolic recess is present in  about 20% of subjects. It is about 3 cm deep. Its orifice  looks downwards and to the right.   6 The mesentericoparietal fossa of Waldeyer is present  in about 1% of subjects. It lies behind the upper part  of the mesentery. Its orifice looks to the left. The  superior mesenteric vessels lie in the fold of  peritoneum covering this fossa.   1 The superior ileocaecal recess is quite commonly  present. It is formed by a vascular fold present  between the ileum and the ascending colon. Its orifice  looks downwards and to the left (Fig. 18.33).   2 The inferior ileocaecal recess is covered by the bloodless  fold of Treves. The orifice of the recess looks  downwards and to the left.   3 The retrocaecal recess lies behind the caecum. It often  contains the appendix. Its orifice looks downwards.   This recess is constantly present in the foetus and in  early infancy, but may disappear with age. It lies behind  the apex of the sigmoid mesocolon. Its orifice looks  downwards (Fig. 18.34).    • Internal hernia: May occur in the opening of lesser  sac. It may also occur in between paraduodenal  recesses. One has to remember the inferior  mesenteric vein in the paraduodenal fold during  reduction of the hernia (Fig. 18.32).   • Pain of foregut derived structures is felt in the  epigastric area.   • Pain of midgut derived structures is felt in the  periumbilical area (Fig. 18.35).   • Pain of hindgut derived structures is felt in the  suprapubic area.   • Palpation of the abdominal viscera is done when  the patient is in supine position, and the hip and  knee are flexed. In extended position fascia lata  of thigh exerts a pull on the inguinal ligament,  making palpation difficult.   The primitive gut is formed by incorporation of  secondary yolk sac into the embryo. The gut is divided  into the following.   1 Pharyngeal gut (from buccopharyngeal membrane  to tracheobronchial diverticulum). Its derivatives  have been dealt in Volume 3.    2 Foregut situated caudal to pharyngeal gut till the  origin of hepatic bud.   3 Midgut extends from origin to hepatic bud  downwards. Its terminal point is the junction of right  two-thirds and left one-third of transverse colon of  adult. It communicates with the yolk sac.   4 Hindgut spans between the end of midgut and the  cloacal membrane.   Dorsal mesentery is double fold of peritoneum  connecting the caudal part of foregut, midgut and most  of the hindgut to the posterior abdominal wall. It is  subdivided into mesogastrium and mesoduodenum for  foregut, into dorsal mesentery proper for jejunum and  ileum; and mesentery of vermiform appendix,  transverse and pelvic mesocolons for large intestine.  Ventral mesentery only exists ventral to the foregut. It  is a derivative of the septum transversum.    * There are 9 regions of the abdominal cavity. These  are right and left hypochondrium and middle  epigastrium in upper part. In middle part are right  and left lumbar and middle umbilical regions. In  the lower part are right and left iliac fossae and  middle hypogastrium.   • Abdominal part of foregut has a dorsal and ventral  mesentery each.   * Lesser sac with its fluid prevents compression of  most of the posterior abdominal organs by the full  stomach.   ■ Rectouterine pouch in female is 5.5 cm from surface  of perineal skin.   * Rectovesical pouch in male is 7.5 cm away from  the perineal skin.   • Peritoneal recesses are mostly present at the junction  of intraperitoneal and retroperitoneal organs.   • Right posterior subphrenic space or Morrison's  pouch is the deepest pouch in lying position.   # Spleen forming stomach bed is separated from  stomach by the cavity of greater sac. Other organs  forming bed are separated from stomach by lesser  sac.    An alcoholic patient has swelling of abdomen with  veins radiating from the umbilicus   Ans: In alcoholism, the liver is the site of insult. The  hepatic cells shrink and get replaced by fibrous  tissue. The portal vein is not able to empty its blood  due to fibrosis. Pressure in portal vein, splenic vein  and superior mesenteric vein rises leading to  exudation of fluid and oedema. The veins around  the umbilicus is an anastomoses between the  paraumbilical veins tributaries of portal vein and  superior and inferior epigastric veins, tributaries of  vena cavae. This is a site of portosystemic  anastomoses and is an attempt to take the portal  blood back into systemic circulation.   10. Ganglia situated in the submucosal and myenteric  plexuses of intestine is  a. Sympathetic b. Parasympathetic   Only about one centimeter of oesophagus lies in the  abdominal cavity. It acquires great importance as it is  a site of portosystemic anastomoses.   Stomach is the chief organ in the epigastric and left  hypochondriac regions. Its lesser curvature bears the  brunt of all fluids which are too hot or too cold,  including the insults by the alcoholic beverages.   Identify the stomach and trace it towards the abdominal  part of oesophagus. Clean this part of oesophagus.  Note various parts of stomach, e.g. cardiac end, fundus,  body and pyloric parts. Trace the right and left gastric  arteries along the lesser curvature and right and left  gastroepiploic arteries along the greater curvature.   Tie two ligatures each at the lowest part of  oesophagus and the pylorus. Remove the stomach by  cutting between two upper ligatures through the  oesophagus, left gastric artery, gastrophrenic ligament;  and by cutting the pylorus between the lower two  ligatures. Free the stomach from the adherent  peritoneum if any and put it in a tray for further dissection.    1 The abdominal part of the oesophagus is only about  1.25 cm long (Fig. 19.1).   2 It enters the abdomen through the oesophageal  opening of the diaphragm situated at the level of  vertebra T10, slightly to the left of the median plane.  It continues with the cardiac end of stomach (Fig. 19.2).   3 The oesophageal opening also transmits the anterior  and posterior gastric nerves, the oesophageal branches  of the left gastric artery and the accompanying veins.    4 These veins of oesophagus drain partly into portal  and partly into systemic circulation. Veins accom¬  panying left gastric vein drain into portal vein.  Others drain into hemiazygos, in thoracic cavity,  and continue into vena azygos and superior vena  cava. So it is a site of portosystemic anastomoses  (Fig. 19.3).   5 The oesophagus runs downwards and to the left in  front of the left crus of the diaphragm and of the  inferior surface of the left lobe of the liver, and ends  by opening into the cardiac end of the stomach at the  level of vertebra Til, about 2.5 cm to the left of the  median plane. Its right border is continuous with the  lesser curvature of the stomach, but the left border  is separated from the fundus of the stomach by the  cardiac notch (Figs 19.2 and 19.3). Peritoneum covers  the oesophagus only anteriorly and on the left side.    6 Anterior gastric nerve contains mainly the left vagal  fibres, and the posterior gastric nerve mainly the  right vagal fibres. Each gastric nerve is represented  by one or two trunks and combines a few sym¬  pathetic fibres from the greater splanchnic nerve  (Fig. 19.12a).   Mucous membrane —Epithelial lining is stratified  squamous nonkeratinised in nature. Lamina propria  consists of loose connective tissue with papillae.   Muscularis mucosae is distinct in lower part and  formed by longitudinal muscle fibres.   Muscularis externa is composed of striated muscle in  upper third, mixed type in middle third and smooth  muscles in lower third. Its outer layer comprises of  longitudinal coat and inner layer comprises of circular  coat of muscle fibres.    • The lower end of the oesophagus is one of the  important sites for portosystemic anastomoses. In  portal hypertension, the anastomoses opens and  forms venous dilatations called oesophageal varices.  Their rupture causes severe and dangerous  haematemesis (Fig. 19.4).   • Normally the lower end of the oesophagus  remains closed and dilates only during the passage  of food. However, due to neuromuscular  incoordination it may fail to dilate leading to  difficulty in passage of food or dysphagia. The  condition is known as achalasia cardia. Marked  dilatation of the oesophagus may occur due to  collection of food in it (Fig. 19.5).   • The lower end of the oesophagus is also prone to  inflammation or ulceration by regurgitation of  acid from the stomach. It is the commonest site of  oesophageal carcinoma. Next site is the middle  third of oesophagus.   • Hiatal hernia occurring through the oesophageal  opening and can be rolling or paraoesophageal  and sliding (Figs 19.6a and b).   • Barrett's oesophagus: Squamous epithelium of  lower oesophagus may be replaced by columnar  epithelium in certain clinical conditions. The  abnormal type of epithelium present in oesophagus  is referred as Barrett's epithelium.   • Tracheo-oesophageal fistula: At times the separation  of trachea and oesophagus may not be complete.  Proximal segment ends in a blind pouch and distal  segment communicates with trachea (Fig. 19.7).   • The lumen of the oesophagus may be abnormally  narrowed due to improper canalisation.   • The lumen of oesophagus may not be canalised at  all leading to oesophageal stenosis.    The stomach is also called the gaster or venter from  which we have the adjective gastric applied to  structures related to the organ (Fig. 19.1).   Figs 19.6a and b: Hiatal hernia: (a) Rolling, and (b) sliding   The stomach is a muscular bag forming the widest and  most distensible part of the digestive tube. It is  connected above to the lower end of the oesophagus,  and below to the duodenum. It acts as a reservoir of  food and helps in digestion of carbohydrates, proteins  and fats.   The stomach lies obliquely in the upper and left part of  the abdomen, occupying the epigastric, umbilical and  left hypochondriac regions. Most of it lies under cover  of the left costal margin and the ribs (Figs 19.1 and 19.8).   The shape of the stomach depends upon the degree of  its distension and that of the surrounding viscera, e.g.  the colon. When empty, the stomach is somewhat  J-shaped (vertical) (Fig. 19.2); when partially distended,  it becomes pyriform in shape. In obese persons, it is  more horizontal. The shape of the stomach can be  studied in the living by radiographic examination after  giving a barium meal ( see Fig. 36.2).   The stomach is a very distensible organ. It is about  25 cm long, and the mean capacity is one ounce (30 ml)  at birth, one litre (1000 ml) at puberty, and IVi to 2 liters  or more in adults.   The stomach has two orifices or openings, two  curvatures or borders, and two surfaces (Fig. 19.2).   The cardiac orifice is joined by the lower end of the  oesophagus. It lies behind the left 7th costal cartilage  2.5 cm from its junction with the sternum, at the level  of vertebra Til. There is physiological evidence of  sphincteric action at this site, but a sphincter cannot be  demonstrated anatomically.   The pyloric orifice opens into the duodenum. In an  empty stomach and in the supine position, it lies 1.2 cm  to the right of median plane, at the level of lower border  of vertebra LI or transpyloric plane. Its position is  indicated on the surface of the stomach:   a. By a circular groove (pyloric constriction , i.e. sthenic.  Sometime it may be hyposthenic (thin and long)  hypersthenic pylorus) produced by the underlying  pyloric sphincter or pylorus (pylorus = gate guard)  which feels like a large firm nodule (Fig. 19.2).   b. By the prepyloric vein which lies in front of the  constriction (Fig. 19.3).   The lesser curvature is concave and forms the right  border of the stomach. It provides attachment to the  lesser omentum. The most dependent part of the  curvature is marked by the angular notch or incisura  angularis (Fig. 19.2).   The greater curvature is convex and forms the left  border of the stomach ( see Figs 18.9 and 18.18). It  provides attachment to the greater omentum, the  gastrosplenic ligament and the gastrophrenic ligament.  At its upper end the greater curvature presents the  cardiac notch which separates it from the oesophagus.   The stomach is lined by peritoneum on both its surfaces.  At the lesser curvature the layers of peritoneum lining  the anterior and posterior surfaces meet and become  continuous with the lesser omentum (see Fig. 18.8).   Along the greater part of the greater curvature the  two layers meet to form the greater omentum.   Near the fundus the two layers meet to form the  gastrosplenic ligament.   Near the cardiac end the peritoneum on the posterior  surface is reflected on to the diaphragm as the  gastrophrenic ligament (see Fig. 18.8). Cranial to this  ligament a small part of the posterior surface of the  stomach is in direct contact with the diaphragm (left  crus). This is the bare area of the stomach. The greater  and lesser curvatures along the peritoneal reflections  are also bare.   The stomach is divided into two parts, (i) Cardiac and  (ii) Pyloric, by a line drawn downwards and to the left  from the incisura angularis. The larger, cardiac part is  further subdivided into the fundus and body, and the  smaller, pyloric part is subdivided into the pyloric  antrum and pyloric canal (Fig. 19.2).   1 The fundus of the stomach is the upper convex dome¬  shaped part situated above a horizontal line drawn  at the level of the cardiac orifice. It is commonly  distended with gas which is seen clearly in  radiographic examination under the left dome of the  diaphragm ( see Fig. 20.14).   The anterior surface of the stomach is related to the  liver, the diaphragm, transverse colon and the anterior  abdominal wall. The areas of the stomach related to  these structures are shown in Fig. 19.8. The diaphragm  separates the stomach from the left pleura, the  pericardium, and the sixth to ninth ribs. The costal  cartilages are separated from the stomach by the  transversus abdominis. Gastric nerves and vessels  ramify deep to the peritoneum.   The space between left costal margin and lower edge  of left lung on stomach is known as Traube's space.  Normally, on percussion there is resonant note over  this space; but in splenomegaly or pleural effusion, a  dull note is felt at this site.    2 The body of the stomach lies between the fundus and  the pyloric antrum. It can be distended enormously  along the greater curvature. The gastric glands  distributed in the fundus and body of stomach,  contain all three types of secretory cells, namely:   b. The chief, peptic or zymogenic cells which secrete  the digestive enzymes.   1 The pyloric antrum is separated from the pyloric canal  by an inconstant sulcus, sulcus intermedius present  on the greater curvature. It is about 7.5 cm long. The  pyloric glands are richest in mucous cells.   2 The pyloric canal is about 2.5 cm long. It is narrow  and tubular. At its right end it terminates at the  pylorus.    Fig. 19.8: Anterior relations of stomach. Area 1st is covered by  the liver; area 2nd by the diaphragm; and area 3rd by the anterior  abdominal wall    The posterior surface of the stomach is related to  structures forming the stomach bed, all of which are  separated from the stomach by the cavity of the lesser sac .   g. Splenic artery (Fig. 19.9). Sometimes the spleen is  also included in the stomach bed, but it is  separated from the stomach by the cavity of the  greater sac (and not of the lesser sac). Gastric  nerves and vessels ramify deep to the peritoneum  (Figs 19.10 and 19.12).   1 The left gastric artery, a branch of the coeliac trunk.   3 Along the greater curvature it is supplied by the right  gastroepiploic artery, a branch of the gastroduodenal.   5 Fundus is supplied by 5 to 7 short gastric arteries,  which are also branches of the splenic artery  (Fig. 19.10).   The veins of the stomach drain into the portal,  superior mesenteric and splenic veins.   Right and left gastric drain in the portal vein. Right  gastroepiploic ends in superior mesenteric vein; while  left gastroepiploic and short gastric veins terminate in  splenic vein (Fig. 19.3).   The stomach can be divided into four lymphatic  territories as shown in Fig. 19.11. The drainage of these  areas is as follows.   Area (a) of Fig. 19.11, i.e. upper part of left l/3rd  drains into the pancreaticosplenic nodes lying along the  splenic artery, i.e. on the back of the stomach. Lymph  vessels from these nodes travel along the splenic artery  to reach the coeliac nodes.   Area (b), i.e. right 2/3rd drains into the left gastric  nodes lying along the artery of the same name. These  nodes also drain the abdominal part of the oesophagus.  Lymph from these nodes drains into the coeliac nodes.   Area (c), i.e. lower part of left l/3rd drains into the  right gastroepiploic nodes that lie along the artery of  the same name. Lymph vessels arising in these nodes  drain into the subpyloric nodes which lie in the angle  between the first and second parts of the duodenum.  From here the lymph is drained further into the hepatic  nodes that lie along the hepatic artery; and finally into  the coeliac nodes.   Lymph from area (d), i.e. pyloric part drains in  different directions into the pyloric, hepatic, and left   Fig. 19.11: Lymphatic drainage of the stomach. Note the manner  in which the organ is subdivided into a to d different territories   gastric nodes, and passes from all these nodes to the  coeliac nodes.   Note that lymph from all areas of the stomach  ultimately reaches the coeliac nodes. From here it passes  through the intestinal lymph trunk to reach the cisterna  chyli .   The stomach is supplied by sympathetic and  parasympathetic nerves. The sympathetic nerves are  derived from thoracic six to ten segments of the spinal  cord, via the greater splanchnic nerves, and coeliac and  hepatic plexuses. They travel along the arteries  supplying the stomach. These nerves are:   b. Motor to the pyloric sphincter, but inhibitory to  the rest of the gastric musculature.   The parasympathetic nerves (Figs 19.12a and b) are  derived from the vagi, through the oesophageal plexus  and gastric nerves. The anterior gastric nerve (made  up of one or two trunks) contains mainly the left vagal  fibres, and the posterior gastric nerve (again made up  of one to two trunks) contains mainly the right vagal  fibres.   a. A number of gastric branches for the anterior  surface of the fundus and body of the stomach.   b. Two pyloric branches, one for the pyloric antrum  and another for the pylorus.   a. Smaller, gastric branches for the posterior surface  of the fundus, the body and the pyloric antrum.   b. Larger, coeliac branches for the coeliac plexus.  Parasympathetic nerves are motor and secreto-  motor to the stomach. Their stimulation causes  increased motility of the stomach and secretion  of gastric juice rich in pepsin and HC1. These are  inhibitory to the pyloric sphincter.   Open the stomach along the greater curvature and  examine the mucous membrane with a hand lens.   Then strip the mucous membrane from one part and  expose the internal muscle coat. Dissect the muscle  coat, e.g. outer longitudinal, middle circular and inner  oblique muscle fibres. Feel thickened pyloric sphincter.   Incise the beginning of duodenum and examine the  duodenal and pyloric aspects of the pyloric sphincter.   Figs 19.12a and b: Nerve supply of the stomach: (a) Anterior  gastric nerve, and (b) posterior gastric nerve   The stomach has to be opened to see its internal structure.   1 The mucosa of an empty stomach is thrown into folds  termed as gastric rugae. The rugae are longitudinal  along the lesser curvature and are irregular  elsewhere. The rugae are flattened in a distended  stomach. On the mucosal surface there are numerous  small depressions that can be seen with a hand lens.  These are the gastric pits. The gastric glands open into  these pits.   The part of the lumen of the stomach that lies along  the lesser curvature, and has longitudinal rugae, is  called the gastric canal or magenstrasse . This canal  allows rapid passage of swallowed liquids along the  lesser curvature directly to the lower part before it  spreads to the other part of stomach (Fig. 19.13).   Thus lesser curvature bears maximum insult of  the swallowed liquids, which makes it vulnerable to  peptic ulcer. So, beware of your drinks.   2 Submucous coat is made of connective tissue,  arterioles and nerve plexus.   b. Inner circular fibres encircle the body and are  thickened at pylorus to form pyloric sphincter  (Fig. 19.14).    c. The deepest layer consists of oblique fibres which  loop over the cardiac notch. Some fibres spread  in the fundus and body of stomach. Rest form a  well-developed ridge on each side of the lesser  curvature. These fibres on contraction form  "gastric canal" for the passage of fluids.   1 The stomach acts primarily as a reservoir of food. It  also acts as a mixer of food.   2 By its peristaltic movements it softens and mixes the  food with the gastric juice.    3 The gastric glands produce the gastric juice which  contains enzymes that play an important role in  digestion of food.   4 The gastric glands also produce hydrochloric acid  which destroys many organisms present in food and  drink.   5 The lining cells of the stomach produce abundant  mucus which protects the gastric mucosa against the  corrosive action of hydrochloric acid.   6 Some substances like alcohol, water, salt and few  drugs are absorbed in the stomach.   7 Stomach produces the "intrinsic factor" of Castle  which helps in the absorption of vitamin B 12 .    * Gastric pain is felt in the epigastrium because the  stomach is supplied from segments T6 to T9 of  the spinal cord, which also supply the upper part  of the abdominal wall. Pain is produced either by  spasm of muscle, or by over-distension. Ulcer pain  is attributed to local spasm due to irritation (see  Fig. 18.35).   • Peptic ulcer can occur in the sites of pepsin and  hydrochloric acid, namely the stomach, first part  of duodenum, lower end of oesophagus and  MeckeTs diverticulum. It is common in blood  group 'O'.   Gastric ulcer occurs typically along the lesser  curvature (Fig. 19.13). This is possibly due to the  following peculiarities of lesser curvature.   d. Blood supply is less abundant and there are  fewer anastomoses.   f. Because of the gastric canal, it receives most of  the insult from irritating drinks.   g. Being shorter in length the wave of contraction  stays longer at a particular point, viz., the  standing wave of incisura.   Gastric ulcers are common in people who are  always in "hurry", mostly "worry" about incidents  and eat "spicy curry".   Gastric ulcer is notoriously resistant to healing  and persists for years together, causing great  degree of morbidity. To promote healing the  irritating effect of HC1 can be minimised by  antacids, partial gastrectomy or vagotomy.   * Gastric carcinoma is common and occurs along the  greater curvature. On this account the lymphatic  drainage of stomach assumes importance.  Metastasis can occur through the thoracic duct to  the left supraclavicular lymph node (Troisier's  sign). These lymph nodes are called as "signal  nodes". It is common in blood group 'A'.   It causes visible peristalsis in the epigastrium, and  vomiting after meals.   * Hyposthenic stomach is more prone for gastric ulcer,  while hypersthenic stomach is prone for duodenal  ulcer.   At the cardiac end of stomach the stratified epithelium  of oesophagus abruptly changes to simple columnar  epithelium of stomach.   • Parietal cells are large and pink, Chief cell are small and blue    Mucous membrane: The epithelium is simple columnar  with small tubular glands. Lower half of the gland is  secretory and upper half is the conducting part.  Muscularis mucosae consists of smooth muscle fibres.   Submucosa: It consists of loose connective tissue with  Meissner's (German histologist 1829-1909) plexus.   Muscularis externa: It is made of outer longitudinal and  inner circular layer including the myenteric plexus  of nerves or Auerbach's plexus (German anatomist  1828-97).   The posterior part of foregut forms the oesophagus. It  is very small in the beginning, but it lengthens due to  descent of lungs and heart. The muscle of upper one-  third is striated, middle one-third, mixed, and lower  one-third smooth. Nerve supply to upper two-thirds is  from vagus and to lower one-third is from autonomic  plexus. Epithelium of oesophagus is endodermal and  rest of the layers are from splanchnic mesoderm.   Mucous membrane: It contains tall simple tubular gastric  glands. Upper one-third is conducting, while lower  two-thirds is secretory. The various cell types seen in  the gland are chief or zymogenic, oxyntic or parietal  and mucous neck cells (Fig. 19.15).   Muscularis externa: It contains an additional innermost  oblique coat of muscle fibres.   Mucous membrane: There are pyloric glands which  consist of basal one-third as mucus secretory  component and upper two-thirds as conducting part.  Muscularis mucosae is made of two layers of fibres.  Submucosa is same as in the cardiac end.   Muscularis externa comprises thick layer of circular  fibres forming the pyloric sphincter. Serosa is same as  of cardiac end.    The caudal part of foregut shows a fusiform dilatation  with anterior and posterior borders and left and right  surfaces. This is the stomach. It rotates 90° clockwise,  so that left surface faces anteriorly. Even the original  posterior border of stomach grows faster, forming the  greater curvature.   The stomach also rotates along anteroposterior axis,  so that distal or pyloric part moves to right and  proximal or cardiac part moves to left side.   The 90° rotation of stomach along the vertical axis  pulls the dorsal mesogastrium to the left side creating  the lessor sac or omental bursa.   Spleen appears as mesodermal condensation in the  left leaf of dorsal mesogastrium.    • Abdominal part of oesophagus is the site of porto¬  systemic anastomoses. Some veins drain into  hemiazygos -»vena azygos superior vena cava.  Other veins drain into oesophageal veins -»left  gastric vein —» portal vein.   • Anterior gastric nerve contains left vagal fibres and  posterior gastric nerve contains right vagal fibres.   • Lesser curvature is the anterior border and greater  curvature is the posterior border.   • Stomach bed is separated from the stomach by  lesser sac.    * The gastric ulcer is common in people who"worry,  hurry and eat hot curries". Gastric ulcer commonly  occurs along lesser curvature.   • Gastric cancer mostly occurs along greater  curvature. Lymph from cancer —> thoracic duct^  left, supraclavicular node. It is called Virchow's  node. This sign is called Troisier's sign.    A young executive complained of pain in the  abdomen, above the umbilicus. He was always in  "hurry", gets 'worried' very often and loves to eat  spicy "curries".   Ans: The young man is suffering from gastric ulcer.  The sympathetic nerves to the stomach are supplied  by segments T6-T9 of the spinal cord, which also  supply the upper part of the abdominal walls so the  pain of gastric ulcer is referred to epigastric region.  The pain of foregut derived areas is referred to  epigastric region; those of midgut derived organs to  periumbilical region while those of hind gut derived  viscera to the suprapubic region.   2. Which of the following is not present in the bed of  stomach?   3. A posteriorly perforating peptic ulcer will most  likely produce peritonitis in the following:    Which of the following arteries supply the fundus  of the stomach?   5. Which cell of gastric gland gives it a beaded  appearance?   6. Cardiac orifice of stomach lies behind one of the  following costal cartilages:   The intestine, which is the longest part of the digestive  tube, is divided into long, less distensible, small  intestine, and shorter, more distensible large intestine.  Food has to be digested, metabolised and stored for  expulsion in the intestines. Intestines suffer from  bacterial infection like typhoid, tuberculosis; parasitic  infection, like roundworm, tape worm, etc. in addition  to diarrhoea and dysentery. Good and healthy eating  habits definitely prevent some of these conditions.   The proximal one and a half parts of duodenum,  including liver, gallbladder and pancreas, develop from  foregut. The distal two and a half parts of duodenum,  jejunum, ileum, caecum, appendix, ascending colon and  right two-thirds of transverse colon develop from  midgut. Lastly, the left one-third of transverse colon,  descending colon, pelvic colon and proximal part of  rectum develop from hind gut.    The small intestine extends from the pylorus to the  ileocaecal junction. It is about 6 meters long. The length  is greater in males than in females, and greater in  cadavers, due to loss of tone than in the living. It is  divided into:   1 An upper, fixed part, called the duodenum, which  measures about 25 cm in length; and   2 A lower, mobile part, forming a very long convoluted  tube.   The upper two-fifths of the mobile intestine are  known as the jejunum, and the lower three-fifths are  known as the ileum (Fig. 20.1). The structure of the small  intestine is adapted for digestion and absorption.   For absorption of digested food a very large surface  area is required. This is achieved by:   b. The presence of circular folds of mucous  membrane, villi and microvilli.   The circular folds of mucous membrane , plicae circulares,  or valves ofKerkring form complete or incomplete circles.  These folds are permanent, and are not obliterated by  distension. They begin in the second part of the  duodenum, and become large and closely set below the  level of the major duodenal papilla. They continue to  be closely set in the proximal half of the jejunum  (Fig. 20.2), but diminish progressively in size and  number in the distal half of the jejunum and in the  proximal half of the ileum (Fig. 20.3). They are almost    absent in the distal half of the ileum. Apart from  increasing the surface area for absorption, the circular  folds facilitate absorption by slowing down the passage  of intestinal contents.   The intestinal villi are finger-like projections of  mucous membrane, just visible to the naked eye. They  give the surface of the intestinal mucosa a velvety  appearance. They are large and numerous in the  duodenum and jejunum, but are smaller and fewer in  the ileum. They vary in density from 10 to 40 per square  millimeter, and are about 1 to 2 mm long. They increase  the surface area of the small intestine about eight times  (Fig. 20.4).   Each villus is covered by a layer of absorptive  columnar cells. The surface of these cells has a striated  border which is seen, under the electron microscope to  be made of microvilli.   These are simple tubular glands distributed over the  entire mucous membrane of the jejunum and ileum.  They open by small circular apertures on the surface of  mucous membrane between the villi. They secrete  digestive enzymes and mucus. The epithelial cells deep  in the crypts show a high level of mitotic activity. The  proliferated cells gradually move towards the surface,  to be shed from the tips of the villi. In this way, the  complete epithelial lining of the intestine is replaced  every two to four days.   The mucous membrane of the small intestine contains  two types of lymphatic follicles. The solitary lymphatic  follicles are 1 to 2 mm in diameter, and are distributed  throughout the small and large intestines. The  aggregated lymphatic follicles or Peyer's patches form  circular or oval patches, varying in length from 2 to  10 cm and containing 10 to over 200 follicles. They are  largest and most numerous in the ileum, and are small,  circular and fewer in the distal jejunum. They are placed  lengthwise along the antimesenteric border of the  intestine. Peyer's patches get ulcerated in typhoid fever,  forming oval ulcers with their long axes along the long  axis of the bowel.   Both the solitary and aggregated lymphatic follicles  are most numerous at puberty, but thereafter diminish  in size and number, although they may persist up to  old age.   Each villus has a central lymph vessel called a lacteal.  Lymph from lacteals drains into plexuses in the walls  of the gut and from there to regional lymph nodes.   The arterial supply to jejunum and ileum is derived from  the jejunal and ileal branches of the superior mesenteric  artery. The vasa recta are distributed alternately to the  opposite surfaces of the gut. They run between the  serous and muscular coats, and give off numerous  branches which supply and pierce the muscular coat    and form a plexus in the submucosa. From this plexus,  minute branches pass to the glands and villi.   The lymphatics (lacteals) have a circular course in the  walls of the intestine. Tuberculous ulcers and  subsequent strictures are due to involvement of these  lymphatics. Large lymphatic vessels formed at the  mesenteric border pass to the mesenteric lymph nodes.   The nerve supply of the small intestine is sympathetic  (T9 to Til) as well as parasympathetic (vagus), both of  which pass through the coeliac and superior mesenteric  plexuses. ,   The nerves form the myenteric plexus of Auerbach,  containing parasympathetic ganglia between circular  and longitudinal muscle coats. Fibres from this plexus  form the submucous plexus of Meissner which also  contains parasympathetic ganglia.   Sympathetic nerves are motor to the sphincters and  to the muscularis mucosae, and inhibitory for peristaltic  movements.   The nerve plexuses and neurotransmitters of the gut  are quite complex. These are called the enteric nervous  system.   The function of the small intestine comprises digestion  and absorption of the digested contents from the fluid.   The parts of the small intestine are considered one  by one.   The duodenum is the shortest, widest and most fixed  part of the small intestine. It extends from the pylorus  to duodenojejunal flexure. It is curved around the head  of pancreas in the form of letter 'C'. The duodenum  lies above the level of umbilicus, opposite first, second  and third lumbar vertebrae.   Duodenum is 25 cm long and is divided into the  following four parts (Figs 20.6 and 20.7).   1 First or superior part, 5 cm or 2 inches long.   2 Second or descending part, 7.5 cm or 3 inches long.   3 Third or horizontal part, 10 cm or 4 inches long.   4 Fourth or ascending part, 2.5 cm or 1 inch long.   Examine the C-shaped duodenum and head of  pancreas lying in its concavity (Fig. 20.5). Cut through  the lower wall of the first part extending the cut on medial  wall of second and upper wall of third part of duodenum  to see its interior.   Carefully look for the longitudinal fold on the  posteromedial wall below the middle of second part.  The longitudinal fold is often covered by a circular fold  containing orifice of the major duodenal papilla draining  both the bile and pancreatic ducts.   Identify and dissect the structures related to all the  four parts of the duodenum.   The term duodenum is a Latin corruption of the Greek  word, dudekadactulos, meaning twelve fingers long.    The duodenum is mostly retroperitoneal and fixed,  except at its two ends where it is suspended by folds of  peritoneum, and is, therefore, mobile. Anteriorly, the  duodenum is only partly covered with peritoneum.   The first part begins at the pylorus, and passes  backwards, upwards and to the right to meet the second  part at the superior duodenal flexure. Its relations are  as follows.   1 The proximal 2.5 cm is movable. It is attached to the  lesser omentum above, and to the greater omentum  below ( see Fig. 18.8).   2 The distal 2.5 cm is fixed. It is retroperitoneal. It is  covered with peritoneum only on its anterior aspect.   This part is about 7.5 cm long. It begins at the superior  duodenal flexure, passes downwards to reach the lower  border of the third lumbar vertebra, where it curves  towards the left at the inferior duodenal flexure, to  become continuous with the third part. Its relations are  as follows.   It is retroperitoneal and fixed. Its anterior surface is  covered with peritoneum, except near the middle,  where it is directly related to the colon.   1 Anterior surface of the right kidney near the medial  border    Figs 20.8a and b: Relations of the first part of the duodenum: (a) Sagittal section viewed from the left side, and (b) posterior  relations    Figs 20.9a and b: Relations of the second part of the duodenum: (a) Anterior relations, and (b) posterior relations    The interior of the second part of the duodenum  shows the following special features.   a. The major duodenal papilla is an elevation present  posteromedially, 8 to 10 cm distal to the pylorus.  The hepatopancreatic ampulla opens at the  summit of the papilla.   b. The minor duodenal papilla is present 6 to 8 cm distal  to the pylorus, and presents the opening of the  accessory pancreatic duct (see Fig. 23.16).   c. Below major duodenal papilla, a longitudinal fold  called plica longitudinalis is seen.   This part is about 10 cm long. It begins at the inferior  duodenal flexure, on the right side of the lower border  of the third lumbar vertebra. It passes almost  horizontally and slightly upwards in front of the  inferior vena cava, and ends by joining the fourth part  in front of the abdominal aorta. Its relations (Fig. 20.10)  are as follows.   It is retroperitoneal and fixed. Its anterior surface is  covered with peritoneum, except in the median plane,  where it is crossed by the superior mesenteric vessels  and by the root of the mesentery.   5 Abdominal aorta with origin of inferior mesenteric  artery (Fig. 20.10b).   This part is 2.5 cm long. It runs upwards on or  immediately to the left of the aorta, up to the upper  border of the second lumbar vertebra, where it turns  forwards to become continuous with the jejunum at the  duodenojejunal flexure. Its relations are as follows.   It is mostly retroperitoneal, and covered with  peritoneum only anteriorly. The terminal part is  suspended by the uppermost part of the mesentery, and  is mobile.    Figs 20.10a and b: Relations of the third part of the duodenum: (a) Anterior relations, and (b) posterior relations    Fig. 20.11 : Posterior relations of the fourth part of the duodenum   To the right: Attachment of the upper part of the root of  the mesentery (Fig. 20.10).   This is a fibromuscular band which suspends and  supports the duodenojejunal flexure. It arises from the  left crus of the diaphragm, close to the right side of the  oesophagus, passes downwards behind the pancreas,  and is attached to the posterior surface of the  duodenojejunal flexure and the third and fourth parts  of the duodenum (Fig. 20.12).    Normally its contraction increases the angle of the  duodenojejunal flexure. Sometimes it is attached only  to the flexure, and then its contraction may narrow the  angle of the flexure, causing partial obstruction of the  gut.   The duodenum develops partly from the foregut and  partly from the midgut. The opening of the bile duct  into the second part of the duodenum represents the  junction of the foregut and the midgut. Up to the level  of the opening, the duodenum is supplied by the  superior pancreaticoduodenal artery , and below it by the  inferior pancreaticoduodenal artery (Fig. 20.13).   b. The supraduodenal artery of Wilkie, which is  usually a branch of the common hepatic artery.   The veins of the duodenum drain into the splenic,  superior mesenteric and portal veins.   Most of the lymph vessels from the duodenum end in  the pancreaticoduodenal nodes present along the inside  of the curve of the duodenum, i.e. at the junction of the  pancreas and the duodenum. From here the lymph  passes partly to the hepatic nodes , and through them to  the coeliac nodes ; and partly to the superior mesenteric  nodes and ultimately via intestinal lymph trunk into the  cisterna chyli.   Some vessels from the first part of the duodenum  drain into the pyloric nodes, and through them to the  hepatic nodes. All the lymph reaching the hepatic nodes  drains into the coeliac nodes.   Sympathetic nerves from thoracic ninth and tenth spinal  segments and parasympathetic nerves from the vagus,  pass through the coeliac plexus and reach the  duodenum along its arteries.   Mucous membrane: Shows evaginations in the form of  villi and invaginations to form crypts of Lieberkuhn.  Lining of villi is of columnar cells with microvilli.  Muscularis mucosae comprises two layers.   Submucosa is full of mucus-secreting Brunner's glands.  The muscularis externa comprises outer longitudinal  and inner circular layer of muscle fibres.    * In the skiagram taken after giving a barium meal,  the first part of the duodenum is seen as a triangular  shadow called the duodenal cap (Fig. 20.14).   * The first part of the duodenum is one of the  commonest sites for peptic ulcer, possibly because  of direct exposure of this part to the acidic contents  reaching it from the stomach.   The patient is usually an over busy young person  with a tense temperament. The ulcer pain located  at the right half of epigastrium is relieved by meals  and reappears on an empty stomach.   * The first part of duodenum is overlapped by the  liver and gallbladder, either of which may become  adherent to, or even ulcerated by a duodenal ulcer.  Other clinically important relations of duodenum  are the right kidney and transverse colon (Fig. 20.9).   * Duodenal diverticula are fairly frequent. They are  seen along its concave border, generally at points  where arteries enter the duodenal wall.   * Congenital stenosis and obstruction of the second  part of the duodenum may occur at the site of the  opening of the bile duct. Other causes of obstruc¬  tion are:   b. Pressure by the superior mesenteric artery  (Fig. 20.15) on the third part of duodenum.   c. Contraction of the suspensory muscle of the  duodenum (Fig. 20.12).   For examining the jejunum and ileum, tie a pair of  ligatures around the jejunum close to the  duodenojejunal flexure and a pair around the ileum  close to the caecum. Cut through the small intestine  between each pair of ligatures and remove it by dividing  the mesentery close to the intestine.   Wash intestine with running tap water. Remove 10  cm each of jejunum and ileum and open it longitudinally.  Remove the peritoneal coat to expose the longitudinal  muscle layer.   Identify villi with a hand lens. Remove only the mucous  membrane and submucosa to see the underlying circular  muscle coat. Examine the differences between jejunum  and ileum.   The jejunum and ileum are suspended from the  posterior abdominal wall by the mesentery and.   therefore, enjoy considerable mobility. The jejunum  constitutes the upper two-fifths of the mobile part of  the small intestine, while the ileum constitutes the lower  three-fifths. The jejunum begins at the duodenojejunal    flexure. The ileum terminates at the ileocaecal junction.  The structure and functions of the jejunum and ileum  correspond to the general description of the small  intestine. The differences between the jejunum and the  ileum are given in Table 20.1.   The jejunum and ileum are supplied by branches from  the superior mesenteric artery, and are drained by  corresponding veins.   Lymph from lacteals drains into plexuses in the wall of  the gut. From there it passes into lymphatic vessels in  the mesentery. Passing through numerous lymph nodes  present in the mesentery, and along the superior  mesenteric artery, it ultimately drains into nodes  present in front of the aorta at the origin of the superior  mesenteric artery.   Sympathetic nerves are from T9-T11 segments and  parasympathetic is from vagus.   The villi here are tongue-shaped. No mucous glands or  aggregated lymphoid follicles are present in the  submucosa. Muscularis externa is same as in duodenum.  Outermost is the serous layer.   The villi are few, thin and finger-like. Collection of  lymphocytes in the form of Peyer's patches in lamina  propria extending into submucosa is a characteristic  feature.   Meckel's diverticulum is the persistent proximal part  of the vitellointestinal duct which is present in the  embryo, and which normally disappears during the 6th  week of intrauterine life. Some points of interest about  it are as follows (Figs 20.16a and b).   3 It is situated about 2 feet or 60 cm proximal to the  ileocaecal valve, attached to antimesenteric border  of the ileum.   5 Its apex may be free or may be attached to the  umbilicus, to the mesentery, or to any other  abdominal structure by a fibrous band.   Figs 20.16a and b: Meckel’s diverticulum: (a) Vitellointestinal  duct in an early embryo, and (b) Meckel’s diverticulum, the  proximal persistent part of the vitellointestinal duct   Acute inflammation of the diverticulum may  produce symptoms that resemble those of  appendicitis.   It may be involved in other diseases similar to  those of the intestine.   Locate the various parts of large intestine, beginning  from caecum, vermiform appendix, ascending,  transverse, descending and sigmoid colons and ending  with the rectum and anal canal. Identify the taenia,  haustration and appendices epiploicae. Trace the taenia  from the root of the vermiform appendix through the  ascending to the transverse colon and note the change  in their respective positions.   The large intestine extends from the ileocaecal junction  to the anus. It is about blind 1.5 m long, and is divided  into the caecum, (Latin blind pouch), the ascending colon,  right colic flexure, the transverse colon, left colic flexure,  the descending colon, the sigmoid colon, the rectum  and the anal canal. In the angle between the caecum  and the terminal part of the ileum there is a narrow  diverticulum called the vermiform appendix (Latin  attachment) (Fig. 20.17).   The general structure of large intestine is considered  first followed by its parts one by one.   The structure of the large intestine is adapted for  storage of matter reaching it from the small intestines,   and for absorption of fluid and solutes from it. The  epithelium is absorptive (columnar), but villi are absent.  Adequate lubrication for passage of its contents is  provided by numerous goblet cells scattered in the  crypts as well as on the surface of the mucous  membrane. The presence of numerous solitary  lymphatic follicles provides protection against bacteria  present in the lumen of the intestine.   1 The large intestine is wider in calibre than the small  intestine. The calibre is greatest at its commencement,  and gradually diminishes towards the rectum where  it is dilated to form the rectal ampulla just above the  anal canal.    2 The greater part of the large intestine is fixed, except  for the appendix, the transverse colon and the  sigmoid colon.   3 The longitudinal muscle coat forms only a thin layer  in this part of the gut. The greater part of it forms  three ribbon-like bands, called the taeniae coli.  Proximally the taeniae converge at the base of the  appendix, and distally they spread out on the  terminal part of the sigmoid colon to become  continuous with the longitudinal muscle coat of the  rectum. In the caecum, the ascending colon, the  descending colon and sigmoid colon and sigmoid  colon the positions of taeniae are anterior or taenia  libera; posteromedial or taenia mesocolica and  posterolateral or taenia omentalis but in the  transverse colon the corresponding positions of  taenia are inferior, posterior and superior.   One taenia, taenia libera , is placed anteriorly in the  caecum, ascending, descending and sigmoid colon,  but is placed interiorly in the transverse colon.   Second taenia, taenia mesocolica is present on the  posteromedial surface of caecum, ascending,  descending and sigmoid colon, but is placed  posteriorly on transverse colon at the site of attach¬  ment of the transverse mesocolon (Fig. 20.17).   Third taenia, taenia omentalis , is situated postero-  laterally in caecum, ascending, descending and  sigmoid colon, but is situated on the anterosuperior  surface of transverse colon where layers three and  four of greater omentum meet the transverse colon.  This change in position is due to twist in transverse  colon.   4 Since the taeniae are shorter than the circular muscle  coat, the colon is puckered and sacculated.   5 Small bags of peritoneum filled with fat, and called  the appendices epiploicae , (Greek to float on) are scattered    over the surface of the large intestine, except for the  appendix, the caecum and the rectum. These are most  numerous on the sides of the sigmoid colon and on  the posterior surface of the transverse colon.   The differences between the small and large  intestine are summarised in Table 20.2.   6 The blood supply to the colon is derived from the  marginal artery of Drummond. It is formed by colic  branches of superior and inferior mesenteric arteries  (see Fig. 21.11). Terminal branches from the marginal  artery are distributed to the intestine as long and  short vessels, vasa longa and vasa brevia. The long  arteries divide into anterior and posterior branches  close to the mesocolic taenia to pass between the  serous and muscular coats and reach the amesocolic  taeniae. They gradually pierce the muscular coat  and reach the submucosa. The anastomosis between  the two amesocolic taeniae is extremely poor. So  longitudinal incisions should be made along this  line.   Short branches arise either from the marginal artery  or from the long branches, and the majority of them  at once sink into the bowel wall at the mesocolic  border. The short and long branches together thus  provide the mesocolic region of the wall with  abundant blood supply. It is only the amesocolic  region which has scanty blood supply.   Subserous coat of long branches is intimately related  to appendices epiploicae, to which they contribute  branches. During removal of these appendages care  must be taken not to pull on them in order to avoid  traction on the subjacent vessel.   Bowel wall is weakened where it is pierced by the  vessels and at the sites of attachment of appendices  epiploicae. Mucosa may herniate in these situations    Table 20.2: Differences between the small intestine and the large intestine   7 Lymph from the large intestine passes through four  sets of lymph nodes.   a. Epicolic lymph nodes , lying on the wall of the gut  (Fig. 20.26).   b. Paracolic nodes , on the medial side of the ascending  and descending colon and near the mesocolic  border of the transverse and sigmoid colon.   d. Terminal nodes , on the superior and inferior  mesenteric vessels.   In carcinoma of the colon, the related paracolic and  intermediate lymph nodes have to be removed. Their  removal is possible only after the ligature of the main  branch of the superior or inferior mesenteric artery  along which the involved lymph nodes lie. It is  necessary, therefore, to remove a large segment of  the bowel than is actually required by the extent of  the disease, in order to avoid gangrene as a result of  interference with the blood supply. It is always wise  to remove the whole portion of the bowel supplied  by the ligated vessel.   8 The nerve supply of the large intestine, barring the  lower half of the anal canal, is both sympathetic and  parasympathetic. The midgut territory receives its  sympathetic supply from the coeliac and superior  mesenteric ganglia (Til to LI), and its para¬  sympathetic supply from the vagus. Both types of  nerves are distributed to the gut through the superior  mesenteric plexus.   The hindgut territory receives its sympathetic supply  from the lumbar sympathetic chain (LI, L2), and its  parasympathetic supply from the pelvic splanchnic  nerve (nervi erigentes), both via the superior hypogastric  and inferior mesenteric plexuses. Some parasym¬  pathetic fibres reach the colon along the posterior  abdominal wall. The ultimate distribution of nerves in  the gut is similar to that in the wall of the small intestine.   The parasympathetic nerves are motor to the large  intestine and inhibitory to the internal anal sphincter.  The sympathetic nerves are largely vasomotor, but also  motor to the internal anal sphincter, and inhibitory to  colon. Pain impulses from the gut up to the descending  colon travel through the sympathetic nerves, and from  the sigmoid colon and rectum through the pelvic  splanchnic nerves.    4 Mucoid secretion of colon is rich in antibodies of IgA  group, which protect it from invasion by micro¬  organisms.   5 The microvilli (apical tufts) of some columnar cells  serve a sensory function.    • Large intestine can be directly viewed by a  procedure called colonoscopy.   • Diverticulum is a small evagination of mucous  membrane of colon at the entry point of the  arteries. Its inflammation is called diverticulitis  (Fig. 20.18).   Incise the lateral wall of the caecum and locate the  ileocaecal orifice and its associated valve. Below the  ileocaecal valve identify the orifice of the vermiform  appendix.   Caecum is a large blind sac (Latin blind) forming the  commencement of the large intestine. It is situated in the  right iliac fossa, above the lateral half of inguinal  ligament. It communicates superiorly with ascending  colon, medially at the level of caecocolic junction with  ileum, and posteromedialiy with the appendix  (Fig. 20.19).   It is 6 cm long and 7.5 cm broad. It is one of those organs  of the body that have greater width than the length.  The other examples are the prostate, pons and pituitary.    same as that of the midgut (thoracic 11 to lumbar 1;  parasympathetic, vagus).   The caecum and appendix develop from the caecal bud  arising from the postarterial segment of the midgut loop.  The proximal part of the bud dilates to form the caecum.  The distal part remains narrow to form the appendix.  Thus initially the appendix arises from the apex of the  caecum. However, due to rapid growth of the lateral  wall of the caecum, the attachment of the appendix  shifts medially (Fig. 20.21).   The lower end of the ileum opens on the posteromedial  aspect of the caecocolic junction. The ileocaecal opening  is guarded by the ileocaecal valve (Fig. 20.22).   2 Nerves: Genitofemoral, femoral and lateral cutaneous  nerve of thigh (all of the right side).   The arterial supply of the caecum is derived from the  caecal branches of the ileocolic artery. The veins drain  into the superior mesenteric vein. The nerve supply is   1 The upper lip is horizontal and lies at the ileocolic  junction.   Figs 20.21 a and b: Development of the caecum: (a) Early stage,  and (b) later stage    Fig. 20.22: The ileocaecal valve seen after removal of the  anterior walls of the caecum and of the lower part of the  ascending colon   2 The lower lip is longer and concave, and lies at the  ileocaecal junction.   The twofrenula are formed by the fusion of the lips  at the ends of the aperture. These are the left or anterior  and the right or posterior frenula. The left end of the  aperture is rounded, and the right end narrow and  pointed.   1 The valve is actively closed by sympathetic nerves,  which cause tonic contraction of the ileocaecal  sphincter.   2 It regulates the passage of ileal contents into the  caecum, and prevents them from passing too quickly.    This is a worm-like diverticulum arising from the  posteromedial wall, of the caecum, about 2 cm below  the ileocaecal orifice (Fig. 20.22).   The length varies from 2 to 20 cm with an average of  9 cm. It is longer in children than in adults. The diameter  is about 5 mm. The lumen is quite narrow and may be  obliterated after mid-adult life.   The appendix lies in the right iliac fossa. Although the  base of the appendix is fixed, the tip can point in any  direction, as described below. The positions are often  compared to those of the hour hand of a clock  (Figs 20.23 and 20.24).   1 The appendix may pass upwards and to the right.  This is paracolic or 11 o'clock position.   2 It may lie behind the caecum or colon, known as  retrocaecal or 12 o'clock position. This is the  commonest position of appendix, about 65%.   3 The appendix may pass upwards and to the left. It  points towards the spleen. This is the splenic  or 2 o'clock position. The appendix may lie in front  of the ileum (preileal) or behind the ileum (postileal).  The postileal type is most dangerous type.   4 It may pass horizontally to the left (as if pointing to  the sacral promontory called promontoric or 3  o'clock position.   5 It may descend into the pelvis called pelvic or 4  o'clock position. This is the second most common  position about 30%.   6 It may lie below the caecum (subcaecal) and may  point towards the inguinal ligament called as  midinguinal or 6 o'clock position.   1 The appendicular orifice situated on the postero¬  medial aspect of the caecum 2 cm below the ileocaecal  orifice.   2 The appendicular orifice is occasionally guarded by  an indistinct semilunar fold of the mucous  membrane, known as the valve of Gerlach.   3 The orifice is marked on the surface by a point  situated 2 cm below the junction of transtubercular  and right lateral planes (Fig. 20.25a).   4 McBumey's point is the site of maximum tenderness  in appendicitis. The point lies at the junction of lateral  one-third and medial two-thirds of line joining the right  anterior superior iliac spine to umbilicus (Fig. 20.25b).   It is quite small and may be partially or completely  obliterated after mid-adult life.   The appendix is suspended by a small, triangular fold  of peritoneum, called the mesoappendix, or  appendicular mesentery. The fold passes upwards  behind the ileum, and is attached to the left layer of the  mesentery (Fig. 20.19).   The appendicular artery is a branch of the lower  division of the ileocolic artery. It runs behind the  terminal part of the ileum and enters the mesoappendix  at a short distance from its base. Here it gives a recurrent  branch which anastomoses with a branch of the  posterior caecal artery. The main artery runs towards  the tip of the appendix lying at first near to and then in  the free border of the mesoappendix. The terminal part  of the artery lies actually on the wall of the appendix  (Fig. 20.26).   Blood from the appendix is drained by the  appendicular, ileocolic and superior mesenteric veins,  to the portal vein.   Sympathetic nerves are derived from thoracic nine and  ten segments through the coeliac plexus. Parasym¬  pathetic nerves are derived from the vagus. Referred  pain of appendix is felt at umbilicus, similar to that of  small intestine and testis.    Figs 20.25a and b: Position of the appendix: (a) The base of the appendix is marked by a point 2 cm below the junction of the  transtubercular and right lateral planes, and (b) McBurney’s point is the site of maximum tenderness in acute appendicitis    Fig. 20.26: Arterial supply of caecum and appendix. Various  groups of lymph nodes are also seen   Most of the lymphatics pass directly to the ileocolic  nodes, but a few of them pass indirectly through the  appendicular nodes situated in the mesoappendix.   The lumen of appendix is very narrow. There are no  villi. The epithelium invaginates to form crypts of  Lieberkuhn. Muscularis mucosae is ill defined.   Submucosa reveals many lymphoid masses. That is  why it is called the abdominal tonsil Muscularis externa  comprises two layers. Outermost is the serous layer.    • Inflammation of the appendix is known as  appendicitis seen in adolescent age. In this condi¬  tion, it is usually necessary to remove the  appendix. The operation for removal of the appen¬  dix is called appendicectomy. Some anatomical facts  relevant to the diagnosis and treatment of  appendicitis are as follows.   * Pain caused by appendicitis is first felt in the  region of the umbilicus. This is referred pain. Note  the fact that both the appendix and the umbilicus  are innervated by segment T10 of the spinal cord;  appendix by sympathetic fibres and umbilicus by  somatic fibres. With increasing inflammation pain  is felt in the right iliac fossa. This is caused by  involvement of the parietal peritoneum of the  region (remember that parietal peritoneum is  sensitive to pain, but visceral peritoneum is not):  Appendicitis is common because:    iii. As the lumen is small it gets obstructed by  faecolith.   • McBurney's point is the site of maximum  tenderness in appendicitis. The point lies at the  junction of the lateral one-third and the medial  two-thirds of the line joining the umbilicus to the  right anterior superior iliac spine. It corresponds,  roughly, to the position of the base of the appendix  (Fig. 20.27). Examination of a case of acute  appendicitis reveals following physical signs.   • When the appendix is retrocaecal, extension of the  hip joint may cause pain because the appendix is  disturbed by stretching of the psoas major muscle.   * In pelvic appendicitis pain may be felt when the  thigh is flexed and medially rotated, because the  obturator internus is stretched.   * Appendicular dyspepsia: Chronic appendicitis  produces dyspepsia resembling disease of  stomach, duodenum or gallbladder. It is due to  passage of infected lymph to the subpyloric nodes  which cause irritation of pylorus. There is history  of earlier acute appendicitis.    Ascending colon is about 12.5 cm long and extends from  the caecum to the inferior surface of the right lobe of  the liver. Here it bends to the left to form the right colic  flexure. It is covered by peritoneum on three sides.   Anteriorly, it is related to the coils of small intestine,  the right edge of the greater omentum, and the anterior  abdominal wall. Posteriorly, it is related to the iliacus,  the quadratus lumborum, the transversus abdominis,  the lateral cutaneous, ilioinguinal, and iliohypogastric  nerves and the right kidney.   Right colic flexure lies at the junction of the ascending  colon and transverse colon. Here the colon bends  forwards, downwards and to the left. The flexure lies  on the lower part of right kidney. Anterosuperiorly, it  is related to the colic impression on inferior surface of  the right lobe of liver (Fig. 20.9a).    Transverse colon is about 50 cm long and extend across  the abdomen from the right colic flexure to the left colic  flexure. Actually it is not transverse, but hangs low as  a loop to a variable extent. It is suspended by the  transverse mesocolon attached to the anterior border of  pancreas, and has a wide range of mobility (Fig. 20.28).   Anteriorly , it is related to the greater omentum and  to the anterior abdominal wall. Posteriorly , it is related  to the second part of the duodenum, the head of the  pancreas, and to coils of small intestine (Table 20.3).   Left colic flexure lies at the junction of the transverse  colon and the descending colon. Here the colon bends  downwards, and backwards. The flexure lies on the  lower part of the left kidney and diaphragm, behind  the stomach, and below the anterior end of the spleen.  The flexure is attached to the eleventh rib (in the  midaxillary line) by a horizontal fold of peritoneum,  called the phrenicocolic ligament. This ligament supports  the spleen and forms a partial upper limit of the left  paracolic gutter (Table 20.4).    Descending colon is about 25 cm long and extends from  the left colic flexure to the sigmoid colon. It runs  vertically up to the iliac crest, and then inclines medially  on the iliacus and psoas major to reach the pelvic brim,  where it is continuous with the sigmoid colon. The  descending colon is narrower than the ascending colon.   Anteriorly , it is related to the coils of small intestine.  Posteriorly , it is related to the transversus abdominis,  the quadratus lumborum, the iliacus and psoas muscles;  the iliohypogastric, ilioinguinal, lateral cutaneous,  femoral and genitofemoral nerves; the gonadal and  external iliac vessels.    Fig. 20.28: Relation of transverse mesocolon to anterior border  of pancreas    Sigmoid colon is about 37.5 cm long, and extends from  the pelvic brim to the third piece of the sacrum, where    Table 20.3: The comparison between right two-thirds and left one-third of transverse coion   Arterial supply Middle colic branch of superior Ascending branch of left colic artery    Nerve supply and Branches of vagus, as Branches of pelvic splanchnic, S2, S3    it becomes the rectum. It forms a sinuous loop, and  hangs down in pelvis over the bladder and uterus.  Occasionally, it is very short, and takes a straight course.  It is suspended by the sigmoid mesocolon and is  covered by coils of small intestine.    rectum. The distal part of hindgut is dilated to form  the cloaca, which gets separated by urorectal septum  into a posterior part—the anorectal canal and an  anterior part—the primitive urogenital sinus. The  anorectal canal forms distal part of rectum and proximal  part of anal canal. Distal part of anal canal is formed  from an invagination of surface ectoderm called the  proctodeum.    It shows only invagination to form deep crypts of  Lieberkuhn. Lining epithelium is of columnar cells with  intervening goblet cells. Muscularis mucosae is well  defined.   Outer longitudinal coat is thickened at three places to  form taenia coli. Inner coat is of circular fibres.  Outermost layer is serous /adventitia.   2 inches long  2 feet from end of ileum  2 times more common in men  2% occurrence in population  2 types of tissues may be present   During rotation of stomach, the C-shaped duodenum  falls to the right. At the same time it lies against  posterior abdominal wall and gets retroperitoneal.  Duodenum develops partly from foregut and partly  from midgut. Till the origin of hepatic bud it develops  from foregut, i.e. first and upper half of second part.  The remaining two and a half parts arise from midgut.   Duodenum is supplied both by branches of coeliac  axis (artery of foregut) and by branches of superior  mesenteric artery (artery of midgut).   It gives rise to the part of duodenum distal to the  opening of bile duct, jejunum, ileum, caecum,  vermiform appendix, ascending colon, hepatic flexure  and right two-thirds of transverse colon.   Midgut is in the form of primary intestinal loop. At  the apex of the loop it is connected to the yolk sac and  grows very rapidly during 6th week, so much so that it  protrudes into the umbilical cord. This is called  physiological herniation. After an interval of 4 weeks, i.e.  at 10th week it returns back into the enlarged abdominal  cavity. During this herniation and return the midgut  loop rotates by 270° in a counter clockwise direction.   Its cranial part gives rise to left one-third of transverse  colon, descending colon, pelvic colon, proximal part of   Most of the duodenum is fixed and retroperitoneal  2nd part of duodenum contains the openings of  bile and pancreatic ducts   3rd part of duodenum is crossed anteriorly by  superior mesenteric vessels   Duodenal cap is triangular shadow of its first part  seen in Ba meal (X-ray). Transverse colon is the  most mobile part of large intestine.   Pain of early appendicitis is referred to the region  of umbilicus. The visceral peritoneum of appendix  receives supply from lesser splanchnic nerve,  arising from T10 sympathetic ganglion and T10  segment of spinal cord. Same segment receives  sensation from the umbilical area. Later  appendicitis pain is localized to right iliac fossa.  McBurney's point is a point at the junction of  medial 2/3rd and lateral l/3rd of a line joining  umbilicus to the right anterior superior iliac spine.  Ileocaecal junction is the commonest site of TB of  intestines.    A young male felt pain in the region of umbilicus.  He also had nausea, temperature and increased pulse  rate with leucocytosis. Later on the pain was localised  in right iliac fossa,   Ans: Initially the pain of acute appendicitis is referred  to the skin in the region of umbilicus. Afferent nerve  fibres from appendix are carried in lesser splanchnic  nerve to T10 segment of spinal cord. The afferent    impulses from the skin of umbilicus also reach T10  segment through 10th intercostal nerve. Since both  the somatic and visceral impulses reach the same  segment, and somatic impulses being appreciated  better by brain, the pain is referred to the skin of the  umbilicus. The most common position of appendix  is retrocaecal, and since the patient's pain is in right  iliac fossa, the position of the appendix is likely to  be retrocaecal,   McBurney's point lies at the junction of lateral one-  third and medial two-thirds of a line joining an terior  superior iliac spine to the umbilicus.    1. Which of the following is not a characteristic feature  of large intestine?   7. First 2.5 cm of 1st part of duodenum is not supplied  by:   10. Which part of intestine contains Brunner's glands?  a. Ileum b. Duodenum   l.b 2. d 3. c 4. d 5. d 6. b 7. d 8. d 9. d 10. b   The three ventral branches of the abdominal aorta are  coeliac trunk, superior mesenteric and inferior  mesenteric arteries. These are the arteries of the foregut,  midgut and hindgut, respectively. There is anastomoses  between the branches of these three main arteries.   In this chapter the coeliac trunk, the superior and  inferior mesenteric vessels, and the portal vein will be  studied.   Identify the short trunk of coeliac axis artery at the level  of the intervertebral disc between T12 and LI vertebrae  arising from the aorta. Dissect its relations especially  with the coeliac ganglion and identify its three branches  and their further divisions.   Clean the superior mesenteric vessels with its  branches both from its right and left surfaces. Dissect  these branches and trace them till the organs of their  supply.   Identify the inferior mesenteric artery arising at the  L3 vertebra. Trace its course and branches.   Identify the large portal vein formed by the union of  superior mesenteric and splenic vein posterior to the  neck of pancreas. Trace it upwards towards the remains  of free margin of lesser omentum till the porta hepatis  where it divides into two branches. Identify the veins  taking part in portosystemic anastomoses.   The coeliac trunk is the artery of the foregut (Figs 21.1  and 21.2). It supplies all derivatives of the foregut that  lie in the abdomen namely:    Fig. 21.1: Ventral and lateral branches of the abdominal aorta  with their levels of origin    1 The lower end of the oesophagus, the stomach and  upper part of the duodenum up to the opening of  the bile duct.   The coeliac trunk arises from the front of the abdominal  aorta just below the aortic opening of the diaphragm  at the level of the disc between thoracic twelve and first  lumbar vertebrae . The trunk is only about 1.25 cm long.  It ends by dividing into its three terminal branches,  namely the left gastric, common hepatic and splenic  arteries (Figs 21.3 to 21.5).    Fig. 21.2: Left view of a sagittal section through the abdominal  aorta showing the origin of its three ventral branches   1 It is surrounded by the coeliac plexus of nerves ( see  Fig. 27.6).   2 Anteriorly, it is related to the lesser sac and to the  lesser omentum (Fig. 21.2).   3 To its right, there are the right crus of the diaphragm,  the right coeliac ganglion and the caudate process  of the liver.   4 To its left, there are the left crus of the diaphragm,  the left coeliac ganglion and the cardiac end of the  stomach.   5 Interiorly, it is related to the body of the pancreas  and to the splenic vein (Fig. 21.2).   The left gastric artery is the smallest of the three branches   of the coeliac trunk. It runs upwards to the left behind    the lesser sac to reach the cardiac end of the stomach  where it turns forwards and enters the lesser omentum  to run downwards along the lesser curvature of the  stomach. It ends by anastomosing with the right gastric  artery.   a. Two or three oesophageal branches at the cardiac end  of the stomach.   b. Numerous gastric branches along the lesser  curvature of the stomach (Fig. 21.4).   The common hepatic artery runs downwards, forwards  and to the right, behind the lesser sac to reach the  upper border of the duodenum. Here it enters the  lesser omentum. It then run upwards as proper hepatic  artery in the right free margin of the lesser omentum,  in front of the portal vein, and to the left of the bile  duct (see Figs 18.10 and 21.3). Reaching the porta  hepatis it terminates by dividing into right and left  hepatic branches.   1 The gastroduodenal artery is a large branch which  arises at the upper border of the first part of the  duodenum. The part of the hepatic artery till the  origin of the gastroduodenal artery is called the  common hepatic artery . The part distal to it is the proper  hepatic artery.   The gastroduodenal artery runs downwards  behind the first part of the duodenum and divides  at its lower border into the right gastroepiploic and  superior pancreaticoduodenal arteries.   The right gastroepiploic artery enters the greater  omentum, follows the greater curvature of the  stomach, and anastomoses with the left gastro¬  epiploic artery.   The superior pancreaticoduodenal artery (often  represented by two arteries anterior and posterior)  runs downwards in the pancreaticoduodenal groove,  and ends by anastomosing with the inferior  pancreaticoduodenal artery, a branch of the superior  mesenteric.   2 The right gastric artery is a small branch which arises  from the proper hepatic artery close to the  gastroduodenal artery. It runs to the left along the  lesser curvature and ends by anastomosing with the  left gastric artery.   3 The cystic artery is a branch of the right hepatic artery.  It passes behind the common hepatic and cystic ducts  to reach the upper surface of the neck of the gall  bladder where it divides into superficial and deep  branches for the inferior and superior surfaces of the  gallbladder, respectively.   Fig. 21.4: Arteries arising from the branches of the coeiiac trunk   The splenic artery is the largest branch of the coeiiac  trunk. It runs horizontally to the left along the upper  border of the pancreas behind the lesser sac. It crosses  the left suprarenal gland and the upper part of the left  kidney to enter the lienorenal ligament, through which  it reaches the hilum of spleen where it divides into 5 to  7 splenic branches ( see Figs 19.10, 21.3 and 21.4).    1 Lower part of the duodenum below the opening of  the bile duct (Fig. 21.5).   8 Lower half of the head of the pancreas (Figs 21.2 and   1 Numerous pancreatic branches which supply the body  and tail of the pancreas. One of the branches to the  body of the pancreas is large and is known as the  arteria pancreatica magna. Another large branch to the  tail is known as the arteria caudae pancreatis. These  large arteries anastomose (on the back of the  pancreas) with the left branch of a dorsal artery which  may arise from one of the following arteries: superior  mesenteric, middle colic, hepatic, or coeiiac.   2 Five to seven short gastric arteries arise from the  terminal part of the splenic artery, run in the  gastrosplenic ligament, and supply the fundus of the  stomach.   3 The left gastroepiploic artery also arises from  the terminal part of the splenic artery, runs  downwards in the greater omentum, follows the  greater curvature of the stomach, and ends by  anastomosing with the right gastroepiploic artery.  As the name suggests the gastroepiploic arteries  supply both the stomach and greater omentum.   The superior mesenteric artery arises from the front of  the abdominal aorta, behind the body of the pancreas,  at the level of vertebra LI, one centimeter below the  coeiiac trunk (Fig. 21.5). It runs downwards and to the  right, forming a curve with its convexity towards the  left.   At its origin it lies first behind the body of the  pancreas and then in front of the uncinate process. Next  it crosses the third part of the duodenum, enters the  root of mesentery, and runs between its two layers. It  terminates in the right iliac fossa by anastomosing with  a branch of the ileocolic artery.   1 Anteriorly, it is related to the body of the pancreas  and to the splenic vein.   2 Posteriorly, to the aorta, the left renal vein, the  (Fig. 21.6a).   The superior mesenteric artery is the artery of the  midgut. It supplies all derivatives of the midgut,  namely:    mesenteric vein which lies on its right side. The artery  is surrounded by the superior mesenteric plexus of  nerves (Figs 21.6b and c).   The superior mesenteric artery gives off five sets of  branches both from its right and left sides (Fig. 21.7).   2 Those arising from its left side are 12-15 jejunal and  ileal branches.   Inferior pancreaticoduodenal artery arises from the  superior mesenteric artery at the upper border of the  third part of the duodenum. The artery soon divides  into anterior and posterior branches which run in the  pancreaticoduodenal groove, supply the head of the  pancreas and the duodenum, and ends by  anastomosing with the superior pancreaticoduodenal  artery.   Middle colic artery arises from the right side of the  superior mesenteric artery just below the pancreas. It  runs downwards and forwards in the transverse  mesocolon. It divides into a right branch, which  anastomoses with the right colic artery, and a left  branch, which anastomoses with the left colic artery.  Further branches arising from these, form arcades and  supply the transverse colon.   Right colic artery arises near the middle of the concavity  of the superior mesenteric artery. It passes to the right  behind the peritoneum, and at the upper part of the  ascending colon it divides into a descending branch,  which anastomoses with the ileocolic artery, and an  ascending branch, which anastomoses with the middle  colic artery. The branches form an arch, from the  convexity of which smaller branches are distributed to  the upper two-thirds of the ascending colon and the  right flexure of the colon.   Ileocolic artery arises from the right side of the superior  mesenteric artery. It runs downwards and to the right,  and divides into superior and inferior branches. The  superior branch anastomoses with the right colic artery,  and the inferior branch anastomoses with the  termination of the superior mesenteric artery.   b. Anterior and posterior caecal branches to the  caecum (see Fig. 20.26).   c. An appendicular branch which passes behind the  ileum and reaches the appendix through its  mesentery (see Fig. 20.26).   d. The ileal branch to the terminal portion of the  ileum.   Jejunal and ileal branches are about 12 to 15 in number  and arise from the left side of the superior mesenteric  artery. They run between the two layers of the   Figs 21 .6a to c: Relation of the superior mesenteric artery: (a) Left view of a sagittal section through the aorta, (b) anterior view of the  vessel after removal of the duodenum and pancreas, and (c) anterior view of the vessel with the duodenum and pancreas in place    mesentery towards the gut. They anastomose with  one another to form arterial arcades which give off  straight branches or vasa recta to the gut. These  branches supply the jejunum (Fig. 21.8a) and most of  ileum (Fig. 21.8b). The terminal part of the ileum is  supplied by the ileocolic artery.   On passing from jejunum to ileum, the number of  arterial arcades increases from one to as many as five.  The vasa recta are longer and less numerous in the  jejunum than in the ileum. These are distributed  alternately to opposite surfaces of the gut, and the  neighbouring vessels do not anastomose with one  another.   1 Superior mesenteric vein is a large vein which drains  blood from the small intestine, the appendix, the  caecum, the ascending colon and the transverse colon  (Fig. 21.9).   2 It begins in the right iliac fossa by the union of  tributaries from the ileocaecal region. It accompanies    Figs 21,8a and b: Arterial arcades and vasa recta of: (a) Jejunum,  and (b) ileum   5 The upper part of the anal canal, above the anal  valves.    the superior mesenteric artery. The vein lies on the  right side of the artery. It terminates, behind the neck  of the pancreas, by joining the splenic vein to form  the portal vein.   a. Veins corresponding to the branches of the  superior mesenteric artery.    • Sudden occlusion of the superior mesenteric  artery, vein or both may occur due to embolism  or thrombosis. It is usually followed by a rapidly  spreading form of intestinal obstruction due to the  haemorrhagic infarction of the involved gut.   • Superior mesenteric artery crosses third part of  duodenum (see Fig. 20.15). This part of duodenum  may get obstructed as it lies between abdominal  aorta and superior mesenteric artery. Duodenum  behaves like a nut between the two tongs formed  by these two arteries.   The inferior mesenteric artery is the artery of the  hindgut. It supplies the parts of the gut that are deri¬  vatives of the hindgut and posterior part of cloaca, the  anorectal canal, namely:   Inferior mesenteric artery arises from the front of the  abdominal aorta behind the third part of the duodenum,  at the level of third lumbar vertebra, and 3 to 4 cm above  the bifurcation of the aorta.   It runs downwards and to the left, behind the peri¬  toneum, crosses the common iliac artery medial to the  left ureter, and continues in the sigmoid mesocolon as  the superior rectal artery (Fig. 21.9).   The inferior mesenteric artery gives off the left colic,  sigmoid branches (Fig. 21.10).   Left colic artery is the first branch of the inferior  mesenteric artery. It runs upwards and to the left,  behind the peritoneum of the posterior wall of the left  infracolic compartment and after a variable course  divides into an ascending and a descending branch. The  ascending branch enters the transverse mesocolon and  anastomoses with the middle colic artery. The  descending branch anastomoses with the highest  sigmoid artery. They form a part of the marginal artery  from which branches are distributed to the left one-third  of the transverse colon and to the descending colon  (Fig. 21.10).   Sigmoid arteries are 2 to 4 in number. They pass  downwards and to the left, and anastomose with each    other to form the lower part of the marginal artery. The  uppermost branch anastomoses with the descending  branch of the left colic artery, whereas the lowest  sigmoid artery sends a branch to anastomose with the  superior rectal artery. They supply the descending  colon in the iliac fossa and the sigmoid colon.   Superior rectal artery is the continuation of the inferior  mesenteric artery beyond the root of the sigmoid  mesocolon, i.e. over the left common iliac vessels. It  descends in the sigmoid mesocolon to reach the rectum.  Opposite third sacral vertebra it divides into right and  left branches which descend one on each side of the  rectum. They pierce the muscular coat of the rectum  and divide into several branches, which anastomose  with one another at the level of the anal sphincter to  form loops around the lower end of the rectum. These  branches communicate with the middle and inferior  rectal arteries in the submucosa of the anal canal  (Figs 21.10 and 21.16).   1 The inferior mesenteric vein drains blood from the  rectum, the anal canal, the sigmoid colon and the  descending colon.   2 It begins as the superior rectal vein from the upper  part of the internal rectal venous plexus. In the plexus  it communicates with the middle and inferior rectal  veins. The superior rectal vein crosses the left  common iliac vessels medial to the left ureter and  continues upwards as the inferior mesenteric vein.    This vein lies lateral to the inferior mesenteric artery.  The vein ascends behind the peritoneum, passes  lateral to the duodenojejunal flexure and behind the  body of the pancreas. It opens into the splenic vein  (Fig. 21.9).   3 Its tributaries correspond to the branches of the  inferior mesenteric artery.    Inferior mesenteric vein lies in the free margin of  paraduodenal fold before draining into splenic vein.  In case of strangulated internal hernia in  duodenojejunal recess these folds may be cut to  enlarge the space. One needs to remember that  inferior mesenteric vein (not the artery) lies in the  fold, and it needs to be ligated (see Fig. 18.32).   Marginal artery was described by von Haller in 1803  and its present name was given by Sudeck in 1907. The  marginal artery is an arterial arcade situated along the  concavity of the colon. It is formed by anastomoses  between the main arteries supplying the colon, namely  the ileocolic, right colic, middle colic, left colic and  sigmoid arteries. It lies at a distance of 2.5 to 3.8 cm  from the colon. It is closest to the colon in its descending  and sigmoid parts. Vasa recta arise from the marginal  artery and supply the colon (Fig. 21.11).   The marginal artery is capable of supplying the colon  even in the absence of one of the main feeding trunks.  This fact is utilized in surgery. However, at the  junctional points between the main vessels, there may  be variations in the competence of the anastomoses.   4 The spleen, and conveys it to the liver. In the liver,  the portal vein breaks up into sinusoids which are  drained by the hepatic veins to the inferior vena cava  (Figs 21.12 and 21.13).   It is called the portal vein because its main tributary,  the superior mesenteric vein, begins in one set of  capillaries (in the gut) and the portal vein ends in  another set of capillaries in the liver.    The portal vein is about 8 cm long. It is formed by the  union of the superior mesenteric and splenic veins  behind the neck of the pancreas at the level of second  lumbar vertebra. Inferior mesenteric vein drains into  splenic vein.   It runs upwards and a little to the right, first behind  the neck of the pancreas, next behind the first part of  the duodenum, and lastly in the right free margin of  the lesser omentum.   The blood flow in portal vein is slow. Blood of  superior mesenteric vein drains into right lobe. Blood  of splenic and inferior mesenteric vein drains into left  lobe. This is called "streamline flow".   The portal vein can thus be divided into infra-  duodenal, retroduodenal and supraduodenal parts.   The vein ends at the right end of the porta hepatis by  dividing into right and left branches which enter the  liver.   2 Bile duct (within free margin of the lesser omentum).  Posteriorly   Inferior vena cava, separated by epiploic foramen ( see  Fig. 18.10).   After entering the liver, each branch divides and  redivides along with the hepatic artery to end  ultimately in the hepatic sinusoids, where the portal  venous blood mixes with the hepatic arterial blood.   1 The right branch is shorter and wider than the left  branch. After receiving the cystic vein, it enters the  right lobe of the liver (Fig. 21.16).   2 The left branch is longer and narrower than the right  branch. It traverses the porta hepatis from its right  end to the left end, and furnishes branches to the  caudate and quadrate lobes. Just before entering the  left lobe of the liver, it receives:   The left gastric vein accompanies the corresponding  artery. At the cardiac end of the stomach it receives a  few oesophageal veins. The right gastric vein accom¬  panies the corresponding artery. It receives the  prepyloric vein.   The paraumbilical veins are small veins that run in  the falciform ligament, along the ligamentum teres, and  establish anastomoses between the veins of the anterior  abdominal wall present around the umbilicus and the  portal vein (Fig. 21.16).   These communications form important routes of  collateral circulation in portal obstruction. The  tributaries of portal and systemic system are put in  Table 21.1. Various sites of portosystemic anastomoses  are put in Table 21.2 and Fig. 21.17.    * Portal pressure: Normal pressure in the portal vein  is about 5-15 mm Hg. It is usually measured by  splenic puncture and recording the intrasplenic  pressure.   * Portal hypertension (pressure above 40 mm Hg): It  can be caused by the following.   a. Cirrhosis of liver, in which the vascular bed of  liver is markedly obliterated.   i. Caput medusae around the umbilicus,  which is of diagnostic value to the clinician  (see Fig. 16.5b).   ii. Oesophageal varices at the lower end of  oesophagus which may rupture and cause  dangerous or even fatal haematemesis (see  Fig. 19.4).   iii. Haemorrhoids in the anal canal may be  responsible for repeated bleeding felt per  rectum (see Fig. 33.9).   In cases of cirrhosis of liver, sometimes a shunt  operation is done, where one of the main portal  channels (splenic, superior mesenteric, or portal  vein) is directly anastomosed with either inferior  vena cava or the left renal vein (Fig. 21.18).   * Since the blood flow in portal vein is slow, and  streamlined, the toxic infective substances  absorbed from small intestine pass via the superior  mesenteric vein into the right lobe of liver leading    to toxic changes or amoebic abscess in right lobe.  The blood lacking in amino acids, etc. which is  absorbed via the inferior mesenteric vein affect  the left lobe, leading to its fibrosis or cirrhosis  (Fig. 21.19).   • The lower end oesophagus is one of the sites of  portocaval anastomoses. Some oesophageal veins  drain into left gastric vein and then into portal  vein. Other oesophageal veins drain into  hemiazygos and then into vena azygos and  superior vena cava. In liver cirrhosis portal vein  pressure is raised, leading to oesophageal varices,  which may rupture leading to haematemesis (see  Fig. 19.4).   1 Infraduodenal part, from a part of the left vitelline  vein distal to the dorsal anastomosis.    2 Retroduodenal part, from the dorsal anastomosis  between the two vitelline veins.   3 Supraduodenal part, from the cranial part of the right  vitelline vein.    * Coeliac trunk is the first short unpaired ventral  visceral branch of the abdominal aorta which  supplies structures derived from the foregut.   * Superior mesenteric and inferior mesenteric  arteries supply structures derived from midgut  and hindgut respectively.   * Inferior mesenteric vein lies in the free margin of  paraduodenal recess and is not accompanied by  its artery in this region.   * Branches of portal vein anastomose with the  branches of systemic circulation at few places.   * Portal vein supplies 80% blood to liver, while  hepatic artery gives 20%.    Fig. 21.16: Important sites of communication of portal and systemic veins: (1) Lower end of oesophagus, (2) around umbilicus, and  (3) anal canal    Few paraumbilical veins run along ligamentum  teres and left branch of portal vein (Fig. 21.16).  Veins around umbilicus drain via superior and  inferior epigastric veins into superior and inferior  vena cava respectively.   Superior rectal vein continues up as inferior  mesenteric vein which drains into portal vein.  The middle and inferior rectal veins drain into  inferior vena cava (Figs 21.16 and 21.17).   Central veins and sublobular veins are part of  portal circulation. Intercostal veins and phrenic  veins end in systemic circulation.   It joins left branch of portal vein to inferior vena  cava.    In liver cirrhosis the paraumbilical  veins open up to transfer portal venous  blood into systemic circulation. It result  in caput medusae (see Fig. 16.5b)   Liver cirrhosis causes anastomoses  between superior rectal and other rectal  veins. These anastomosing veins result  in piles or haemorrhoids   Fig. 21.18: Shunt operation between left renal vein and portal  vein    A middle aged alcoholic patient complained of lot  of blood in his vomit.   Ans: The lower end of oesophagus is one of the sites  of portocaval anastomoses. Some oesophageal veins  drain into left gastric vein and then into portal vein.  Other oesophageal veins drain into hemiazygos and  then into vena azygos and superior vena cava.   In liver cirrhosis, portal vein pressure is raised,  leading to oesophageal varices, which may rupture  leading to blood in the vomit.   Normally the anastomoses between tributaries of  portal vein and those of superior vena cava is very  little. These anastomotic channels develop in an  attempt to take portal blood into caval blood.   2. Which of the following is not a direct branch of  coeliac trunk?   a. Right hepatic b. Left hepatic  c. Coeliac trunk d. Common hepatic   a. Ileocolic artery b. Middle colic artery  c. Right colic artery d. Jejunal branches   L c 2. d 3. a 4. b 5. c 6, b 7. b 8. c 9. c 10. c   The extrahepatic biliary apparatus collects bile from  the liver, stores it in the gallbladder, and transmits it  to the 2nd part of duodenum.   Locate the porta hepatis on the inferior surface of liver.  Look for two hepatic ducts there. Follow them till these  join to form common hepatic duct. Identify cystic duct  and usually green-coloured gallbladder.   See the point of junction of cystic duct with common  hepatic duct and the formation of bile duct. Trace the  bile duct in relation to the duodenum. Its opening has  been seen in dissection of the duodenum.   Trace the cystic artery supplying gallbladder, cystic  duct, hepatic ducts and upper part of bile duct.   The right and left hepatic ducts emerge at the porta  hepatis from the right and left lobes of the liver. The  arrangement of structures at the porta hepatis from  behind forwards is:   It is formed by the union of the right and left hepatic  ducts near the right end of the porta hepatis. It runs    downwards for about 3 cm and is joined on its right  side at an acute angle by the cystic duct to form the bile  duct.   Accessory hepatic ducts are present in about 15% of  subjects. They usually issue from the right lobe of the  liver, and terminate either in the gallbladder, or in the  common hepatic duct anywhere in its course, or even  in the upper part of the bile duct (Fig. 22.3).   They are responsible for oozing of bile from the  wound after cholecystectomy. Therefore, it is always  better to use a drain to avoid retention of bile in the  depths of the wound.   Gallbladder is a pear-shaped reservoir of bile situated  in a fossa on the inferior surface of the right lobe of the  liver. The fossa for the gallbladder extends from the  right end of the porta hepatis to the inferior border of  the liver (Figs 22.1 and 22.4).   The gallbladder is 7 to 10 cm long, 3 cm broad at its  widest part, and about 30 to 50 ml in capacity.   Th e fundus projects beyond the inferior border of the  liver, in the angle between the lateral border of the right  rectus abdominis and the ninth costal cartilage. It is  entirely surrounded by peritoneum, and is related  anteriorly to the anterior abdominal wall, and  posteriorly to the beginning of the transverse colon.   The body lies in the fossa for the gallbladder on the  liver. The upper narrow end of the body is continuous  with the neck at the right end of the porta hepatis. The  superior surface of the body is devoid of peritoneum,  and is adherent to the liver. The inferior surface is  covered with peritoneum, and is related to the  beginning of the transverse colon and to the first and  second parts of the duodenum (Fig. 22.5a).   The neck is the narrow upper end of the gallbladder.  It is situated near the right end of the porta hepatis. It  first curves anterosuperiorly and then posteroinferiorly  to become continuous with the cystic duct. Its  junction with the cystic duct is marked by a constriction  (Fig. 22.5a).   Superiorly, the neck is attached to the liver by areolar  tissue in which the cystic vessels are embedded.  Interiorly, it is related to the first part of the duodenum.  The mucous membrane of the neck is folded spirally to  prevent any obstruction to the inflow or outflow of bile.  The posteromedial wall of the neck is dilated outwards  to form a pouch called the Hartmann's pouch which is  directed downwards and backwards. Gallstones may  lodge in this pouch (Fig. 22.5b).    Cystic duct is about 3 to 4 cm long. It begins at the  neck of the gallbladder, runs downwards, backwards  and to the left, and ends by joining the common hepatic  duct at an acute angle to form the bile duct. The mucous  membrane of the cystic duct forms a series of 5 to 12  crescentic folds, arranged spirally to form the so-called  spiral valve of Heister. This is not a true valve (Fig. 22.6).   1 Storage of bile, and its release into the duodenum  when required.   2 Absorption of water, and concentration of bile. Bile  may be concentrated as much as ten times.   3 The normal gallbladder also absorbs small amounts  of a loose bile salt-cholesterol compound. When the  gallbladder is inflamed, the concentration function    Fig. 22.4: Location of the gallbladder on the inferior surface of  the right lobe of the liver    becomes abnormal and the bile salts alone are  absorbed leaving cholesterol behind. Bile salts have    Figs 22.5a and b: Relations of the gallbladder: (a) Anterior view after removal of the liver, and (b) left view of sagittal section  through the gallbladder fossa including the Calot’s triangle   3 Then it lies behind, or embedded in, the head of  pancreas infraduodenal part;   4 Near the middle of the left side of the second part of  the duodenum it comes in contact with the pancreatic  duct and accompanies it through the wall of the  duodenum, the infraduodenal part .    a powerful solvent action on cholesterol which tends  to be precipitated. This can lead to the formation of  the gallstones.   4 It regulates pressure in the biliary system by  appropriate dilatation or contraction. Thus the normal,  choledocho-duodenal mechanism is maintained.   Bile duct is formed by the union of the cystic and   common hepatic ducts near the porta hepatis. It is 8 cm   1 The bile duct runs downwards and backwards, first  in the free margin of the lesser omentum,  supraduodenal part;   2 Behind the first part of the duodenum the retro-  duodenal part;   1 Anteriorly: A groove in the upper and lateral parts of  the posterior surface of the head of the pancreas.   The course of the duct through the duodenal wall is  very oblique. Within the wall the two ducts usually  unite to form the hepatopancreatic ampulla , or ampulla of  Vater. The distal constricted end of the ampulla opens  at the summit of the major duodenal papilla 8 to 10 cm  distal to the pylorus ( see Fig. 23.16).   The terminal part of the bile duct is surrounded just  above its junction with the pancreatic duct by a ring of  smooth muscle that forms the sphincter choledochus  (choledochus = bile duct). This sphincter is always  present. It normally keeps the lower end of the bile duct  closed (Fig. 22.7). As a result, bile formed in the liver  keeps accumulating in the gallbladder and also  undergoes considerable concentration. When food  enters the duodenum, specially a fatty meal, the  sphincter opens and bile stored in the gallbladder is  poured into the duodenum. Another less developed  sphincter, which is usually but not always present  around the terminal part of the pancreatic duct is the  sphincter pancreaticus . A third sphincter surrounds the  hepatopancreatic ampulla and is called the sphincter  ampullae or sphincter of Oddi.   1 The cystic artery is the chief source of the blood  supply, and is distributed to the gallbladder, the  cystic duct, the hepatic ducts and the upper part of  the bile duct (Fig. 22.8).    Fig. 22.7: Sphincters in the region of the junction of the bile duct  and the main pancreatic duct with the duodenum    2 Several branches from the posterior superior  pancreaticoduodenal artery supply the lower part  of the bile duct.   3 The right hepatic artery forms a minor source of  supply to the middle part of the bile duct.   The cystic artery usually arises from the right hepatic  artery, passes behind the common hepatic and cystic  ducts, and reaches the upper surface of the neck of the  gallbladder, where it divides into superficial and deep  branches.   1 The superior surface of the gallbladder is drained  by veins which enter the liver through the fossa for  the gallbladder and join tributaries of hepatic veins.   2 The rest of the gallbladder is drained by one or two  cystic veins which open into the right branch of the  portal vein (see Fig. 21.15).   3 The lower part of the bile duct drains into the portal  vein.   1 Lymphatics from the gallbladder, the cystic duct, the  hepatic ducts and the upper part of the bile duct pass  to the cystic node and to the node of the anterior border of  the epiploic foramen. These are the most constant  members of the upper hepatic nodes. The cystic node  lies in the angle between the cystic and common  hepatic ducts; it is constantly enlarged in cholecystitis  (Fig. 22.5b).   2 The lower part of the bile duct drains into the lower  hepatic and upper pancreaticosplenic nodes.   The cystic plexus of nerves, supplying the territory of  the cystic artery, is derived from the hepatic plexus,  which receives fibres from the coeliac plexus, the left  and right vagi and the right phrenic nerves. The lower  part of the bile duct is supplied by the nerve plexus  over the superior pancreaticoduodenal artery.   Parasympathetic nerves are motor to the musculature  of the gallbladder and bile ducts, but inhibitory to the  sphincters. Sympathetic nerves from thoracic seven to  nine are vasomotor and motor to the sphincters.   Pain from the gallbladder may travel along the  vagus, the sympathetic nerves, or along the phrenic  nerves. It may be referred to different sites through  these nerves as follows.   b. Through the sympathetic nerves to the inferior  angle of the right scapula. Lateral horn of thoracic  7 segment of spinal cord gives sympathetic fibres  to coeliac ganglion through greater splanchnic  nerve. T7 segment receives pain fibres from skin   over inferior angle of scapula. So visceral pain is  referred to somatic area.   c. Through the phrenic nerve to the right shoulder  (C4 gives fibres to phrenic nerve and supra¬  clavicular nerves).    * Biliary obstruction arises when passage of bile into  the duodenum is blocked either completely or  partially.   a. The gallstones which slip down into the bile  5 duct and block it (Fig. 22.10).   b. Cancer of the head of pancreas which com¬  presses the bile duct.   In these cases since bile pigments will not reach  the duodenum, faeces will be light-colored.  Instead bile pigments reach the blood, causing  jaundice and as these are excreted in urine, cause  it to be dark-coloured. Combination of light-  coloured stools with dark-coloured urine implies  obstructive jaundice. If it is associated with  episodes of pain, it is likely to be due to gallstones.  If it is associated with loss of weight, etc. it is likely  to be due to cancer of head of pancreas.   * Bile duct can be assessed from the duodenum by  a procedure—endoscopic retrograde cholangio¬  graphy (ERCP).   ■ Referred pain: Pain of stretch of CBD or gallbladder  is referred to epigastrium. It is also referred to right  shoulder and inferior angle of right scapula  (Fig. 22.9).   * Humoral control of the gallbladder: The gallbladder  contracts when food rich in fat enters the  duodenum. The fat causes certain cells in  duodenum to liberate a hormone called chole-  cystokinin-pancreozymin. The hormone is carried to  the gallbladder and causes its contraction. It also  causes dilatation of the sphincters.   * Inflammation of the gallbladder is called  cholecystitis . The patient complains of pain over  the right hypochondrium radiating to the inferior  angle of the right scapula, or to right shoulder.  When a finger is placed just below the costal  margin, at the tip of the 9th costal cartilage, the  patient feels sharp pain on inspiration. He winces  with a "catch" in his breath. This is referred to as  Murphy's sign (Fig. 22.11).   * Stones may form in the gallbladder. The condition  is called cholelithiasis (Fig, 22.12). They typically    occur in fat, fertile, female of forty (but also in  males). The stones are responsible for the time to  time spasmodic pain called biliary colic. In these  cases, Murphy's sign is of great diagnostic value.  Gallstones never develop in dog, cat, sheep, rabbit  because of high fatty acid content of their bile.  Stones are common in man, ox and hog because  of low fatty acid in them. They can give rise to  severe spasmodic pain which is called biliary colic.   * The region of the gallbladder is frequently  operated upon. It is, therefore, necessary for the  surgeon to be aware of the numerous variations  that may exist in the extrahepatic biliary  apparatus, and in the related blood vessels. The  operation for removal of the gallbladder is called  cholecystectomy.   * The most significant lesions of typhoid fever occur  in lymphoid tissue, bone marrow and gallbladder.  Gallbladder is invariably infected in these cases,  and the carrier state may be due to persistence of  typhoid bacilli in this organ.   * Courvoisier's law: Dilatation of the gallbladder  occurs only in extrinsic obstruction of the bile duct  like pressure by carcinoma of head of pancreas.  Intrinsic obstruction by stones do not cause any  dilatation because of associated fibrosis.   * Gallbladder is related to duodenum. The gall¬  stones may penetrate wall of gallbladder and  duodenum to get into the lumen of duodenum.  These stones travel through the coils of small  intestine and may block the narrow ileocaecal  junction leading to intestinal obstruction.   * Calot's triangle: Triangular space formed by cystic  duct, common hepatic duct and segment-V of right  hemiliver forms Calot's triangle. This space contains  cystic artery, cystic lymph node and autonomic  fibres reaching the gallbladder (Fig. 22.5b)    Fig. 22.9 : Sites of referred pain due to stretch of bile duct or  gallstone    Mucous membrane: It is projected to form folds.  Epithelium consists of a single layer of tall columnar  cells. Lamina propria contains loose connective tissue.    The fibromuscular coat: It consists of smooth muscle  fibres and collagen fibres which rests on an outer  fibroareolar coat.   Hepatic bud arises from the endoderm of caudal part  of foregut. The bud elongates cranially. It gives rise to  a small bud on its right side. This is called pars cystica  and the main part is pars hepatica. Pars cystica forms the  gallbladder and the cystic duct, which drains into the  common hepatic duct (CHD). Pars hepatica forms CHD  and divides into right and left hepatic ducts. These  ducts reach septum transversum and proliferate to form  the hepatic parenchyma. The entire epithelium is  endodermal and other layers are of splanchnic origin.    ■ Gallbladder stores as well as concentrates bile. So  it is more liable to have gallstones.   * There is lot of variability in the origin of cystic  artery as well as in the pattern of joining of cystic  duct. This has to be kept in mind during surgery  of this region.   • Pain of cholecystitis may be referred to epigastrium,  right shoulder and inferior angle of right scapula.   A fat fair fertile female complains of spasmodic pain  in her right hypochondrium radiating to epigastrium  and right shoulder.   • What is the reason for pain in right hypo¬  chondrium?   Ans: The reason for pain is cholecystitis which may  or may not be associated with multiple gallstones.   Pain of foregut derived structures is referred to  epigastric region, so pain of cholecystitis is referred  there. Epigastric region is supplied by T7-T9 nerves.  The same nerves gives white ramus comm unicans to  T7-T9 sympathetic ganglia. From these ganglia fibres  of greater splanchnic nerve arise, which relay in coeliac  ganglion to supply extrahepatic biliary apparatus.  Since sympathetic and spinal fibres arise from same  segments and reach same segments, pain impulses of  viscera is referred to somatic areas.   Right coeliac plexus is joined by right phrenic  nerve (C3, C4). It supplies the peritoneum overlying  gallbladder. Since peritoneum is inflamed, the  impulses are carried to supraclavicular nerves also  (C3, C4). So pain is referred to right shoulder.   During cholecystectomy by open surgery, the  surgeon noticed severe bleeding. The bleeding was  quickly stopped by treating the bleeding vessel by  electrocautery.   • What other surgical procedures are available to  remove the gallbladder?    Ans: The bleeding of cystic artery can be stopped by  compressing the proper hepatic artery between the  thumb and index finger, as it lies in the anterior wall  of the epiploic foramen.   Cystic artery is a branch of the proper hepatic  artery and was treated by electrocautery.   a. Right hepatic b. Left hepatic  c. Coeliac trunk d. Common hepatic   5. Bile duct runs in relation to which part of the  duodenum?   Spleen (Greek splen and Latin Lien) is a lymphatic organ  connected to the blood vascular system. It acts as a filter  for blood and plays an important role in the immune  responses of the body.   Locate the spleen situated deep in the left  hypochondrium. The gastrophrenic ligament has  already been cut during removal of stomach. Now cut  through the posteriorly placed lienorenal ligament taking  care of the splenic vessels contained therein. See the  close relation of spleen to the left costodiaphragmatic  recess and the left lung.   Identify the viscera related to the spleen, e.g.  stomach, tail of pancreas, left kidney and splenic flexure  of colon.   Trace the branches of splenic artery into the  substance of spleen as far as possible.   Cut the phrenicocolic ligament of peritoneum and  deliver the spleen from the abdominal cavity.   The spleen (Latin low spirits) is a wedge-shaped organ  lying mainly in the left hypochondrium, and partly in  the epigastrium. It is wedged in between the fundus of  the stomach and the diaphragm. The spleen is  tetrahedral in shape (Figs 23.1a and b).   The spleen is soft, highly vascular and dark purple in  colour. The size and weight of the spleen are markedly  variable. On an average the spleen is 1 inch or 2.5 cm  thick, 3 inches or 7.5 cm broad, 5 inches or 12.5 cm long.    7 ounces in weight, and is related to 9th to 11th ribs.  The odd numbers are 1, 3,5 are 7,9,11. Normally, the  spleen is not palpable.   The spleen lies obliquely along the long axis of the 10th  rib. Thus it is directed downwards, forwards and  laterally, making an angle of about 45 degrees with the  horizontal plane (Fig. 23.2).   The spleen has two ends, three borders and two surfaces  (Fig. 23.3) and 2 angles and hilum.   The anterior or lateral end is expanded and is more like a  border. It is directed downwards and forwards, and  reaches the midaxillary line.   The posterior or medial end is rounded. It is directed  upwards, backwards and medially, and rests on the  upper pole of the left kidney.   The intermediate border is also rounded and is directed  to the right.   Anterobasal angle: It is the junction of superior border  with lateral or anterior end. It is the most forward  projecting part of spleen. When spleen is enlarged, this    Figs 23.1a and b: Location of the spleen: (a) In relation to the nine regions of the abdomen: (1) Epigastrium; (2) umbilical region;  and (3) hypogastrium, and (b) in relation to the fundus of the stomach and the diaphragm    Fig. 23.2: The axis of the spleen corresponds to the long axis  of the 10th rib of the left side; it makes an angle of about 45°  with the horizontal plane   is felt first, so this is called as "clinical angle of spleen.  Posterobasal angle: Junction of inferior border with  lateral or anterior end of spleen.   1 The gastrosplenic ligament extends from the hilum of  the spleen to the greater curvature of the stomach. It  contains the short gastric vessels and associated  lymphatics and sympathetic nerves (see Figs 18.18  and 23.4).   2 The lienorenal ligament extends from the hilum of the  spleen to the anterior surface of the left kidney. It  contains the tail of the pancreas, the splenic vessels,  and associated pancreaticosplenic lymph nodes,  lymphatics and sympathetic nerves.   3 The phrenicocolic ligament is not attached to the spleen,  but supports its anterior end. It is a horizontal fold  of peritoneum extending from the splenic flexure of    Fig. 23.4: Peritoneal ligaments attached to the spleen, and  common sites of accessory spleen    colon to the diaphragm opposite the 11th rib in the  midaxillary line. It limits the upper end of the left  paracolic gutter ( see Fig. 18.28).   The visceral surface is related to the fundus of the  stomach, the anterior surface of the left kidney, the  splenic flexure of the colon and the tail of the pancreas  (Fig-23.5).   The gastric impression , for the fundus of the stomach,  lies between the superior and intermediate borders. It  is the largest and most concave impression on the  spleen (Fig. 23.5).   The renal impression , for the left kidney, lies between  the inferior and intermediate borders.   The colic impressions , for the splenic flexure of the  colon, occupies a triangular area adjoining the anterior  end of the spleen. Its lower part is related to the  phrenicocolic ligament.   The pancreatic impression , for the tail of the pancreas,  lies between the hilum and the colic impression.   The hilum lies on the inferomedial part of the gastric  impression along the long axis of the spleen. It transmits  the splenic vessels and nerves, and provides attachment  to the gastrosplenic and lienorenal ligaments.   The diaphragmatic surface is related to the diaphragm  which separates the spleen from the costodiaphrag¬  matic recess of pleura, lung and 9th, 10th and 11th ribs  of the left side (Fig. 23.6).    reach the hilum of the spleen where it divides into five  or more branches. These branches enter the spleen to  supply it.   Within the spleen it divides repeatedly to form  successfully the straight vessels called penicilli, which  further divide into ellipsoids and arterial capillaries.  Further course of the blood is controversial. According  to closed theory of splenic circulation, the capillaries are  continuous with the venous sinusoids that lie in the  red pulp; the sinusoids join together to form veins.   However, according to open theory of splenic  circulation, the capillaries end by opening into the red  pulp from where the blood enters the sinusoids through  their walls.   Still others believe in a compromise theory, where the  circulation is open in distended spleen and closed in  contracted spleen. The splenic circulation is adapted  for the mechanism of separation and storage of the red  blood cells.   On the basis of its blood supply, the spleen is said  to have superior and inferior vascular segments. The  two segments are separated by an avascular plane  (Fig. 23.4). Each segment may be subdivided into one  to two disc-like middle segments and a cap-like pole  segment. Apart from its terminal branches, the splenic  artery gives off:    The spleen is supplied by the splenic artery which is  the largest branch of the coeliac trunk. The artery is  tortuous in its course to allow for movements of the  spleen. It passes through the lienorenal ligament to   The splenic vein is formed at the hilum of the spleen. It  runs a straight course behind the pancreas. It joins the    superior mesenteric vein behind the neck of the  pancreas to form the portal vein. Its tributaries are the  short gastric, left gastroepiploic, pancreatic and inferior  mesenteric veins (Fig. 23.7).   Splenic tissue proper has no lymphatics. A few  lymphatics arise from the connective tissue of the  capsule and trabeculae and drain into the pancreatico-  splenic lymph nodes situated along the splenic artery.   Sympathetic fibres are derived from the coeliac plexus.  They are vasomotor in nature. They also supply some  smooth muscle present in the capsule.   1 Phagocytosis: The spleen is an important component  of the reticuloendothelial system. The splenic  phagocytes include:   a. The reticular cells and free macrophages of the red  pulp.   c. Free macrophages and endothelial cells of the  venous sinusoids, and   d. Surface reticular cells of the lymphatic follicle. The  phagocytes present in the organ remove cell debris  and old and effete RBCs, other blood cells and  microorganisms, and thus filter the blood.  Phagocytosis of circulating antigens initiates  humoral and cellular immune responses.   2 Haemopoiesis: The spleen is an important haemo-  poietic organ during foetal life. Lymphopoiesis  continues throughout life. The lymphocytes  manufactured in it take part in immune responses  of the body.   In the adult spleen, haemopoiesis can restart in  certain diseases, like chronic myeloid leukaemia and  myelosclerosis.    3 Immune responses: Under antigenic stimulation, there  occurs increased lymphopoiesis for cellular  responses, and increased formation of plasma cells  for the humoral responses.   4 Storage of RBCs: Red blood cells can be stored in the  spleen and released into the circulation when  needed. This function is better marked in animals  than in man.   Histologically, spleen is made up of the following four  component parts.   1 Supporting fibroelastic tissue, forming the capsule,  coarse trabeculae and a fine reticulum. In human,  the smooth muscle cells in the capsule and trabeculae  are few, and the contraction and distension of spleen  are attributed to constriction or relaxation of the  blood vessels, which regulate the blood flow in the  organ.   2 White pulp consisting of lymphatic nodules arranged  around an arteriole called Malpighian corpuscle  (Fig. 23.8).   3 Red pulp is formed by the collection of cells in the  interstices of reticulum, in between the sinusoids.  The cell population includes:   b. All three types of blood cells (RBC, WBC and  platelets), and   c. The fixed and free macrophages. Lymphocytes are  freely transformed into plasma cells which can  produce large amounts of antibodies the  immunoglobulins.   Spleen develops in the mesoderm in the cephalic part  of left layer of dorsal mesogastrium. The development  occurs during sixth week of intrauterine life. Number  of nodules develop which soon fuse to form a lobulated  spleen ( see Fig. 18.6). Notching of the superior border  of the adult spleen is an evidence of its multiple origin.  These nodules which fail to fuse, form accessory spleens  Figure 23.4 shows the usual sites of accessory spleens.   1 In the derivatives of the dorsal mesogastrium, i.e.  gastrosplenic ligament, lienorenal ligament,  gastrophrenic ligament and greater omentum.    • Palpation of the spleen: A normal spleen is not  palpable. An enlarged spleen can be felt under the  left costal margin during inspiration. Palpation is  assisted by turning the patient to his right side.  Note that the spleen becomes palpable only after  it has enlarged to about twice its normal size.   • Splenomegaly: Enlargement of the spleen is called  splenomegaly (Fig. 23.9). It may occur in a number  of diseases. Sometimes the spleen becomes very  large. It then projects towards the right iliac fossa  in the direction of the axis of the tenth rib.   * Splenectomy: Surgical removal of the spleen is  called splenectomy. During this operation damage  to the tail of the pancreas has to be carefully  avoided, as the tail of pancreas is very rich in islets  of Langerhans. Spleen has 2 pedicles, gastrosplenic  and lienorenal. Their contents are separated  carefully before the ligaments are cut (Fig, 23.10).   ■ Splenic puncture: Spleen can be punctured through  the 8th or 9th intercostal space in the midaxillary  line using a lumbar puncture needle. When  enlarged, it can be punctured through the  midaxillary line. To avoid laceration of spleen, the  patient must hold his breath during the procedure,  Intrasplenic pressure is an indirect record of the  portal pressure. Splenic venography reveals and  confirms the enlarged portosystemic communi¬  cations in cases of portal hypertension.   * Splenic infarction: The smaller branches of splenic  artery are end arteries. Their obstruction  (embolism) therefore, results in splenic infarction  which causes referred pain in the left shoulder  (Kehr's sign) (Fig. 23.9).   ■ Spleen is in danger of trauma to the left lower  thoracic cage especially 9,10,11th ribs. A ruptured    spleen may cause severe haemorrhage, as it has a  rich blood supply.   * Referred pain: Pain of splenic tissue is poorly  localised. It is also referred to the epigastrium.  Stretch of the splenic capsule produces localized  pain in the posterior part of left upper quadrant  (hypochondrium).   * Spleen: If there is a small tear in the spleen, It can  be sutured with catgut and the greater omentum  can be wrapped round the sutured tear.   ■ Partial splenectomy: Since there are segmental  branches of the splenic artery, only one segment  can be removed according to the state of spleen.   * After splenectomy, spleen can be cut into small  pieces and these can be implanted within the  greater omentum. Because of vascularization,  spleen survives and does its function of producing  the antibodies.   Identify the pancreas—a retroperitoneal organ lying  transversely across the posterior abdominal wall.   Head is easily identifiable in the concavity of  duodenum. Uncinate process of the head is the part  behind the upper part of superior mesenteric artery.   Portal vein is formed behind its neck. Rest of the  part extending to the left is its body and tail reaching till  the hilum of spleen.   Turn the descending part of the duodenum and the  head of the pancreas to the left. Look for the posterior  pancreaticoduodenal vessels and the bile duct on the  head of the pancreas.   Expose the structures posterior to pancreas. Turn  the tail and body of the pancreas to the right stripping  the splenic artery and vein from its posterior surface  and identify the vessels passing to the gland from them.   On the posterior surface of the pancreas, make a  cut into the gland parallel to and close to the superior  and inferior margins of the body. Pick away the lobules  of the gland between the cuts to expose the greyish  white duct and the interlobular ducts draining into the  main duct.   The pancreas ( pan = all; kreas = flesh) is a gland that is  partly exocrine and partly endocrine. The exocrine part  secretes the digestive pancreatic juice; and the  endocrine part secretes hormones, e.g. insulin. It is soft,  lobulated and elongated organ.   The pancreas lies more or less transversely across the  posterior abdominal wall, at the level of first and second  lumbar vertebrae.   It is J-shaped or retort-shaped, set obliquely. The  bowl of the retort represents its head, and the stem of  the retort, its neck, body and tail. It is about 15-20 cm  long, 2.S-3.8 cm broad and 1.2-1.8 cm thick and weighs  about 90 g.   The pancreas is divided (from right to left) into head,  neck, body and the tail. The head is enlarged and lies  within the concavity of the duodenum. The tail reaches  the hilum of the spleen (Fig. 23.11). The entire organ  lies posterior to the stomach separated from it by the  lesser sac ( see Figs 18.17 and 18.18).   Head is the enlarged flattened right end of pancreas,  situated within the "C-shaped" curve of the duodenum.   The head has three borders , superior, inferior and right  lateral; two surfaces , anterior and posterior; and one  process , called the uncinate process, which projects  from the lower and left part of the head towards the  left (Fig. 23.11).   The superior border is overlapped by the first part of the  duodenum and is related to the superior pan¬  creaticoduodenal artery (Fig. 23.11). The inferior border  is related to the third part of the duodenum and to the  inferior pancreaticoduodenal artery. The right lateral  border is related to the second part of the duodenum,  the terminal part of the bile duct and the anastomosis  between the two pancreaticoduodenal arteries.    Fig. 23.10: Two pedicles of spleen to be cut during splenectomy. Referred pain of spleen reaches the left shoulder    Figs 23.12a and b: (a) Anterior, and (b) posterior relations of the head of the pancreas   3 Jejunum which is separated from it by peritoneum  (Fig. 23.12a).   4 Bile duct which runs downwards and to the right  and is often embedded in the substance of pancreas  (Fig. 23.12b).    Figs 23.13a and b: Relations of the neck of the pancreas:  (a) Anterior, and (b) posterior relations    It is related anteriorly to the superior mesenteric vessels,  and posteriorly to the aorta (Fig. 23.12a).   This is the slightly constricted part of the pancreas  between its head and body. It is directed forwards,  upwards and to the left. It has two surfaces, anterior  and posterior.   The anterior surface is related to: (1) The peritoneum  covering the posterior wall of the lesser sac, and (2) the  pylorus (Fig. 23.13a).   The posterior surface is related to the termination of  the superior mesenteric vein and the beginning of the  portal vein (Fig. 23.13b).   The body of the pancreas is elongated. It extends from  its neck to the tail. It passes towards the left with a slight  upward and backward inclination.   It is triangular on cross-section, and has three borders  (anterior, superior and inferior). A part of the body  projects upwards beyond the rest of the superior  border, a little to the left of the neck. This projection is  known as the tuber omentale.   The anterior border provides attachment to the root of  the transverse mesocolon. The superior border is related  to coeliac trunk over the tuber omentale, the hepatic  artery to the right, and the splenic artery to the left  (see Fig. 21.3). The inferior border is related to the superior  mesenteric vessels at its right end (Fig. 23.14).   The anterior surface is concave and is directed forwards  and upwards. It is covered by peritoneum, and is  related to the lesser sac and to the stomach.    Fig. 23.14: Anterior and inferior relations of the body of the  pancreas    The posterior surface is devoid of peritoneum, and is  related to:   a. The aorta with the origin of the superior  mesenteric artery.   The inferior surface is covered by peritoneum, and is  related to the duodenojejunal flexure, coils of jejunum  and the left colic flexure (Fig. 23.14).   This is the left end of the pancreas. It lies in the  lienorenal ligament together with the splenic vessels.  It comes into contact with the lower part of the gastric  surface of the spleen (Figs 23.4 and 23.5).   The exocrine pancreas is drained by two ducts, main  and accessory (Fig. 23.16).    Inferior vena cava Superior mesenteric artery  Fig. 23.15: Posterior relations of the body of the pancreas    1 The main pancreatic duct of Wirsung lies near the  posterior surface of the pancreas and is recognised  easily by its white colour. It begins at the tail; runs  towards the right through the body; and bends at  the neck to run downwards, backwards and to the  right in the head.   3 It receives many small tributaries which join it at  right angles to its long axis forming what has been  described as a herring bone pattern.   4 Within the head of the pancreas the pancreatic duct  is related to the bile duct which lies on its right side.  The two ducts enter the wall of the second part of  the duodenum, and join to form the hepatopancreatic  ampulla of Vater which opens by a narrow mouth on  the summit of the major duodenal papilla , 8 to 10 cm  distal to the pylorus.   5 The accessory pancreatic duct of Santorini begins in the  lower part of the head, crosses the front of the main  duct with which it communicates and opens into the  duodenum at the minor duodenal papilla. The  papilla of accessory pancreatic duct is situated 6 to  8 cm distal to the pylorus. The opening of the  accessory duct lies cranial and ventral to that of the  main duct. The two ducts remind the double origin of  pancreas from the ventral and dorsal pancreatic  buds.   Veins drain into splenic, superior mesenteric and portal  veins (Fig. 23.18).   Lymphatics follow the arteries and drain into the  pancreaticosplenic, coeliac and superior mesenteric  groups of lymph nodes.   The vagus or parasympathetic and splanchnic  sympathetic nerves supply the pancreas through the  plexuses around its arteries.   Sympathetic nerves are vasomotor. Parasympathetic  nerves control pancreatic secretion. Secretion is also  influenced by the hormone cholecystokinin produced  by cells in the duodenal epithelium. The pancreatic juice  contains various enzymes that help in the digestion of  proteins, carbohydrates and fats.   1 Digestive: Pancreatic juice contains many digestive  enzymes of which the important ones are as follows:  Trypsin breaks down proteins to lower peptides.  Amylase hydrolyses starch and glycogen to  disaccharides. Lipase breaks down fat into fatty acids  and glycerol.   2 Endocrine: Carbohydrates are the immediate source  of energy. Insulin helps in utilizations of sugar in  the cells. Deficiency of insulin results in hyper-  glycaemia. The disease is called diabetes mellitus. There  appears to be poverty in plenty.   3 Pancreatic juice: It provides appropriate alkaline  medium (pH 8) for the activity of the pancreatic  enzymes.   1 The exocrine part is a serous gland, made up of  tubular acini lined by pyramidal cells with basal  round nuclei, containing zymogen granules. It  secretes the digestive pancreatic juice.   2 The endocrine part of pancreas is made up of  microscopic elements called the pancreatic islets of  Langerhans. These are small isolated masses of cells  distributed throughout the pancreas. They are  most numerous in the tail. The islets have various  types of cells the most important of which are the  beta cells which are granular and basophilic, forming  about 80% of the cell population. They produce  insulin. Other types of cells are alpha cells with  subtype A1 and A2. These are granular and  acidophilic and form about 20% of the cell  population. A1 cells belong to enterochromaffin  group and secrete pancreatic gastrin and serotonin.  A2 cells secrete glucagon (Fig. 23.19).   It arises as a larger dorsal bud and a smaller ventral  bud. These soon fuse to form the pancreas. Ventral bud  forms uncinate process and an inferior part of head of  pancreas. The dorsal bud forms part of the head, whole  of neck, body and tail of pancreas.   The duct of ventral bud taps the duct of dorsal  pancreatic bud near its neck and opens into the  duodenum as the main pancreatic duct. The proximal  part of duct of dorsal pancreatic bud forms the  accessory pancreatic duct (Figs 23.20a to c).   a. An annular pancreas encircling the second part of  the duodenum. An annular pancreas may be the  cause of duodenal obstruction.   b. Accessory pancreatic tissue may be present at various  sites. These include the wall of the duodenum,  the jejunum, the ileum, or of Meckel's diverticulum.   Figs 23.20a to c: Stages (a, b and c) of development of pancreas    c. Inversion of pancreatic ducts: In this condition, the  accessory duct is larger than the main duct, and  the main drainage of the pancreas is through the  minor duodenal papilla.   • Carcinoma is common in the head of the pancreas.  Pressure over the posteriorly placed bile duct leads  to persistent obstructive jaundice. It may press upon  the portal vein, causing ascites; or may involve the  stomach, causing pyloric obstruction.   • Acute pancreatitis is a serious disease. It may be a  complication of mumps.   • Pancreatic cyst presents as a large fixed tumour in  the upper part of abdomen along the median plane.  They are often symptomless.   • Pancreatic pain is felt in the back as well as in the  front of abdomen.   • Pancreatitis results in collection of fluid in the lesser  sac—a pseudocyst of pancreas.   • Annular pancreas is a developmental anomaly  where a ring of pancreatic tissue surrounds and  obstructs the duodenum.   • Pain from pancreatitis; This pain is poorly localized.  Pain is referred to epigastrium. Pain is also referred  to posterior paravertebral region and around the  lower thoracic vertebrae, due to inflammation of soft  tissues of retroperitoneum. Their afferents are being  sent through lower intercostal nerves.   • Pancreatitis: It may be primary or may be due to  gallstones in the common bile duct.   • Superior mesenteric vessels are lying behind body of  pancreas and in front of its uncinate process  (Fig. 23.14). Pancreatitis may cause inflammatory  aneurysm of the artery and/or thrombosis of the vein.   • Since pancreas has profuse blood supply, it is prone  to haemorrhage (Fig. 23.17). Blood can appear in the  flanks or in the groins. It may also enter bare area  of liver to run forward in the falciform ligament and  reach around umbilicus.   • Acute pancreatitis may cause gastric stasis and  vomiting. The autonomic supply to midgut may be  affected resulting in paralytic ileus.   • Sometimes fluid resulting from pancreatic  inflammation may collect in the lesser sac of  peritoneum, called as pseudocyst. It needs to be  drained.   • Pancreas resection: It is a difficult and complicated  procedure. Only resection of its head and neck is  possible.   Pull the liver downwards and divide the anterior layers  of the coronary and left triangular ligaments.   Identify the inferior vena cava between the liver and  the diaphragm and separate the liver downwards from  inferior vena cava. If the inferior vena cava happens to  be deeply buried in the liver, divide it and remove a  segment with the liver.   Expose the structures in the porta hepatis and follow  them to their entry into the liver. Identify the viscera  related to the inferior surface of the liver and see their  demarcations on the liver.   Explore the extent of right and left pleural cavities  and pericardium related to the superior and anterior  surfaces of liver, though separated from it by the  diaphragm.   Cut the structures close to the porta hepatis and  separate all the peritoneal ligaments and folds of the liver.   Remove the liver from the body. Identify its various  borders, surfaces, lobes.   The liver is a large, solid, gland situated in the right  upper quadrant of the abdominal cavity. In the living  subject, the liver is reddish brown in colour, soft in  consistency, and very friable. It weighs about 1600 g in  males and about 1300 g in females.   The liver occupies the whole of the right hypo-  chondrium, the greater part of the epigastrium, and  extends into the left hypochondrium reaching up to the  left lateral line. From the above it will be obvious that  most of the liver is covered by ribs and costal cartilages,  except in the upper part of the epigastrium where it is  in contact with the anterior abdominal wall (Fig. 23.21).   The liver is the largest gland in the body. It secretes  bile and performs various other metabolic functions.   The liver is also called the 'hepar' from which we  have the adjective 'hepatic' applied to many structures  connected with the organ.   The liver is wedge-shaped. It resembles a four-sided  pyramid laid on one side (Fig. 23.22).    Fig. 23.22: Comparison of the orientation of the surfaces of the  liver to those of a four-sided pyramid   Out of these the inferior surface is well defined  because it is demarcated, anteriorly, by a sharp inferior  border. The other surfaces are more or less continuous  with each other and are imperfectly separated from one  another by ill-defined, rounded borders.   The inferior border is sharp anteriorly where it separates  the anterior surface from the inferior surface. It is  somewhat rounded laterally where it separates the right  surface from the inferior surface. The sharp anterior  part is marked by:   a. An interlobar notch or the notch for the ligamentum  teres.   b. A cystic notch for the fundus of the gallbladder  (Fig. 23.23).   In the epigastrium, the inferior border extends from  the left 8th costal cartilage to the right 9th costal  cartilage.   The liver is divided into right and left lobes by the  attachment of the falciform ligament anteriorly and  superiorly; by the fissure for the ligamentum teres  inferiorly; and by the fissure for the ligamentum venosum  posteriorly.   The right lobe is much larger than the left lobe, and  forms five sixth of the liver. It contributes to all the five  surfaces of the liver, and presents the caudate and  quadrate lobes.   The caudate lobe is situated on the posterior surface.  It is bounded on the right by the groove for the inferior  vena cava, on the left by the fissure for the ligamentum  venosum, and inferiorly by the porta hepatis. Above it is  continuous with the superior surface. Below and to the  right, just behind the porta hepatis, it is connected to  the right lobe of the liver by the caudate process  (Fig. 23.24). Below and to the left it presents a small  rounded elevation called the papillary process.   The quadrate lobe is situated on the inferior surface,  and is rectangular in shape. It is bounded anteriorly by  the inferior border, posteriorly by the porta hepatis, on  the right by the fossa for the gallbladder, and on the left  by the fissure for the ligamentum teres (Fig. 23.24).   The porta hepatis is a deep, transverse fissure about  5 cm long, situated on the inferior surface of the right  lobe of the liver. It lies between the caudate lobe above  and the quadrate lobe below and in front. The portal  vein, the hepatic artery and the hepatic plexus of nerves  enter the liver through the porta hepatis, while the right  and left hepatic ducts and a few lymphatics leave it. The  relations within; the porta hepatis are from behind  forwards are the portal vein, the hepatic artery and the  hepatic ducts. The lips of the porta hepatis provide  attachment to the lesser omentum (Fig. 23.24).   The left lobe of the liver is much smaller than the right  lobe and forms only one-sixth of the liver. It is flattened  from above downwards. Near the fissure for the  ligamentum venosum, its inferior surface presents a  rounded elevation, called the omental tuberosity or tuber  omentale.   Caudate I  Fissure for ligamentum venosum  Papillary process  Caudate process  Hepatic duct-  Ligamentum teres-  Quadrate lobe-  Gallbladder  Inferior layer of coronary ligament-   Most of the liver is covered by peritoneum. The areas  not covered by peritoneum are as follows.   1 A triangular bare area , on the posterior surface of the  right lobe, limited by the superior and inferior layers  of the coronary ligament and by the right triangular  ligament.   2 The groove for the inferior vena cava f on the posterior  surface of the right lobe of the liver, between the  caudate lobe and the bare area.   3 The fossa for the gallbladder which lies on the inferior  surface of the right lobe to the right of the quadrate  lobe.   The anterior surface is triangular and slightly convex.  It is related to the xiphoid process and to the anterior  abdominal wall in the median plane; and to diaphragm  on each side. The diaphragm separates this surface from  the pleura above the level of a line drawn from the  xiphisternal joint to the 10th rib in the midaxillary line;  and from the lung above the level of a line from the  same joint to the 8th rib. The falciform ligament is  attached to this surface a little to the right of the median  plane (Figs 23.23 and 23.31).   The posterior surface is triangular. Its middle part  shows a deep concavity for the vertebral column. Other  relations are as follows.   1 The bare area is related to the diaphragm; and to the  right suprarenal gland near the lower end of the  groove for the inferior vena cava.    2 The groove for the inferior vena cava lodges the upper  part of the vessel, and its floor is pierced by the  hepatic veins.   3 The caudate lobe lies in the superior recess of the lesser  sac. It is related to the crura of the diaphragm above  the aortic opening, to the right inferior phrenic artery,  and to the coeliac trunk.   4 The fissure for the ligamentum venosum is very deep  and extends to the front of the caudate lobe. It  contains two layers of the lesser omentum. The  ligamentum venosum lies on its floor. The  ligamentum venosum is a remnant of the ductus  venosus of foetal life; it is connected below to the  left branch of the portal vein, and above to the left  hepatic vein near its entry into the inferior vena cava  (Fig. 23.24).   5 The posterior surface of the left lobe is marked by the  oesophageal impression (Fig. 23.25).   The superior surface is quadrilateral and shows a  concavity in the middle. This is the cardiac impression.  On each side of the impression the surface is convex to  fit the dome of the diaphragm. The diaphragm  separates this surface from the pericardium and the  heart in the middle; and from pleura and lung on each  side (Fig. 23.30).   The inferior surface is quadrilateral and is directed  downwards, backwards and to the left. It is marked by  impressions for neighbouring viscera as follows.   1 On the inferior surface of the left lobe there is a large  concave gastric impression (Fig. 23.25). The left lobe  also bears a raised area that comes in contact with  the lesser omentum: it is called the omentale tuber.   2 The fissure for the ligamentum teres passes from the  inferior border to the left end of the porta hepatis.   Oesophageal impression  Inferior vena cava  Gastric area  Tuber omentale  Ligamentum teres   3 The quadrate lobe is related to the lesser omentum,  the pylorus, and the first part of the duodenum.  When the stomach is empty the quadrate lobe is  related to the first part of the duodenum and to a  part of the transverse colon.   4 The fossa for the gallbladder lies to the right of the  quadrate lobe (Fig. 23.25).   5 To the right of this fossa the inferior surface of the  right lobe bears the colic impression for the hepatic  flexure of the colon, the renal impression for the right  kidney, and the duodenal impression for the second  part of the duodenum.   The right surface is quadrilateral and convex. It is  related to the diaphragm opposite the 7th to 11th ribs  in the midaxillary line. It is separated by the diaphragm  from the pleura up to the 10th rib, and from the lung  up to the 8th rib. Thus, the upper one-third of the  surface is related to the diaphragm, the pleura and the  lung; the middle one-third, to the diaphragm and the  costodiaphragmatic recess of the pleura; and the lower  one-third to the diaphragm alone (Fig. 23.30).   The liver receives 20% of its blood supply through the  hepatic artery, and 80% through the portal vein. Before  entering the liver, both the hepatic artery and the portal  vein divide into right and left branches. Within the liver,  they redivide to form segmental vessels which further  divide to form interlobular vessels which run in the  portal canals. Further ramifications of the interlobular  branches open into the hepatic sinusoids. Thus the  hepatic arterial blood mixes with the portal venous  blood in the sinusoids. There are no anastomoses  between adjoining hepatic arterial territories and hence  each branch is an end artery.   Hepatic sinusoids drain into interlobular veins, which  join to form sublobular veins. These in turn unite to  form the hepatic veins which drain directly into the  inferior vena cava. These veins provide great support  to the liver, besides the intra-abdominal pressure.   The hepatic veins are arranged in two groups, upper  and lower. The upper group consists of three large veins  right, left and middle, which emerge through the upper  part of the groove for the inferior vena cava, and open  directly into the vena cava. These veins keep the liver  suspended. The lower group consists of a variable  number of small veins from the right lobe and the  caudate lobe which emerge through the lower part of  the caval groove and open into the vena cava.   Microscopically the tributaries of hepatic veins, i.e.  central veins are seen as separate channels from those  of the portal radicles.   The superficial lymphatics of the liver run on the surface  of the organ beneath the peritoneum, and terminate in  caval, hepatic, paracardial and coeliac lymph nodes.  Some vessels from the coronary ligament may directly  join the thoracic duct.   The deep lymphatics end partly in the nodes around  the end of the inferior vena cava, and partly in the  hepatic nodes.   The liver receives its nerve supply from the hepatic  plexus which contains both sympathetic and  parasympathetic or vagal fibres. Nerves also reach the  liver through its various peritoneal ligaments.   On the basis of the intrahepatic distribution of the  hepatic artery, the portal vein and the biliary ducts, the  liver can be divided into the right and left functional    Figs 23.26a to d: The segments (physiological lobes) of  lobe, and (d) scheme of the left lobe   the liver, (a) Anterior aspect, (b) inferior aspect, (c) scheme of the right    lobes. These do not correspond to the anatomical lobes  of the liver. The physiological lobes are separated by a  plane passing on the anterosuperior surface along a line  joining the cystic notch to the groove for the inferior  vena cava. On the inferior surface the plane passes  through the fossa for the gallbladder; and on the  posterior surface it passes through the middle of the  caudate lobe (Figs 23.26a to d).   The right lobe is subdivided into anterior and  posterior segments, and the left lobe into medial  and lateral segments. Thus there are four segments  (Fig. 23.27) in the liver.   The hepatic segments are of surgical importance. The  hepatic veins tend to be intersegmental in their course.    3 Excretion of drugs, toxins, poisons, cholesterol, bile  pigments and heavy metals;   4 Protective by conjugation, destruction, phagocytosis,  antibody formation and excretion; and   Liver is covered by Glisson's capsule. In the pig there  are hexagonal lobules with portal radicles at  3-5 corners. Each radicle contains bile ductule, branch  each of portal vein and hepatic artery. Central vein lies  in the centre and all around the central vein are the  hepatocytes in form of laminae. On one side of the  lamina is the sinusoid and on the other side is a bile  canaliculus.   Portal lobule seen in human is triangular in shape  with three central veins at the sides and portal tract in  the centre.   The liver acinus is defined as the liver parenchyma  around a preterminal branch of hepatic arteriole  between two adjacent central veins. The liver acinus is  the functional unit of liver. Blood reaches the acinus  via branches of portal vein and hepatic artery to open  into the sinusoids to reach the central vein. On the other  hand, the flow of bile is along bile canaliculi, bile  ductules and the interlobular bile ducts. Hepatocytes  in zone I close to preterminal branch are better supplied  by oxygen, nutrients and toxins. The liver cells in zone  III close to central veins are relatively hypoxic while  cells in zone II are intermediate in oxygen supply.   Histology of the liver can be studied by liver biopsy  (Figs 23.28a and b) which is done from right lateral  surface.   From the caudal end of foregut, an endodermal hepatic  bud arises during 3rd week of development. The bud  elongates cranially. It gives rise to a small bud on its  right side. This is called pars cystica and the main part  is pars hepatica. Pars cystica forms the gallbladder and  the cystic duct which drains into common hepatic duct  (CHD).    Figs 23.28a and b: Histology of liver, (a) Portal lobule, and (b) liver acinus    The epithelial cells of pars hepatica proliferate to  form the parenchyma. These cells mix up with umbilical  and vitelline veins to form hepatic sinusoids.   Kupffer's cells and blood cells are formed from the  mesoderm of septum transversum.    • In the infrasternal angle, the liver is readily  accessible to examination on percussion, though it  is normally not palpable due to the normal tone of  the recti muscles and the softness of the liver.  Normally in the median plane the inferior border  of the liver lies on the transpyloric plane, about a  hand's breadth below the xiphisternal joint. In  women and children this border usually lies at a  slightly lower level and tends to project downwards  for a short distance below the right costal margin.  It enlarges towards right iliac fossa (Fig. 23.29).  Spleen also enlarges towards right iliac fossa.   • Inflammation of the liver is referred to as hepatitis.  It may be infective hepatitis or amoebic hepatitis.   • Under certain conditions, e.g. malnutrition, liver  tissue undergoes fibrosis and shrinks. This is  called cirrhosis of the liver.   • Liver biopsy needs to be done in certain clinical  conditions. Liver biopsy needle is passed through  right 9th intercostal space. It traverses both pleural  and peritoneal cavities (Fig. 23.30).   • Liver is the common site of metastatic tumours.  Venous blood from GIT with primary tumour  drains via portal vein into the liver.    • Liver receives blood from hepatic artery and  portal vein. Both these vessels lie in the free  margin of lesser omentum. Bleeding from the  liver can be stopped by compressing the free edge  of lesser omentum. This is called Pringles  manoeuvre. If bleeding still continues it is likely  that inferior vena cava is also injured.   • Liver resection: Liver resection for primary and  secondary tumours is done commonly. 80% of  liver mass can be removed safely. Liver can  regrow to its original size within 6-12 months after  resection. Major resections follow the planes  between segments and are anatomical.   • Liver transplantation: It can be done in patients  with end stage liver disease. The implant of the  graft requires an inferior caval anastomoses,  followed by anastomosis of the portal vein.  Finally the arterial and biliary anastomoses are  performed.   • Sometimes a right hemiliver comprising segments  V to segments VIII can be removed from a healthy  donor and transplanted into the needy patient.   • Liver cirrhosis causes "caput medusae" at the  umbilicus (Fig. 23.31).   Spleen: dimensions,, weight, surface anatomy  " 1 , 3 , 5 , 7 , 9 , 11 "   Spleen dimensions are 1 inch thick, 3 inches wide,  5 inches long.   From posterior to anterior side—VAD  V - Portal vein  A - Hepatic artery  D - Hepatic duct    • Spleen is a collection of lymphoid tissue with lot  of blood vessels.   • In case of rupture of spleen it may be removed.  Before cutting the lineorenal ligament, the tail of  pancreas and splenic vessels need to be identified  and not be injured.   • Spleen moves up and down with respiration. It is  mesodermal in origin.   • Pancreas mainly develops from dorsal pancreatic  bud. Only a part of head and its uncinate process  develops from the ventral pancreatic bud.   • Islets of Langerhans are maximum in tail of a  pancreas   • Portal vein is formed by the union of splenic and  superior mesenteric veins behind the neck of  pancreas.   • Liver is the largest gland of the body. Liver is kept  in position by the upper and lower groups hepatic  veins which drain into the inferior vena cava.   • The bare area of liver is one of the sites of porto¬  systemic anastomoses.   • The spleen also enlarges downwards and obliquely  towards right iliac fossa. It is prevented from  descending to left side by phrenico-colic ligament.    A young boy is kicked by his class mate in left upper  abdomen. The boy faints due to internal bleeding.   Arts: The young boy's spleen got ruptured leading  to internal bleeding. The treatment is to remove the  spleen, known as splenectomy.   The surgeon has to free the spleen from the  ligaments. These being gastrosplenic and lienorenal  ligaments. The lienorenal ligament contains splenic  artery, splenic vein and tail of pancreas. These  structures have to be identified, pulled out of the  ligament, before incising the ligament for removal  of spleen. The gastrosplenic ligament contains short  gastric vessels which also have to be separated before  incising the ligament.   2. Accessory pancreatic duct is also called as:  a, Wirsung duct b. Santorini duct   4. Which of the following structures is not present in  the free margin of lesser omentum?   a. Tail of pancreas b. Splenic vein  c. Splenic artery d. Renal vein   7. Which of the following glands has the presence of  centro-acinar cells?   a. Greater omentum b. Falciform ligament  c. Lesser omentum d. Ligamentum teres   10. Ligamentum teres is attached to one of the  following veins:   1. c 2, b 3. b 4. b 5. d 6. b 7, a 8. a 9. c 10. b   The closely packed structure and numerous functions  of the kidney illustrate the beautiful workmanship of  our Creator. It not only applies to the kidney but to each  and every part of our body.   Remove the fat and fascia from the anterior surface of  left and right kidneys and suprarenal glands. Find left  suprarenal vein and left testicular or ovarian vein and  trace both to left renal vein. Follow this vein from the  left kidney to inferior vena cava and note its tributaries.  Displace the vein and expose left renal artery, follow its  branches to the left suprarenal gland and ureter. Follow  the ureter in abdomen.   Identify the structures related to the anterior surface  of both the kidneys. Turn the left kidney medially to  expose its posterior surface and note the relation of its  vessels and the ureter. Identify the muscles, vessels  and nerves which are posterior to the kidneys.   Carry out the same dissection on the right side. Note  that the right testicular or ovarian and suprarenal veins  drain directly into the inferior vena cava.   Cut through the convex border of the kidney till the  hilus. Look at its interior. Identify the cortex, pyramids  and calyces.   Follow the ureters in the renal pelvis, in the abdomen,  in the pelvic cavity and finally through the wall of urinary  bladder.   The kidneys are also called renes from which we have  the derivative renal ; and nephros from which we have  the terms nephron, nephritis, etc.   Kidneys are a pair of excretory organs situated on the  posterior abdominal wall, one on each side of the  vertebral column, behind the peritoneum. They remove  waste products of metabolism and excess of water and  salts from the blood, and maintain its pH.   The kidneys occupy the epigastric, hypochondriac,  lumbar and umbilical regions (Fig. 24.1). Vertically they  extend from the upper border of twelfth thoracic  vertebra to the centre of the body of third lumbar  vertebra. The right kidney is slightly lower than the  left, and the left kidney is a little nearer to the median  plane than the right.   The transpyloric plane passes through the upper part  of the hilus of the right kidney, and through the lower  part of the hilus of the left kidney.   Each kidney is about 11 cm long, 6 cm broad, and 3 cm  thick. The left kidney is a little longer and narrower   than the right kidney. On an average the kidney weighs  150 g in males and 135 g in females. The kidneys are  reddish brown in colour.   The long axis of the kidney is directed downwards  and laterally, so that the upper poles are nearer to the  median plane than the lower poles (Fig. 24.2). The  transverse axis is directed laterally and backwards.   In the foetus the kidney is lobulated and is made up  of about 12 lobules. After birth the lobules gradually  fuse, so that in adults the kidney is uniformly smooth.  However, the evidence of foetal lobulation may persist.   Each kidney is bean-shaped. It has upper and lower  poles, medial and lateral borders, and anterior and  posterior surfaces.   The upper pole is broad and is in close contact with the  corresponding suprarenal gland. The lower pole is  pointed.   The anterior surface is said to be irregular and the  posterior surface flat, but it is often difficult to recognize  the anterior and posterior aspects of the kidney by  looking at the surfaces. The proper way to do this is to  examine the structures present in the hilum as described  below.   The lateral border is convex. The medial border is  concave. Its middle part shows a depression, the hilus  or hilum.   3 The renal pelvis, which is the expanded upper end  of the ureter.   Examination of these structures enables the anterior  and posterior aspects of the kidney to be distinguished  from each other. As the pelvis is continuous interiorly  with the ureter, the superior and inferior poles of the  kidney can also be distinguished by examining the hilum.  So it is possible to determine the side to which a kidney  belongs by examining the structures in the hilum.  Commonly, one of the branches of the renal artery enters  the hilus behind the renal pelvis, and a tributary of the  renal vein may be found in the same plane.   The kidneys are retroperitoneal organs and are only  partly covered by peritoneum anteriorly.   1 The upper pole of each kidney is related to the  corresponding suprarenal gland. The lower poles lie  about 2.5 cm above the iliac crests.   3 Posterior relations: The posterior surfaces of both  kidneys are related to the following.   In addition, the right kidney is related to twelfth rib,  and the left kidney to eleventh and twelfth ribs.   4 The structures related to the hilum have been  described earlier.   Out of these the hepatic and intestinal surfaces are  covered by peritoneum.   The lateral border of the right kidney is related to  the right lobe of the liver and to the hepatic flexure of  the colon (Fig. 24.3).    Fig. 24.5: Vertical section through the posterior abdominal wall  showing the relationship of the pleura to the kidney   Out of these the gastric, splenic and jejunal surfaces  are covered by peritoneum.   The lateral border of the left kidney is related to the  spleen and to the descending colon.   This is a thin membrane which closely invests the  kidney and lines the renal sinus. Normally it can be  easily stripped off from the kidney, but in certain  diseases it becomes adherent and cannot be stripped  (Figs 24.5 and 24.6).   This is a layer of adipose tissue lying outside the fibrous The fascia then extends anteromedially behind the  capsule. It is thickest at the borders of the kidney and kidney as bilaminated sheet, which divides at a variable  fills up the extra space in the renal sinus. point into thin layer which courses around the front of    Fig. 24.6: Transverse section through the lumbar region  showing the capsules of the kidney   The perirenal fascia was originally described as being  made up of two separate layers.   Posterior layer was called fascia of Zuckerkandall  and anterior layer as fascia of Gerota.   These two fasciae fused laterally to form lateral conal  fascia. According to this view, lateral conal fascia  continued anterolaterally behind colon to blend with  parietal peritoneum.   But lately it has been researched that the fascia is  not made up of fused fasciae, but of a single multi-  laminated structure which is fused posteromedially    kidney as anterior perirenal fascia and a thicker  posterior layer which continues anterolaterally as the  lateral conal fascia.   It was believed earlier that above the suprarenal  gland the anterior and posterior perirenal fasciae fuse  with each other and then get fused to the diaphragmatic  fascia, but research presently demonstrates that  superior aspect of perirenal space is "open" and is in  continuity to the bare area of liver on the right side and  with subphrenic extraperitoneal space on the left side.   On the right side at the level of upper pole of kidney,  anterior fascia blends with inferior coronary layer and  bare area of liver.   On the left side, anterior layer fuses with gastro¬  phrenic ligament.   Posterior layer on both right and left sides fuses with  fasciae of muscles of posterior abdominal wall, i.e. psoas  major and quadratus lumborum as well as with fascia  on the inferior aspect of thoracoabdominal diaphragm.   Medially the anterior layer is continuous from one  to the other kidney and the posterior layer is attached  either side of vertebra.   Below both the layer extend along the ureter and fuse  with iliac fascia.   It consists of a variable amount of fat lying outside the  renal fascia. It is more abundant posteriorly and  towards the lower pole of the kidney. It fills up the  paravertebral gutter and forms a cushion for the kidney.   Naked eye examination of a coronal section of the  kidney shows:    Fig. 24.7: A coronal section through the kidney showing the  naked eye structure including the blood supply of the kidney    The renal medulla is made up of about 10 conical  masses, called the renal pyramids . Their apices form  the renal papillae which indent the minor calyces.   a. Cortical arches or cortical lobules , which form caps  over the bases of the pyramids.   Each pyramid along with the overlying cortical arch  forms a lobe of the kidney.   The renal sinus is a space that extends into the kidney  from the hilus. It contains:   c. The renal pelvis. The pelvis divides into 2 to 3  major calyces, and these in their turn divide into  7 to 13 minor calyces. Each minor calyx (kalyx -  cup of a flower) ends in an expansion which is  indented by one to three renal papillae.   Each kidney is composed of one to three million  uriniferous tubules. Each tubule consists of two parts  which are embryologically distinct from each other.  These are as follows.   The excretory part, called the nephron , which  elaborates urine. Nephron is the functional unit of the  kidney, and comprises:   a. Renal corpuscle or Malpighian corpuscle, (for  filtration of substances from the plasma) made up  of glomerulus (Latin ball) a tuft of capillaries and  Bowman's capsule (Fig. 24.8).   b. Renal tubule, (for selective resorption of substances  from the glomerular filtrate) made up of the  proximal convoluted tubule, loop of Henle with  its descending and ascending limbs, and the distal  convoluted tubule (Fig. 24.8).   The collecting part begins as a junctional tubule from  the distal convoluted tubule. Many tubules unite  together to form the ducts of Bellini which open into  the minor calyces through the renal papillae.   Juxtaglomerular apparatus is formed at the vascular  pole of glomerulus which is intimately related to its  own ascending limb of the Henle's loop near the distal  convoluted tubule. The apparatus consists of:   b. Juxtaglomerular cells, formed by the epithelioid  cells in the media of the afferent arteriole.   c. Some agranular cells between macula densa and  the glomerulus proper.   The renal artery gives 5 segmental branches, 4 from its  anterior division and one from its posterior division  (Fig. 24.9)    Junctional tubule  Distal convoluted tubule  Afferent arteriole  Efferent arteriole  Glomerulus  Bowman's capsule  Proximal    Fig. 24.8: Placement of the uriniferous tubule/nephron in various  zones of kidney    Fig. 24.9: Vascular segments of the kidney as seen in a sagittal  section. Big anterior branch supplies four segments and posterior  branch supplies only one segment    The segments are apical, upper, middle and lower  on anterior aspect. On posterior aspect segments seen  are posterior and parts of apical and lower segments.   The blood supply of kidney shown in Flow chart 24.1  and Figs 24.7 and 24.10.   The lymphatics of the kidney drain into the lateral aortic  nodes located at the level of origin of the renal arteries  (L2).   The kidney is supplied by the renal plexus, an off shoot  of the coeliac plexus. It contains sympathetic (T10-L1)    fibres which are chiefly vasomotor. The afferent nerves  of the kidney belong to segments T10 to T12.   In exposing the kidney from behind, the following  layers have to be reflected one by one (Fig. 24.11).   3 Posterior layer of thoracolumbar fascia with  latissimus dorsi and serratus posterior inferior   7 Anterior layer of thoracolumbar fascia in which the  related nerves are embedded.   Middle layer of thoracolumbar fascia (5)  Posterior layer of thoracolumbar fascia (3)    Fig. 24.11: Transverse section through the upper lumbar region showing the layers of thoracolumbar fascia encountered during  exposure of the kidney from behind    Figs 24.12a and b: Histology of the kidney: (a) Cortex, and (b) medulla   The cortex of kidney shows cut sections of glomeruli,  many sections of proximal convoluted tubule, some  sections of distal convoluted tubule and few collecting  ducts.   Section through the pyramid of the medulla shows  light staining collecting ducts, sections of loop of  Henle, thick and thin segments of descending and  ascending limbs, capillaries and connective tissue (Figs  24.12a and b).    • In surgical exposures of the kidney, when  sometimes the 12th rib is resected for easier  delivery of the kidney, danger of opening the pleural    cavity must be borne in mind. The lower border  of the pleura lies in front of the 12th rib and behind  the diaphragm. The order of structures from  anterior to posterior side being diaphragm, pleura  and rib. When the 12th rib is absent or is too short  to be felt, the 11th rib may be mistaken for the  12th, and the chances of opening the pleural cavity  are greatly increased (Fig. 24.13). Lithotripsy has  replaced conventional method to some degree.   • The angle between the lower border of the 12th  rib and the outer border of the erector spinae is  known as the renal angle. It overlies the lower part  of the kidney. Tenderness in the kidney is elicited  by applying pressure over this angle, with the  thumb (Fig. 24.14).   • Blood from a ruptured kidney or pus in a  perinephric abscess first distends the renal fascia,  then forces its way within the renal fascia  downwards into the pelvis. It cannot cross to  opposite side because of the fascial septum and  midline attachment of the renal fascia.   • Kidney is palpated bimanually, with one hand  placed in front and the other hand behind  the flank. When enlarged, the lower pole of kidney  becomes palpable on deep inspiration (Fig. 24.15).   • A floating kidney can move up and down within  the renal fascia, but not from side to side.   • In such condition the posterior layer of renal fascia  can be sutured with diaphragm and kidney can  be fixed in position.   • The common diseases of kidney are nephritis,  pyelonephritis, tuberculosis of kidney, renal  stones and tumours.   Common manifestations of a kidney disease are  renal oedema and hypertension. Raised blood  urea indicates suppressed kidney function and  renal failure. Kidney transplantation can be done  in selected cases (Figs 24.16a and b).    • One common congenital condition of kidney is  polycystic kidney which leads to hypertension  (Fig. 24.17).   • In cases of chronic renal failure dialysis needs to  be done. It can be done as peritoneal dialysis  (Fig. 24.18) or haemodialysis (Fig. 24.19).   • The kidneys are likely to be injured due to  penetrating injuries to lower thoracic cage. These  may also be injured by kicks in the renal angle—  angle between the vertebral column and 12th rib.   • Kidney is likely to have stones as urine gets  concentrated here (Fig. 24.20a).   • Kidneys stone lies on the body of vertebra  (Fig. 24.20b). Gallstones lie anterior to body of  vertebra (Fig. 24.20c).    The ureters are a pair of narrow, thick-walled muscular  tubes which convey urine from the kidneys to the  urinary bladder (Fig. 24.21).    Fig. 24.13: Relation of twelfth rib to pleural cavity, diaphragm  and kidney   Figs 24.16a and b: (a) Donor’s left kidney transplanted, and  (b) recipient’s right kidney   Figs 24.20a to c: (a) Staghorn renal stone, (b) renal stone on  the body of vertebra, and (c) gallstone anterior to the vertebra    They lie deep to the peritoneum, closely applied to  the posterior abdominal wall in the upper part, and to  the lateral pelvic wall in the lower part.    Each ureter is about 25 cm (10 inches) long, of which the Fig. 24.21: The location of the ureters on the posterior   upper half (5 inches) lies in the abdomen, and the lower abdominal and lateral pelvic walls   half (5 inches) in the pelvis. It measures about 3 mm in  diametre, but it is slightly constricted at five places.   The ureter begins within the renal sinus as a funnel-  shaped dilatation, called the renal pelvis. The pelvis  issues from the hilus of the kidney, descends along its  medial margin, or partly behind it. Gradually it narrows  till the lower end of the kidney where it becomes the  ureter proper.   The ureter passes downwards and slightly medially  on the tips of transverse processes and the psoas major  muscle, and enters the pelvis by crossing in front of the  termination of the common iliac artery (Fig. 24.22).   In the lesser or true pelvis the ureter at first runs  downwards, and slightly backwards and laterally,  following the anterior margin of the greater sciatic notch.  Opposite the ischial spine it turns forwards and medially  to reach the base of the urinary bladder.   3 Point of crossing of ureter by ductus deferens or  broad ligament of uterus.   In the renal sinus, branches of renal vessels lie both in  front and behind it (Fig. 24.7).   On the right side , there are the renal vessels and the  second part of the duodenum. On the left side , there are  the renal vessels, the pancreas, the peritoneum and the  jejunum (Fig. 24.3).   On the left side (Fig. 24.25) the ureter is related to:    Fig. 24.24: Anterior relations of the abdominal part of the right  ureter    Fig. 24.26: Relations of the ureter to the transverse processes  of lumbar vertebrae and the ischial spine    Fig. 24.25: Anterior relations of the abdominal part of the left  ureter   8 In the female, it forms the posterior boundary of the  ovarian fossa.   1 Ductus deferens crosses the ureter superiorly from  lateral to medial side.   2 Seminal vesicle lies below and behind the ureter  (Fig. 24.28).   On the right side there is the inferior vena cava; on the  left side , there is the left gonadal vein, and still further  medially, the inferior mesenteric vein.   2 Commencement of the anterior trunk of the internal  iliac artery   1 The ureter lies in the extraperitoneal connective  tissue in the lower and medial part of the broad  ligament of the uterus (Fig. 24.29).   2 Uterine artery lies first above and in front of the ureter  for a distance of about 2.5 cm and then crosses it  superiorly from lateral to medial side.   3 The ureter lies about 2 cm lateral to the supravaginal  portion of the cervix. It runs slightly above the lateral  fornix of the vagina.   4 The terminal portion of the ureter lies anterior to the  vagina.    The intravesical oblique course of the ureter has a  valvular action, and prevents regurgitation of urine   Fig. 24.28: Posterior view of the male urinary bladder showing  the relations of the ureter to the vas deferens and the seminal  vesicle   from the bladder to the ureter. The ureteric openings  lie about 5 cm apart in a distended bladder, and only  2.5 cm apart in an empty bladder.   1 The upper part receives branches from the renal  artery. It may also receive branches from the gonadal,  or colic vessels.   2 The middle part receives branches from the aorta. It  may also receive branches from the gonadal, or iliac  vessels.   3 The pelvic part is supplied by branches from the  vesical, middle rectal, or uterine vessels. The arteries    Fig. 24.29: Anterior view of the uterus and vagina showing the  relation of the ureter to the uterine artery, the cervix of the uterus,  and the vagina    to the ureter lie closely attached to peritoneum. They  divide into ascending and descending branches  which first form a plexus on the surface of the ureter,  and then supply it.   The upper and middle parts receive branches from  medial side, while the pelvic part gets its arterial supply  from lateral side.   The ureter is supplied by sympathetic from T10-L1  segments and parasympathetic from S2-S4 nerves.  They reach the ureter through the renal, aortic and  hypogastric plexuses. All the nerves appear to be  sensory in function.   The epithelial lining is of transitional epithelium.  Muscle coat in upper two-thirds has inner longi¬  tudinal and outer circular fibres. Lower one-third  comprises an additional outer longitudinal layer.  Connective tissue forms the outer layer (Fig. 24.30).   • Inner longitudinal and outer circular layer  of smooth muscle fibres   Kidney develops from metanephros, though pro¬  nephros and mesonephros appear to disappear. Only  the duct of mesonephros, the mesonephric duct persists.   Thus the nephrons of the kidney arise from the  metanephros. Parts of nephron formed are Bowman's  capsule, proximal convoluted tubule, loop of Henle,  distal convoluted tubule. Tuft of capillaries form the  glomeruli.   Collecting part of kidney develops from ureteric bud,  which is an outgrowth of the mesonephric duct.  Ureteric bud gets capped by the metanephric tissue,  the ureteric bud forms ureter. Soon it dilates to form  renal pelvis and divides and subdivides to form major  and minor calyces and 1-3 million collecting tubules.   1 Nonunion of the excretory and collecting parts of  the kidney results in the formation of congenital  polycystic kidney.   2 Fusion of the lower poles may occur, resulting in a  horseshoe kidney. In these cases the ureters pass  anterior to the isthmus of the kidney.   3 The early pelvic position of the kidney may persist. The  renal artery then arises from the common iliac artery.   4 Unilateral aplasia or hypoplasia of the kidney may  occur. Sometimes both kidneys may lie on any one  side of the body.   5 The ureteric bud may divide into two, forming  double ureter partly or completely.    • Ureteric colic: This term is used for severe pain due  to a ureteric stone or calculus which causes spasm  of the ureter. The pain starts in the loin and  radiates down the groin, the scrotum or the labium  majus and the inner side of the thigh. Note that  the pain is referred to the cutaneous areas  innervated by segments, mainly Til to L2, which  also supply the ureter (Fig. 24.33).   • Ureteric stone: A ureteric stone is liable to become  impacted at one of the sites of normal constriction  of the ureter, e.g. pelviureteric junction, brim of  the pelvis and intravesical course (Fig. 24.23).   • Duplex ureter: 2 ureters drain renal pelvis on one  side called as duplex system.   • Ectopic ureter: Single ureter and longer ureter insert  more caudally and medially than normal one.   • Blood supply: Upper and middle parts of ureter are  supplied by branches from its medial side. Pelvic  part is supplied by branches from its lateral side.   A common surgical error could be to ligate and cut  ureter with uterine artery while removing uterus.   V - Renal vein  A - Renal artery  U - Pelvis of ureter    Figs 24.31a to e: Development of excretory system of permanent kidney: (a) Metanephric cap, (b) renal vesicles, (c) s-shaped  tubule, (d) Bowman s capsule and glomerulus, and (e) differentiation and growth of parts of nephron, loop of Henle, proximal and  distal convoluted tubules    Figs 24.32a to e: Development of collecting system of permanent kidney: (a) Formation of ureteric buds, (b) capping of ureteric  bud by metanephros, and (c to e) formation of ureter, renal pelvis, major calyces, minor calyces and collecting tubules    * Order of structures at the hilum of kidney is renal  vein, renal artery and pelvis of ureter from before  backwards.   * Kidney is kept in position by intra-abdominal  pressure, pararenal, fat, renal fascia, perirenal fat,  renal capsule.   * There are 5 renal segments. These are apical, upper,  middle, lower and posterior.    * Ureter shows 5 constrictions. These are at pelviure-  teric junction, at the brim of pelvis, at crossing with  ductus deferens or broad ligament, intravesical  course and at its termination at the trigone of the  urinary bladder.   * Most of the renal stones are radiopaque while most  of the gallstones non-radiopaque.   * Excretory part of kidney-develops from meta-  nephros; collecting part of kidney develops from  ureteric bud, arising from mesonephric duct.   • How will the new ureter and blood vessels be  connected?   Ans: The new kidney is put in the right or left iliac  fossa. The diseased kidney cut off from blood vessels  and ureter is left within the patient's body   The new ureter is connected to the urinary  bladder. The renal blood vessels are connected to  internal iliac vessels. With proper precautions and  medications, life gets sustained.    1. All of the following are related to the anterior  surface of left kidney except :   a. Latissimus dorsi b. Transversus abdominis  c. Psoas major d. Quadratus lumborum   1, c 2. a 3. d 4. b 5. c 6. a 7. b 8. c   The suprarenal or adrenal glands are endocrine glands  which help to maintain water and electrolyte balance.  These also prepare the body for any emergency. These  are subjected to hyper- or hypofunctioning. Lack of  secretion of the cortical part leads to Addison's disease.  Excessive secretion causes retention of salts and fluids.   Locate the suprarenal glands situated along the upper  pole and medial border of the two kidneys. Identify the  structures related to the right and left suprarenal glands.   The suprarenal glands are a pair of important endocrine  glands situated on the posterior abdominal wall over  the upper pole of the kidneys behind the peritoneum  (Fig. 25.1). They are made up of two parts.    1 An outer cortex of mesodermal origin, which secretes  a number of steroid hormones.   2 An inner medulla of neural crest origin, which is  made up of chromaffin cells and secretes adrenaline  and noradrenalin or catecholamines.   Each gland lies in the epigastrium, at the upper pole of  the kidney, in front of the crus of the diaphragm,  opposite the vertebral end of the 11th intercostal space  and the 12th rib.   Each gland measures 50 mm in height, 30 mm in  breadth and 10 mm in thickness. It is approximately  one-third of the size of kidney at birth and about one-  thirtieth of it in adults. It weighs about 5 g, the medulla  forming one-tenth of the gland. Right suprarenal is  triangular or pyramidal in shape and the left is  semilunar in shape.   The suprarenal glands are immediately surrounded by  areolar tissue containing considerable amount of fat.   Outside the fatty sheath, there is the perirenal fascia.  Between the two layers lies the suprarenal gland  (Fig. 25.2). The two layers are not fused above the  suprarenal. The perirenal space is open and is in  continuity with bare area of liver on the right side and  with subphrenic extraperitoneal space on the left side.  The gland is separated from the kidney by a septum.   The right suprarenal gland is triangular to pyramidal  in shape. It has:   Fig. 25.2: The kidney and suprarenal glands enclosed in the  renal fascia with a septum intervening   Comparison of right and left suprarenal glands is  given in Table 25.1.   Naked eye examination of a cross-section of the  suprarenal gland shows an outer part, called the cortex ,  which forms the main mass of the gland, and a thin  inner part, called the medulla , which forms only about  one-tenth of the gland. The two parts are absolutely  distinct from each other structurally, functionally and  developmentally.    Figs 25.3a to d: Relations of the suprarenal glands: (a) Anterior view of right suprarenal gland, (b) anterior view of left suprarenal  gland, (c) posterior view of left suprarenal gland, and (d) posterior view of right suprarenal gland   Apex: Bare area of liver  Base: Upper pole of right kidney   Inferior vena cava, bare area of liver  Right crus of diaphragm, right kidney  Presents hilum, right vein emerges  Coeliac ganglion  Liver   a. The outer, zona glomerulosa which produces  mineralocorticoids that affect electrolyte and  water balance of the body.   The medulla is composed of chromaffin cells that  secrete adrenaline and noradrenalin. It contains cells  in groups with lots of capillaries. Autonomic ganglion  cells are also seen.   1 The superior suprarenal artery, a branch of the inferior  phrenic artery.   2 The middle suprarenal artery, a branch of the  abdominal aorta.   3 The inferior suprarenal artery, a branch of the renal  artery (Fig. 25.4).   Lymphatics from the suprarenal glands drain into the  lateral aortic nodes.   The suprarenal medulla has a rich nerve supply  through myelinated preganglionic sympathetic fibres.  The chromaffin cells in it are considered homologous  with postganglionic sympathetic neurons.    Each gland is drained by one vein (Fig. 25.5). The right  suprarenal vein drains into the inferior vena cava, and  the left suprarenal vein into the left renal vein.   These are small masses of cortical tissue often found in  the areolar tissue around the main glands and  sometimes in the spermatic cord, the epididymis, and  the broad ligament of the uterus.   Cortex: It consists of three zones. Outer zone is zona  glomerulosa which contains groups of columnar cells  with spherical nuclei. Middle zone or zona fasciculata  has cells arranged in vertical rows. Cells have lots of  vacuoles in the cytoplasm. The inner zone or zona  reticularis contains cells in an anastomosing network.  These cells are less vacuolated.   Medulla: It is composed of chromaffin cells, arranged  in small groups, surrounded by capillaries. In between  these cells are autonomic ganglion cells (Fig. 25.6).    • Outer covering is the cortex and inside is the medulla   • Cortex comprises zona glomerulosa (outermost zone fasciculata  (middle zone), and zona reticularis (innermost zone)    an inverted horseshoe, or an H-shaped body. They  develop during foetal life, attain their maximum size  in the first three years of life, and gradually atrophy to  disappear by the age of 14 years. The chromaffin cells  of the para-aortic bodies secrete noradrenaline.   Other small chromaffin bodies are found in the foetus  in all parts of the prevertebral sympathetic plexuses of  the abdomen and pelvis. They reach their maximum  size between the 5th and 8th months of foetal life. In  adults, they can be made out only in the vicinity of the  coeliac and superior mesenteric arteries.   Also known as glomus coccygeum, it is a small oval  body about 2.5 cm in diameter situated in front of the  coccyx. It is closely connected to the termination of  the median sacral artery and to the ganglion impar. It is  made up of epithelioid cells grouped around a  sinusoidal capillary. Thus it does not clearly belong to  the chromaffin system.    The cortex of the gland develops from mesoderm of  coelomic epithelium while the medulla is derived from  the neural crest cells (neuroectoderm).    Chromaffin system is made up of cells which have an  affinity for certain salt of chromic acid. Such cells are  called chromaffin cells or pheochromocytes. These are  situated close to sympathetic ganglia because both of  them develop from the cells of the neural crest.  Chromaffin cells secrete adrenaline and noradrenaline.  This system includes the following groups of cells.   5 Small masses of chromaffin cells scattered irregularly  amongst ganglia of sympathetic chain, splanchnic  nerves, autonomic plexuses, and may be closely  related to various organs like heart, liver, kidney,  ureter, prostate, epididymis, etc.   These are rounded nodules of chromaffin tissue, about  2 mm in diameter, situated inside or closely related to  the ganglia of the sympathetic chain. In adults they are  generally represented by microscopic remnants only.   Two para-aortic bodies, each about 1 cm long, lie on  each side of the origin of the inferior mesenteric artery.  They are connected together above the artery to form    * Suprarenal gland can be demonstrated radiologically  by computerised tomography (CT scan).   * Insufficiency of cortical secretion due to atrophy  or tuberculosis of the cortex results in Addison's  disease . It is characterized by muscular weakness,  low blood pressure, anaemia, pigmentation of skin  and terminal circulatory and renal failure.   * Excessive cortical secretion due to hyperplasia of  the cortex may produce various effects:   a. In adults, hyperglucocorticism causes Cushing's  syndrome , which is characterized by obesity,  hirsutism, diabetes and hypogonadism.   c. In men, excessive oestrogens may cause  feminization and breast enlargement.   d. In children, excessive sex hormones cause  adrenogenital syndrome , cortical hyperplasia. In  female foetus excessive androgens cause female  pseudohermaphroditism ; in the male foetus, it  causes excessive development of external  genital organs.   * Bilateral removal of adrenal glands (adrenalectomy)  is done as a treatment of some advanced and  inoperable cases of disseminated carcinoma of the  breast and prostate which do not respond to  radiotherapy and which are considered to be  dependent on hormonal control.   * Benign tumours of the suprarenal medulla  (pheochromocytoma) cause attacks of hypertension  associated with palpitation, headache, excessive  sweating and pallor of skin.    • Suprarenal gland sustains the body during stress  by its cortical and medullary hormones.   • Suprarenal is drained by one vein which ends in  inferior vena cava on the right side and in left renal  vein on the left side.    A patient has bouts of severe high blood pressure  with headache and palpitation. The diagnosis is  pheochromocytoma.   • Where does the blood supply to suprarenal gland  come from?   Ans: The diagnosis is done by history, biochemical  tests and CT scans.   There are three arteries supplying blood to the  gland. These are superior suprarenal from inferior  phrenic; middle suprarenal from abdominal aorta  and inferior suprarenal from the renal artery.   Vein of suprarenal is only one. On the right side,  the vein drains into inferior vena cava.   On the left side the suprarenal vein drains into  the left suprarenal vein.   a. Right renal vein b. Inferior vena cava  c. Left renal vein d. Lumbar vein   The diaphragm is the chief muscle of quiet respiration.  Though it separates the thoracic and abdominal cavities,  it gives passage to a number of structures passing in  both the directions. Since it develops in the region of  the neck, it continues to be innervated by the same loyal  nerve despite its descent to a much lower level.   During inspiration, the central tendon is pulled by  the contracting muscle fibres, so that inferior vena caval  opening is enlarged helping in venous return to the  heart. This venous blood is pumped to the lungs. The  air also gets into the lungs during inspiration. So both  the venous blood in the capillaries and air in the alveoli  come close by in the lung tissue, separated by the lining  of the alveoli. The exchange of gases takes place, carbon  dioxide is expelled in expiration and purified blood is  returned to the left atrium.   Strip the peritoneum from the under aspect of the  diaphragm and expose its crura on the anterior surfaces  of the upper 2 or 3 lumbar vertebrae. Find the arcuate  ligaments.   Expose the slips of diaphragm arising from the  internal surfaces of the remaining costal cartilages and  identify the intercostal vessels and nerves entering the  abdominal wall between them.   Locate the main openings in the diaphragm and  identify the structures passing through each one of  them. Explore the other minor openings and the  structures traversing these.   The diaphragm is a dome-shaped muscle forming the  partition between the thoracic and abdominal cavities.  It is the chief muscle of respiration.   Muscle fibres form the periphery of the partition.  They arise from circumference of the thoracic outlet and  are inserted into a central tendon (Fig. 26.1).   The muscle fibres may be grouped into three parts,  sternal, costal and lumbar.   The sternal part arises by two fleshy slips from the  back of the xiphoid process.   The costal part arises from the inner surfaces of the  cartilages and the adjacent parts of the lower six ribs  on each side, interdigitating with the transversus  abdominis.   The lumbar part arises from the medial and lateral  lumbocostal arches and from the lumbar vertebrae by  right and left crura .   a. The medial lumbocostal arch or medial arcuate  ligament is a tendinous arch in the fascia covering  the upper part of the psoas major. Medially, it is  attached to the side of the body of vertebra LI and  is continuous with the lateral margin of the  corresponding crus. Laterally, it is attached to the  front of the transverse process of vertebra LI.   b. The lateral lumbocostal arch or lateral arcuate  ligament is a tendinous arch in the fascia covering  the upper part of the quadratus lumborum. It is  attached medially to the front of the transverse  process of vertebra LI, and laterally to the lower  border of the 12th rib.   c. The right crus is larger and stronger than the left  crus, because it has to pull down the liver during   Median arcuate ligament  Medial arcuate ligament  Lateral arcuate ligament  Subcostal vessels and nerve  Left crus of diaphragm  Sympathetic trunk    each inspiration. It arises from the anterolateral  surfaces of the bodies of the upper three lumbar  vertebrae and the intervening intervertebral discs,  d. The left crus arises from the corresponding parts  of the upper two lumbar vertebrae. The medial  margins of the two crura form a tendinous arc  across the front of the aorta, called the median  arcuate ligament.   1 From the circumferential origin described above, the  fibres arch upwards and inwards to form the right  and left domes. The right dome is higher than the  left dome (Fig. 26.2a). In full expiration, it reaches  the level of the fourth intercostal space. The left dome  reaches the fifth rib. The central tendon lies at the  level of the lower end of the sternum at 6th costal  cartilage. The downward concavity of the dome is    occupied by the liver on the right side and by the  fundus of the stomach on the left side.   2 The medial fibres of the right crus run upwards and  to the left, and encircle the oesophagus.   3 In general, all fibres converge towards the central  tendon for their insertion (Fig. 26.2b).   The central tendon of the diaphragm lies below the  pericardium and is fused to the latter. The tendon is  trilobar in shape, made up of three leaflets. The middle  leaflet is triangular in shape with its apex directed  towards the xiphoid process. The right and left leaflets  are tongue-shaped and curve laterally and backwards,  the left being a little narrower than the right. The central  area consists of four well-marked diagonal bands which  fan out from a central point of decussation located in  front of the opening for the oesophagus (Fig. 26.1).    Figs 26.2a to c: Shape of the diaphragm: (a) Anteroposterior view shows the right and left domes, and (b) in superior view, it is  kidney-shaped   The aortic opening is osseoaponeurotic. It lies at lower  border of the 12th thoracic vertebra. It transmits:   The oesophageal opening lies in the muscular part of  the diaphragm, at the level of the 10th thoracic vertebra.  It transmits:   c. Oesophageal branches of the left gastric artery,  with some oesophageal veins that accompany the  arteries.   The vena caval opening lies in the central tendon of  the diaphragm at the level of the 8th thoracic vertebra.  It transmits:   1 Each crus of the diaphragm is pierced by the greater  and lesser splanchnic nerves. The left crus is pierced  in addition by the hemiazygos vein.    2 The sympathetic chain passes from the thorax to the  abdomen behind the medial arcuate ligament or  medial lumbocostal arch.   3 The subcostal nerve and vessels pass behind the  lateral arcuate ligament or lateral lumbocostal arch  (Fig. 26.1).   4 The superior epigastric vessels and some lymphatics  pass between the origins of the diaphragm from the  xiphoid process and the 7th costal cartilage. This gap  is known as Larry's space or foramen of Morgagni.   5 The musculophrenic vessels pierce the diaphragm  at the level of 9th costal cartilage.   The phrenic nerves are the sole motor nerves to the  diaphragm (ventral rami C3, C4, C5).   The phrenic nerves are sensory to the central part, and  the lower six thoracic nerves are sensory to the  peripheral part of the diaphragm.   In addition to the diaphragm, the phrenic nerves also  supply sensory fibres to the mediastinal and  diaphragmatic pleurae, the fibrous pericardium, the  parietal layer of serous pericardium, and the part of  the parietal peritoneum lying below the central part of  the diaphragm. Through its communications with the  phrenic branches of the coeliac plexus, the phrenic    nerve is also distributed to the falciform and coronary  ligaments of the liver, the inferior vena cava, the  suprarenal glands, and the gallbladder.   1 The diaphragm is the principal muscle of inspiration .  On contraction, the diaphragm descends increasing  the vertical diameter of the thorax. The excursion of  the diaphragm is about 1.5 cm during quiet breathing.  In deep inspiration, it may be from 6 to 10 cm.   2 The diaphragm acts in all expulsive acts to give  additional power to each effort. Thus before  sneezing, coughing, laughing, crying, vomiting,  micturition, defaecation, or parturition, a deep  inspiration takes place. This is followed by closure  of the glottis and powerful contraction of the trunk  muscles.   3 The sphincteric action in lower end of oesophagus  is due to the contraction of the intrinsic muscle in  the lower 2 cm of the oesophagus.   The position of the diaphragm in the thorax depends  upon three main factors. These are as follows.   a. The elastic recoil of lung tissue tends to pull the  diaphragm upwards.   b. On lying down, the pressure exerted by the  abdominal viscera pushes the diaphragm  upwards. On standing or sitting, the viscera tend  to pull the diaphragm downwards.   c. While standing, the muscles in the abdominal wall  contract, increasing the intra-abdominal pressure.  This pressure tends to push the diaphragm  upwards. In sitting or lying down, the muscles  are relaxed (see Chapter 13, Volume 1).   Because of these factors the level of the diaphragm  is highest in the supine position, lowest while sitting,  and intermediate while standing. The higher is the  position of the diaphragm, the greater respiratory  excursion.   3 Lateral thoracic wall contributes to the circum¬  ferential portion of the diaphragm.    • Hiccough or hiccup is the result of spasmodic  contraction of the diaphragm. It may be:   a. Peripheral, due to local irritation of the dia¬  phragm or its nerve.    b. Central, due to irritation of the hiccough centre  in the medulla. Uraemia is an important cause  of hiccough.   Shoulder tip pain: Irritation of the diaphragm may  cause referred pain in the shoulder because the  phrenic and supraclavicular nerves have the same  root values (C3, C4, C5) (see Figs 22.9 and 23.9).  Unilateral paralysis of the diaphragm , due to a lesion  of the phrenic nerve anywhere in its long course,  is a common occurrence. The paralysed side  moves opposite to the normal side, i.e. paradoxical  movements. This can be seen both clinically and  fluoroscopically.   Eventration is a condition in which diaphragm is  pushed upwards due to a congenital defect in the  musculature of its left half which is represented  only by a fibrous membrane containing a few  scattered muscle fibres.   a. Retrosternal hernia: It occurs through the space  between the xiphoid and costal origins of the  diaphragm, or foramen of Morgagni/ or space  of Larrey. It is more common on the right  side and lies between the pericardium and the  right pleura. Usually it causes no symptoms  (Fig. 26.4).   b. Posterolateral hernia: This is by far the commonest  type of congenital diaphragmatic hernia. It  occurs through the pleuro-peritoneal hiatus or  foramen ofBochdalek situated at the periphery of  the diaphragm in the region of attachments to  the 10th and 11th ribs. It is more common on  the left side. There is a free communication  between the pleural and peritoneal cavities.  Such a hernia may cause death of the infant  within a few hours of birth due to acute  respiratory distress caused by abdominal  viscera filling the left chest. This hernia requires  operation in the first few hours of life.   c. Posterior hernia: This is due to failure of  development of the posterior part of the  diaphragm. One or both crus may be absent.  The aorta and oesophagus lie in the gap, but  there is no hernial sac.   d. Central hernia: It is rare, left-sided, and is  supposed to be the result of rupture of the foetal  membranous diaphragm in the region of the  left dome.   a. Traumatic hernia: It is due to bullet injuries of  the diaphragm.   - A congenital hiatal hernia is due to persistence  of an embryonic peritoneal process in the  posterior mediastinum in front of the cardiac  end of the stomach. The stomach can 'roll'  upwards until it lies upside down in the  posterior mediastinum. It is, therefore, called  a rolling type of hernia. It is a rare type of  hernia where the normal relationship of the  cardio-oesophageal junction to the  diaphragm is undisturbed, and, therefore, the  mechanics of the cardio-oesophageal junction  usually remains unaltered (Fig. 26.5a).   - An acquired hiatal hernia or sliding type  (Fig. 26.5b) is the commonest of all internal  hernia. It is due to weakness of the phrenico-  oesophageal membrane which is formed by  the reflection of diaphragmatic fascia to the  lower end of the oesophagus. It is often  caused by obesity, or by operation in this area.  The cardiac end can slide up through the  hiatus. In this way the valvular mechanism  at the cardio-oesophageal junction is  disturbed causing reflux of gastric contents  into the oesophagus.   Figs 26.5a and b: Types of hiatal hernia: (a) Congenital  rolling, and (b) acquired sliding    * The sole motor nerve supply of the diaphragm is  phrenic nerve (C4). It develops in the neck, but is  carried downwards due to developmental factors.   * Inferior vena caval opening is in the central tendon.  During inspiration the opening gets dilated  allowing increased venous return.   • Right crus of diaphragm acts as a sphincter at the  gastro-oesophageal junction.   • Hiatal hernia may be of rolling or sliding type. The  rolling type is usually congenital while the sliding  type is usually acquired.    A busy obese businessman complains of acidity. He  has been diagnosed as having sliding diaphragmatic  hernia   • What is the relation of cardiac end of stomach to  cardio-oesophageal junction?   Ans: This type of hernia occurs in busy executives or  businessmen. It occurs due to weakness of phrenico-  oesophageal membrane, which is formed by the  reflection of diaphragmatic fascia to the lower end of  oesophagus. The cardiac end may slide up through  the hiatus. In this way the valvular mechanism at the  cardio-oesophageal junction is disturbed, causing  reflux of gastric contents up to the oesophagus.    1. Which of the following structures does not pass  through the diaphragm?   2. Which of the following structures does not pass  through oesophageal hiatus?   3. Which of the following apertures lies in the central  tendon of diaphragm?    4. Which of the following structures form proper  sphincter at the lower end of oesophagus?   6 Nerves of the posterior abdominal wall including  lumbar plexus and the abdominal part of autonomic  nervous system.   Expose the centrally placed abdominal aorta and inferior  vena cava to the right of aorta. Trace the ventral, lateral,  posterior and terminal branches of abdominal aorta and  the respective tributaries of inferior vena cava. Remove  the big lymph nodes present in the posterior abdominal  wall.   Identify the muscles of the posterior abdominal wall  by removing their fascial coverings. These are psoas  major, quadratus lumborum, and iliacus. Avoid injury to  the vessels and nerves related to the muscles.   Detach psoas major from the intervertebral discs and  vertebral bodies and trace the lumbar vessels and the  rami communicans posteriorly deep to the tendinous  arches from which psoas major arises. Dissect the  genitofemoral nerve seen on the anterior surface of  psoas major.   Trace the various branches of lumbar plexus, e.g.  iliohypogastric, ilioinguinal, lateral cutaneous nerve of  thigh and femoral nerve. These exit from the lateral    border of psoas major. Identify obturator and lumbosacral  trunk seen on the medial aspect of the muscle.   Locate the lumbar part of the right and left sympathetic  chains. Trace their branches into the coeliac and superior  mesenteric plexuses of nerves in addition to giving rami  communicans to the lumbar spinal nerves.   The abdominal aorta begins in the midline at the aortic  opening of the diaphragm, opposite the lower border  of vertebra T12. It runs downwards and slightly to the  left in front of the lumbar vertebrae, and ends in front  of the lower part of the body of vertebra L4, about  1.25 cm to the left of the median plane, by dividing into  the right and left common iliac arteries (Fig. 27.1). Due  to the forward convexity of the lumbar vertebral  column, aortic pulsations can be felt in the region of  the umbilicus, particularly in slim persons.   2 Body of the pancreas, with the splenic vein  embedded in its posterior surface (see Fig. 23.15).   1 The bodies of upper four lumbar vertebrae and the  corresponding intervertebral discs (see Fig. 21.1).   3 Cisterna chyli and the azygos vein in the upper part.    Inferior vena cava  Hepatic veins  Right inferior phrenic vein  Right suprarenal vein  Middle suprarenal artery  Coeliac trunk  Superior mesenteric artery  Right renal vessels   Left inferior phrenic artery  Superior suprarenal artery  Pre-aortic lymph nodes  Left inferior phrenic vein  Left suprarenal vein  Left inferior suprarenal artery  Left renal artery  Left renal vein  Left gonadal vein  Inferior mesenteric artery   Fig. 27.1: The abdominal aorta, inferior vena cava and associated lymph nodes    To the left side of the aorta there are from above  downwards:   The branches of the abdominal aorta are classified as  given below (Fig. 27.1).   Ventral branches , which develop from ventral  splanchnic or vitelline arteries and supply the gut. These  are as follows.   a. Coeliac trunk (see Chapter 21) gives left gastric,  common hepatic and splenic branches.   b. Superior mesenteric artery ( see Chapter 21) gives  inferior pancreaticoduodenal, middle colic, right  colic, ileocolic and 12-15 jejunal and ileal branches.   c. Inferior mesenteric artery (see Chapter 21) gives  left colic, sigmoid arteries and continues as  superior rectal.   Lateral branches , which develop from the lateral  splanchnic or mesonephric arteries and supply the  viscera derived from the intermediate mesoderm. These  are right and left:   Dorsal branches represent the somatic intersegmental  arteries and are distributed to the body wall. These are:   Terminal branches are a pair of common iliac arteries.  They supply the pelvis and lower limbs.   Inferior phrenic arteries arise from the aorta just above  the coeliac trunk. Each artery runs upwards and  laterally on the corresponding crus of the diaphragm,  medial to the suprarenal gland. Each artery gives off  two to three superior suprarenal arteries, and is then  distributed to the diaphragm.   Middle suprarenal arteries arise at the level of the  superior mesenteric artery. Each passes laterally and  slightly upwards over the corresponding crus of the  diaphragm, to reach the gland (see Fig. 25.4).   Renal arteries are large arteries which arise from the  abdominal aorta just below the level of origin of the   superior mesenteric artery. The right renal artery passes  laterally behind the inferior vena cava to reach the  hilum of the right kidney. The left renal artery runs  behind the left renal vein, and the splenic vein. Each  artery gives off the inferior suprarenal and ureteral  branches, and is then distributed to the kidney (Fig. 27.1).   Gonadal arteries are small and arise from the front of  the aorta a little below the origin of the renal arteries.  Each artery runs downwards and slightly laterally on  the psoas major. On the right side the artery crosses in  front of the inferior vena cava, the ureter and the  genitofemoral nerve. It passes deep to the ileum. On  the left side the artery crosses in front of the ureter and  the genitofemoral nerve; and passes deep to the colon  (see Figs 24.24 and 24.25).   The testicular artery joins the spermatic cord at the  deep inguinal ring, and traverses the inguinal canal.  Within the cord, it lies anterior to the ductus deferens.  At the upper pole of the testis, it breaks up into branches  which supply the testis and the epididymis.   The ovarian artery crosses the external iliac vessels at  the pelvic brim to enter the suspensory or infundi-  bulopelvic ligament of the ovary. It thus enters the  broad ligament and runs below the uterine tube to reach  the ovary through the mesovarium. The artery gives a  branch which continues medially to anastomose with  the uterine artery, and supplies twigs to the uterine tube  and to the pelvic part of the ureter (see Fig. 31.4).   Four pairs of lumbar arteries arise from the aorta  opposite the bodies of the upper four lumbar vertebrae.  The small, fifth pair is usually represented by the  lumbar branches of the iliolumbar arteries.   The upper four lumbar arteries run across the sides  of the bodies of the upper four lumbar vertebrae,  passing deep to the crura (upper arteries only), deep to  the psoas major and the quadratus lumborum to end  in small branches between the transversus and internal  oblique muscles. Each artery gives off a dorsal branch,  which arises at the root of the transverse process. The  dorsal branch gives off a spinal branch to the vertebral  canal, and then runs backwards to supply the muscles  and skin of the back.   Median sacral artery represents the continuation of the  primitive dorsal aorta. It arises from the back of the  aorta just above the bifurcation of the latter, and runs  downwards to end in front of the coccyx. It supplies  the rectum and anastomoses with the iliolumbar and  lateral sacral arteries.   These are the terminal branches of the abdominal aorta,  beginning in front of vertebra L4,1.25 cm to the left of  the median plane. On each side it passes downwards  and laterally and ends in front of the sacroiliac joint, at  the level of the lumbosacral intervertebral disc, by  dividing into the external and internal iliac arteries.   The right common iliac artery passes in front of the  commencement of the inferior vena cava. The right  common iliac vein is posterior to the vena cava above,  and medial to it below (Fig. 27.1).   The left common iliac artery is shorter than the right  artery. It is crossed at its middle by the inferior  mesenteric vessels. The left common iliac vein is medial  to it. The structures lying on the left ala of the sacrum,  i.e. sympathetic trunk, lumbosacral trunk, into lumbar  artery and obturator nerve are deep to it.   The inferior vena cava is formed by the union of the  right and left common iliac veins on the right side of  the body of vertebra L5. It ascends in front of the  vertebral column, on the right side of the aorta, grooves  the posterior surface of the liver, pierces the central  tendon of the diaphragm at the level of vertebra T8,  and opens into the lower and posterior part of the right  atrium (see Fig. 26.1).   Above, the right crus of the diaphragm is separated  from the inferior vena cava by the right renal artery,  the right coeliac ganglion, and the medial part of the  right suprarenal gland. Below, it is related to the right  sympathetic chain and to the medial border of the right  psoas.   1 The common iliac veins formed by the union of the  external and internal iliac veins unite to form the  inferior vena cava. Each vein receives an iliolumbar  vein. The median sacral vein joins the left common  iliac vein (Fig. 27.1).   The third and fourth lumbar veins run along with the  corresponding arteries and open into the posterior    aspect of the inferior vena cava. The veins of the left  side cross behind the aorta to reach the vena cava.  The first and second lumbar veins end in the  ascending lumbar vein, on the right and the left sides.   The ascending lumbar vein is an anastomotic  channel which connects the lateral sacral, iliolumbar,  and the subcostal veins. It lies within the psoas  muscle, in front of the roots of the transverse  processes of the lumbar vertebrae. On joining the  subcostal vein it forms the azygos vein on the right  side, and the hemiazygos vein on the left side.   3 The right testicular or ovarian vein opens into the  inferior vena cava just below the entrance of the renal  veins. The left gonadal vein drains into the left renal vein  (Fig. 27.1).   4 Th e renal veins join the inferior vena cava just below  the transpyloric plane. Each renal vein lies in front  of the corresponding artery. The right vein is shorter  than the left and lies behind the second part of  the duodenum. The left vein crosses in front of the  aorta, and lies behind the pancreas and the splenic  vein. It receives the left suprarenal and gonadal veins  (Fig. 27.1).   5 The right suprarenal vein is extremely short. It emerges  from the hi! uni of the gland and soon opens into the  inferior vena cava. The left suprarenal vein opens  into the left renal vein.   6 The hepatic veins are three large and many small veins  which open directly into the anterior surface of the  inferior vena cava just before it pierces the  diaphragm. These act as important support of liver  (see Fig. 23.27).    Thrombosis in the inferior vena cava causes oedema  of the legs and back. The collateral venous circulation  between the superior and inferior venae cavae is  established through the superficial or deep veins, or  both. The participating main superficial veins include  the (i) superficial epigastric, (ii) lateral thoracic,  (iii) thoracoepigastric. Other veins are internal  thoracic, posterior intercostal, external pudendal and  lumbo-vertebral veins (Fig. 27.2). The deep veins are  the azygos, hemiazygos and lumbar veins. The  vertebral venous plexus may also provide an effective  collateral circulation between the two venae cavae.   Abdominal aneurysm's (dilatation of the vessel)  most common site is between the renal arteries and  bifurcation of the abdominal aorta).   These veins usually begin in the abdomen. The azygos  vein arise from the posterior surface of the inferior vena    Dilated veins  joining each other  in obstruction of  superior vena cava    Fig. 27.2: Dilated veins in obstruction of superior vena cava  and inferior vena cava    cava near the renal veins; may be formed by the union  of the right ascending lumbar vein and the right  subcostal vein. It enters the thorax by passing through  the aortic opening of the diaphragm.   The hemiazygos vein is the mirror image of the lower  part of the azygos vein. It arise from the posterior  surface of the left renal vein, or may be formed by the  union of the left ascending lumbar vein and the left  subcostal vein. It enters the thorax by piercing the left  crus of the diaphragm.   These are the external iliac, common iliac and lumbar  or aortic nodes.   The external iliac nodes 8 to 10 lie along the external  iliac vessels, being lateral, medial and anterior to them.  They receive afferents from:   2 Deeper layers of the infraumbilical part of the  anterior abdominal wall   Their efferents pass to common iliac nodes. The  inferior epigastric and circumflex iliac nodes are  outlying members of the external iliac group.   The common iliac nodes , 4 to 6 in number lie along the  common iliac artery below the bifurcation of the aorta in  front of vertebra L5 or in front of the sacral promontory.  They receive afferents from the external and internal  iliac nodes, and send their efferents to the lateral aortic  nodes (Fig. 27.1).   The lumbar or aortic nodes are divided into preaortic  and lateral aortic groups. The preaortic nodes lie directly   anterior to the abdominal aorta, and are divisible into  coeliac, superior mesenteric and inferior mesenteric  groups. They receive afferents from intermediate nodes  associated with the subdiaphragmatic part of the  gastrointestinal tract, the liver, the pancreas and the  spleen (Fig. 27.1). Their efferents form the intestinal  trunks which enter the cistema chyli.   The lateral aortic nodes lie on each side of the  abdominal aorta. They receive afferents from the  structures supplied by the lateral and dorsal branches  of the aorta and form the common iliac nodes. Their  efferents from a lumbar trunk on each side, both of which  terminate in the cistema chyli (Fig. 27.1).   This is an elongated lymphatic sac, about 5 to 7 cm long.  It is situated in front of the first and second lumbar  vertebrae, immediately to the right of the abdominal  aorta. It is overlapped by the right crus of the  diaphragm. Its upper end is continuous with the  thoracic duct. It is joined by the right and left lumbar  and intestinal lymph trunks.   The lumbar trunks arise from the lateral aortic nodes,  and bring lymph from the lower limbs, the pelvic wall    and viscera, the kidneys, the suprarenal glands, the  testes or ovaries, and the deeper parts of the abdominal  wall. The intestinal trunks bring lymph from the  stomach, the intestine, the pancreas, the spleen, and the  anteroinferior part of the liver.   These are the psoas major, the psoas minor, the iliacus  and the quadratus lumborum. Their attachments are  given in Table 27.1 and their nerve supply and actions  are given in Table 27.2. Some additional facts about the  psoas major (Fig. 27.3) are given below.   The uppermost part of the psoas major lies in the  posterior mediastinum, and is related anteriorly to the  diaphragm and pleura.   1 Medial lumbocostal arch or medial arcuate ligament  and psoas fascia (see Fig. 24.4).   This is a fusiform muscle placed on  the side of the lumbar spine and  along the brim of the pelvis. The  psoas and the iliacus are together  known as the iliopsoas, due to their  common insertion and actions  (Fig. 27.3)   This is a small muscle which lies in  front of the psoas major. It is  frequently absent   From anterior surfaces and lower  borders of transverse process of all  lumbar vertebrae (see Fig. 15.3)   By 5 slips, one each from the bodies  of two adjacent vertebrae and their  intervertebral discs, from vertebrae,  T12 to L5   From 4 tendinous arches extending  across the constricted parts of the  bodies of lumbar vertebrae, between  the preceding slips. The origin is a  continuous one from the lower border  of T12 to upper border of L5   The muscle passes behind the inguinal  ligament and in front of the hip joint to  enter the thigh. It ends in a tendon which  receives the fibres of the iliacus on its  lateral side. It is then inserted into the  tip and medial part of the anterior surface  of the lesser trochanter of the femur   b. Inner lip of the iliac crest and the  ventral sacroiliac and iliolumbar  ligaments    The muscle ends in a long, flat tendon  which is inserted into the pecten pubis  and the iliopubic eminence   Lateral part of anterior surface of the  lesser trochanter. The insertion extends  for 2.5 cm below the trochanter   This is a quadrate muscle lying in  the lumbar region. Its origin lies  below and the insertion is above  (see Fig. 24.4)   c. Adjoining 5 cm of the inner lip of the  iliac crest (see Fig. 2.3)   b. Medial half of the lower border of  anterior surface of the 12th rib   Table 27.2: Nerve supply and actions of muscles of the posterior abdominal wall    Branches from the roots of spinal nerve  L2, L3 and sometimes L4.    Branches from spinal nerve LI  Branches from femoral nerve (L2, 3)  Ventral rami of spinal nerves T12 to L4    1. With the iliacus, it acts as a powerful flexor of the hip,  joint as in raising the trunk from recumbent to sitting  posture   2. Helps in maintaining stability at the hip. Balances the  trunk while sitting   3. When the muscle of one side acts alone, it brings  about lateral flexion of the trunk on that side   4. It is a weak medial rotator of the hip. After fracture of  the neck of the femur, the limb rotates laterally   1. Fixes the last rib during inspiration so that the  contraction of the diaphragm takes place more  effectively   2. When the pelvis is fixed, it may cause lateral flexion  of the vertebral column   3. The muscles of both sides acting together can extend  the lumbar vertebral column   7 Inferior vena cava and the terminal ileum on the right  side.   2 Lumbar plexus lies in substance of the muscle.  The medial surface is related to:   Posteriorly: Capsule of hip joint separated by a bursa.  Medially: Pectineus and femoral vein.    Psoas abscess: The psoas is enclosed in the psoas  sheath, a part of the lumbar fascia. Pus from  tubercular infection of the thoracic and lumbar  vertebrae may track down through the sheath into  the thigh, producing a soft swelling in the femoral  triangle (Fig. 27.4).   The typical posture of a laterally rotated lower  limb following fracture of the neck of the femur is  produced by contraction of the psoas muscle.   Lumbar fascia is the fascia enclosing the deep muscles  of the back ( see Fig. 24.11). It is made up of three layers—  posterior, middle and anterior. The posterior layer is  thickest and the anterior layer thinnest.   The posterior layer covers the loin and is continued  upwards on the back of the thorax and neck. The middle  and anterior layers are confined to the lumbar region.   • Medially, the posterior layer is attached to the tips of  the lumbar and sacral spines and the interspinous  ligaments.   • Laterally, it blends with the middle layer at the lateral  border of the erector spinae.   • Superiorly, it continues on to the back of the thorax  where it is attached to the vertebral spines and the  angles of the ribs.   • Inferiorly, it is attached to the posterior one-fourth of  the outer lip of the iliac crest.   • Medially, the middle layer is attached to the tips of  the lumbar transverse processes and the inter-  transverse ligaments.   • Laterally, it blends with the anterior layer at the lateral  border of the quadratus lumborum.   • Superiorly, it is attached to the lower border of the  12th rib and to the lumbocostal ligament.   • Inferiorly, it is attached to the posterior part of the  intermediate area of the iliac crest.   • Medially, the anterior layer is attached to the vertical  ridges on the anterior surface of the lumbar  transverse processes.   • Laterally, it blends with the middle layer at the lateral  border of the quadratus lumborum.   • Superiorly, it forms the lateral arcuate ligament,  extending from the tip of the first lumbar transverse  process to the 12th rib.   • Inferiorly, it is attached to the inner lip of the iliac  crest and the iliolumbar ligament ( see Fig. 24.11).   The lumbar plexus lies in the posterior part of the  substance of the psoas major muscle. It is formed by  the ventral rami of the upper four lumbar nerves ( see  Fig. 3.3). The first lumbar nerve receives a contribution  from the subcostal nerve, and the fourth lumbar nerve  gives a contribution to the lumbosacral trunk; which  takes part in the formation of the sacral plexus. The  branches of the lumbar plexus are summarized.   The iliohypogastric nerve (LI) emerges at the lateral  border of the psoas, runs downwards and laterally in  front of the quadratus lumborum, and behind the  kidney and colon, pierces the transversus abdominis a  little above the iliac crest, and runs in the abdominal  wall supplying the anterolateral muscles.   The ilioinguinal nerve (LI) has the same course as the  iliohypogastric nerve, but on a slightly lower level. It  exits through superficial inguinal ring.   The genitofemoral nerve (LI, L2 ventral divisions)  emerges on the anterior surface of the psoas muscle  near its medial border and runs downwards in front of  the muscle. Near the deep inguinal ring it divides into  femoral and genital branches. The femoral branch passes  through the arterial compartment of the femoral sheath  and is distributed to the skin of the upper part of the  front of the thigh. The genital branch pierces the psoas  sheath and enters the inguinal canal through the deep  inguinal ring. In the male, it supplies the cremaster  muscle, and in the female, it gives sensory branches to  the round ligament of the uterus and to the skin of the  labium majus (see Fig. 16.18).   The lateral cutaneous nerve of the thigh (L2, L3; dorsal  divisions) emerges at the lateral border of the psoas.   runs downwards and laterally across the right iliac  fossa, over the iliacus and reaches the anterior superior  iliac spine. Here it enters the thigh by passing behind  the lateral end of the inguinal ligament ( see Fig. 3.3).   The femoral nerve (L2, L3, L4; dorsal divisions) emerges  at the lateral border of the psoas below the iliac crest,  and runs downwards and slightly laterally in the  furrow between the psoas and iliacus. It lies under cover  of the fascia iliaca. It passes deep to the inguinal  ligament to enter the thigh lying on the lateral side of  the femoral sheath. Before entering the thigh it supplies  the iliacus and pectineus. In thigh it supplies quadriceps  femoris and sartorius (see Fig. 3.26).   The obturator nerve (L2, L3, L4; ventral divisions)  emerges on the medial side of the psoas muscle and  runs forwards and downwards on the pelvic wall,  below the pelvic brim. Near its commencement it is  crossed by the internal iliac vessels and the ureter. It  enters the thigh by passing through the obturator canal.  It supplies 3 adductor muscles, obturator externus and  gracilis (see Fig. 4.4).   The lumbosacral trunk (L4, L5; ventral rami) is formed  by union of the descending branch of nerve L4 with  nerve L5. It enters the lesser pelvis by passing over and  grooving the lateral part of the ala of the sacrum,  posterior to the common iliac vessels and the medial  part of the psoas. It is related medially to the  sympathetic chain; and laterally to the iliolumbar artery  and the obturator nerve (see Fig. 15.11). In the pelvis, it  takes part in the formation of the sacral plexus.   The abdomen is supplied by both sympathetic and  parasympathetic nerves. The sympathetic nerves are  derived from two sources.   1 The lumbar sympathetic trunk supplies somatic  branches to the lower abdominal wall and the lower  limb; and visceral branches for the pelvic organs  (Fig. 27.5).   2 The coeliac plexus, formed by splanchnic nerves  from the thorax, supplies all the abdominal organs,  including the gonads.    Fig. 27.5: Transverse section through the lumbar region  showing location of the lumbar sympathetic chain   This is ganglionated chain situated on either side of the  bodies of the lumbar vertebrae containing five ganglia.   The lumbar sympathetic chain is continuous with  the thoracic part deep to the medial arcuate ligament.  It runs vertically downwards along the medial margin  of the psoas major, and across the lumbar vessels. On  the right side, it is overlapped by the inferior vena cava,  and on the left by the lateral aortic lymph nodes.   The lumbar chain ends by becoming continuous with  the sacral part of the sympathetic chain behind the  common iliac vessels.   The anterior primary rami of the first and second  lumbar nerves send white rami communicans to the  corresponding ganglia.   All the five lumbar nerves receive grey rami  communicans from the corresponding lumbar ganglia.  The grey rami carry fibres which are distributed to the  lower abdominal wall and to the lower limb (Fig. 27.6).   The lumbar splanchnic nerves are generally four in  number. The upper two join the coeliac and aortic  plexuses, and the lower two join the superior hypo¬  gastric plexus.   The coeliac ganglion (Fig. 27.7) is the largest ganglion in  the body, situated one on each side of the coeliac trunk.  Each ganglion is irregular in shape and is usually  divided into a larger upper part which receives the  greater splanchnic nerve, and a smaller lower part;  aorticorenal ganglion which receives the lesser  splanchnic nerve.   The coeliac plexus or solar plexus (Fig. 27.7) is closely  related to the coeliac ganglion. The plexus is situated on    Fig. 27.6: The lumbar sympathetic chain and its branches.  L1-L5 = lumbar spinal nerves; and G = lumbar sympathetic  ganglion    Fig. 27.7: Scheme to show the connections of the coeliac,  superior hypogastric and inferior hypogastric plexuses    the aorta around the coeliac trunk and around the root  of the superior mesenteric artery. The plexus extends on  to the crura of the diaphragm. It is overlapped by the    inferior vena cava and by the pancreas. The fibres making  up the plexus are as follows: ’   a. Preganglionic sympathetic fibres reach it through  the greater and lesser splanchnic nerves.   c. Preganglionic vagal fibres are derived from the  posterior vagal trunk containing fibres from both  the right and left vagal nerves. The fibres from  the right vagus predominate.   d. Sensory fibres from the diaphragm reach the  coeliac plexus along the inferior phrenic arteries.   The coeliac plexus forms a number of secondary  plexuses which surround branches of the aorta.   1 The phrenic plexus passes along the inferior phrenic  artery to the suprarenal gland. The right phrenic  plexus contains a right phrenic ganglion.   2 The hepatic plexus is distributed to the liver, the  gallbladder and the bile ducts.   4 The splenic plexus supplies the vessels and smooth  muscle of the spleen.   5 The suprarenal plexus contains preganglionic fibres ,  that end in relation to the chromaffin cells of the  suprarenal gland. These cells are homologous with  postganglionic sympathetic neurons.   6 The renal plexus is formed by filaments from the  coeliac plexus, the aorticorenal ganglion, the lowest  thoracic splanchnic nerve, the first lumbar  splanchnic nerve and the aortic plexus. It supplies  the kidney and the upper part of the ureter.   7 The testicular plexus supplies the testis, the  epididymis and the vas deferens.   8 The ovarian plexus supplies the ovary and the uterine  tube.   9 The superior mesenteric plexus contains a superior  mesenteric ganglion, and supplies the territory of  the superior mesenteric artery.   10 The abdominal aortic plexus or intermesenteric plexus  is formed by the coeliac plexus and filaments from  the first and second lumbar splanchnic nerves  (Fig. 27.8). It is situated on the sides and the front of  the aorta, between the origins of the superior and  inferior mesenteric arteries. Actually it is made up of  four to twelve intermesenteric nerves connected by  oblique filaments. It is continuous above with the  coeliac plexus and below with the superior  hypogastric plexus. Its branches form parts of the  testicular, inferior mesenteric, iliac and superior  hypogastric plexuses, and supply the inferior vena  cava.    The inferior mesenteric plexus is formed chiefly by  fibres from the aortic plexus. It is distributed to the  territory of the inferior mesenteric artery.   The superior hypogastric plexus lies in front of the  bifurcation of the abdominal aorta, the left common iliac  vein, the median sacral vessels, the body of fifth lumbar  vertebra, the promontory of the sacrum, and between  the two common iliac arteries. Though it is often called  the presacral nerve, it is neither a single nerve nor  presacral in position. The plexus lies more towards the  left, and contains scattered nerve cells (Fig. 27.8).   1 Inferiorly, the plexus divides into the right and left  hypogastric nerves which descend into the pelvis and  form the two inferior hypogastric plexuses.   2 Superiorly, the hypogastric plexus also gives off  branches to the ureteric, testicular or ovarian, and  the common iliac plexuses.   There are two plexuses, right and left. Each inferior  hypogastric or pelvic plexus lies in the extraperitoneal  connective tissue of the pelvis. In the male, it lies on  the side of the rectum, the seminal vesicle, the prostate  and the posterior part of the urinary bladder. In the  female, it lies on the side of the rectum, the cervix, the  vaginal fornix and the posterior part of the urinary  bladder; and also extends into the base of the broad  ligament of the uterus. The plexus contains numerous  small ganglia. The fibres forming the inferior  hypogastric plexuses are as follows:   1 These are chiefly derived from the hypogastric nerve  which is represented either by a single nerve or by a  plexus.   These are derived from the pelvic splanchnic nerves.  They relay in the walls of the viscera supplied.  Branches   Branches from the inferior hypogastric plexus are  distributed to the pelvic viscera and some abdominal  viscera, either directly or along the branches of the  internal iliac artery.   As already noted the parasympathetic supply of the  abdomen proper, comes from the vagi, and of the pelvis  and hindgut from the pelvic splanchnic nerves or nervi  erigentes (S2, S3, S4). These fibres are distributed  through the coeliac and inferior hypogastric plexuses  respectively.   Fibres from the pelvic splanchnic nerves reach it  through the inferior hypogastric plexus. Usually these  fibres ascend through the left part of the superior  hypogastric plexus, cross the sigmoid and left colic  vessels, and are distributed along the vessels as well as  independently to the derivatives of the hindgut.   In general, the sympathetic nerves are vasomotor, motor  to sphincters, inhibitory to peristalsis, and sensory to  all the viscera supplied. The parasympathetic nerves , on  the other hand, are motor and secretomotor to the gut  and the glands associated with it.    The following 6 layers in the abdomen are shown in  Figs 27.9 to 27.14.    • Visceral pain: Viscera are insensitive to cutting,  crushing or burning. However, visceral pain is  caused by:   * The pain felt in the region of the viscus itself is  known as true visceral pain. It is poorly localized  and is dull or heavy. Pain arising in viscera may  also be felt in the skin or other somatic tissues,  supplied by somatic nerves arising from the same  spinal segment. This kind of pain is called  referred pain . If the inflammation spreads from a  diseased viscus to the parietal peritoneum it  causes local somatic pain in the overlying body wall  (Fig. 27.15).   Viscera usually have low amount of sensory  output, whereas skin is an area of high amount of  sensory output. So pain arising from low sensory  output area is projected as coming from high  sensory output area.   Iliac veins  Lumbar veins  Testicular veins  Renal veins  Suprarenal veins  Hepatic veins   - 3 ventral unpaired visceral: Coeliac axis, superior  mesenteric and inferior mesenteric arteries   - 4 lateral paired visceral: Inferior phrenic, middle  suprarenal, renal and gonadal arteries   • Coeliac plexus is chiefly sympathetic. It also  contains fibres of parasympathetic system through  vagus nerve.   • Pelvic splanchnic nerves arise from S2, S3 and S4  segments and supply parasympathetic fibres to the  distal parts of digestive tube, urinary bladder,  urethra, prostate including the genital organs.    A middle aged person complains of low backache  for few months. Later he developed a soft swelling  in the upper medial part of thigh   Ans: The soft swelling in the thigh can be enlarged  inguinal lymph nodes, a hernia, varicose vein or  psoas abscess.   Enlarged lymph nodes can be excluded after a  course of antibiotics.   Varicose veins can be seen in the rest of the lower  limb.   Psoas abscess: History of low backache with X-  ray showing vertebral pathology. Pus from  tubercular lumbar vertebrae tracks down through  the psoas sheath into the thigh, producing a soft  swelling in femoral triangle. He needs to be given  antitubercular treatment for full period under the  supervision of a physician.   Perineum is the region at the lower end of the trunk, in  the interval between the two thighs. The external  genitalia are located, in the perineum. The perineum  forms the lower division of the pelvis that lies below  the pelvic diaphragm, formed by the levator ani and  coccygeus, and fills in the pelvic outlet or inferior  aperture of the pelvis.   In males there are two openings, one of the  gastrointestinal system and the other being the common  opening of urinary and genital system. In females there  are three separate openings, one each of the  gastrointestinal, genital and urinary systems. The  perineal body supports the reproductive system. Its  injury without repair, may lead to prolapse of the  uterus. Pudendal nerve supplies muscles, skin, mucous  membrane of both anal and urogenital triangles  comprising the perineum. Pudendum means "to be  ashamed of".   Anteriorly: The scrotum in males, and the mons pubis  in females (Figs 28.1 and 28.2).    Fig. 28.1: The male perineum. Interrupted lines indicate the  outlines of pelvic outlet   Urethral orifice  Labia majora  Labia minora  Vaginal orifice  Gluteal fold  Anus   Fig. 28.2: The female perineum. Interrupted lines indicate the  position of pelvic outlet   On each side: The upper part of the medial side of the thigh.   The deep boundaries of the perineum are the same as  those of the pelvic outlet.   Anteriorly: Upper part of the pubic arch and the arcuate  or inferior pubic ligament (Fig. 28.3).   A transverse line joining the anterior parts of the ischial  tuberosities, and passing immediately anterior to the  anus, divides the perineum into two triangular areas, a  posterior, anal region or triangle, and an anterior,  urogenital region or triangle (Fig. 28.3).   The anal region contains the termination of the anal  canal in the median plane and an ischioanal fossa on  each side.    Fig. 28.3: Boundaries of perineum. Interrupted line shows the  division of perineum into urogenital and anal regions    Urogenital region contains the external urogenital  organs. In males, the urethra enclosed in the root of  penis, partly hidden anteriorly by the scrotum; and in  females, the female external genital organs.   In the urogenital region, there are the superficial  perineal space or pouch and the deep perineal space or  pouch.   The chief neurovascular bundle of the perineum  occupies a fascial tunnel, the pudendal canal, and  contains the pudendal nerve and the internal pudendal  vessels. The pudendal canal lies in the lateral wall of  the ischioanal fossa.    Identify the openings of urethra, anal canal and vagina  if it is a female cadaver. Define perineal body in the centre  of perineum. Dissect the parts of external anal sphincter.   Pass a forceps downwards and backwards deep to  the membranous layer of the superficial fascia of the  anterior abdominal wall.   In the male, expose the membranous layer in the  perineum. Make an incision in the membranous layer  on one side and dissect the ischiocavernosus,  bulbospongiosus and superficial transverse perinei  muscles, nerves, blood vessels present in the superficial  perineal space. The posterior scrotal/labial vessels  and nerves pierce the posterolateral corner of perineal  membrane to enter the superficial perineal space  (Fig. 28.4).   In the female, remove the fat from the labium majus  and expose the membranous layer. Incise it and expose  the posterior part of this space and all its contents both  in the male and female cadavers. Note the posterior  limit where the membranous layer passes superiorly to  fuse with the perineal membrane. Identify the various  female external genital organs.   Identify the structures piercing the perineal  membrane in both male and female. Note the ill-defined  nature of the perineal membrane in female as it is  pierced by vagina in addition to urethra.   Dissect the inferior rectal vessels and nerve and follow  them to the lateral wall of the ischioanal fossa. Remove  the fat from the ischioanal fossa. Identify and trace the  pudendal nerve and vessels in the fascial pudendal canal  on the lateral wall of the ischioanal fossa.   Clean the sacrotuberous and sacrospinous ligaments.  Identify coccyx in the midline posteriorly and locate the  ischial tuberosity. Define the ischiopubic rami till the  lower margins of pubic symphysis anteriorly.   The inferior rectal nerve (S2, S3, S4) supplies the skin  around the anus and over the ischioanal fossa. The  perineal branch of the fourth sacral nerve supplies the skin  posterior to the anus.   It contains a large amount of fat which fills the  ischioanal fossa.   It is formed by the inferior fascia of the pelvic  diaphragm and the fascia covering the obturator  internus below the attachment of the levator ani.   It is a fibrofatty mass permeated with muscle fibres  derived from the levator ani and the external anal  sphincter. It extends from the anus to the tip of the  coccyx, and supports the rectum (Fig. 28.4).   The perineal body, or the central point of the perineum,  is a fibromuscular node situated in the median plane,  about 1.25 cm in front of the anal margin and close to  the bulb of the penis. Ten muscles of the perineum  converge and interlace in the perineal body.   All these converge and interlace in the perineal body.  Nine are visible in Fig. 28.4. Last one is unstriped fibres  of longitudinal muscle coat of the anal canal.   The perineal body is very important in the female  for support of the pelvic organs. Sphincter urethro-  vaginalis in female is also attached here. It may be  damaged during parturition or childbirth. This may  result in prolapse of the urinary bladder, the uterus,  the ovaries and even of the rectum.   Anal canal is surrounded in its upper three-fourths by  the internal anal sphincter which ends below at the level  of white line of Hilton (Fig. 28.5).   The external anal sphincter surrounds the whole  length of the anal canal. It is supplied by the inferior  rectal nerve and by the perineal branch of the fourth  sacral nerve. It is under voluntary control and keeps  the anus and anal canal closed. It is described in detail  in Chapter 33.   The ischioanal fossa is a wedge-shaped space situated  one on each side of the anal canal below the pelvic  diaphragm. Its base is directed downwards, towards  the surface. The apex is directed upwards.    Length (anteroposteriorly), 5 cm; width (side to side),  2.5 cm; and depth (vertically), 5 to 6.2 cm.   The apex is formed by the line where the obturator  fascia meets the inferior fascia of the pelvic diaphragm  or anal fascia. The line corresponds to the origin of the  levator ani from the lateral pelvic wall.   Anteriorly , the fossa is limited by the posterior border  of the perineal membrane (but for the anterior recess  of the fossa) (Fig. 28.6).   b. Medial surface of the ischial tuberosity, below the  attachment of obturator fascia (Fig. 28.7).   The medial wall slopes upwards and laterally, and is  formed by:   a. The external anal sphincter, with the fascia  covering it in the lower part.   b. The levator ani with the anal fascia in the upper  part (Fig. 28.7).    Fig. 28.6: Surface view of the ischioanal fossa, and perineal  membrane    Perianal space filled with fat (small loculi)  Fig. 28.7: Coronal section through the ischioanal fossa   1 The anterior recess extends forwards above the  perineal membrane, reaching almost up to the  posterior surface of the body of the pubis. It is closely  related to the prostate or the vagina (Fig. 28.8).   2 The posterior recess is smaller than the anterior. It  extends deep to sacrotuberous ligament.   3 The horseshoe recess connects the two ischioanal  fossae behind the anal canal (Fig. 28.6).   The perianal fascia is in the form of a septum that passes  laterally from the lower end of the longitudinal coat of  the anal canal. It extends medially from the white line  of Hilton to the pudendal canal laterally. It separates a  shallow subcutaneous perianal space from the deep  ischioanal space. The fat in the perianal space is tightly  arranged in small loculi formed by complete septa. The  infections of this space are, therefore, very painful due  to the tension caused by swelling.   This is large and deep. The fat in this space is loosely  arranged in large loculi formed by incomplete delicate  septa. The infections of this space are, therefore, least   Fig. 28.8: Parasagittal section through the ischioanal fossa, showing its recesses   The lunate fascia arches over the ischioanal fat. It  begins laterally at the pudendal canal and merges  medially with the fascia covering the deep part of the  external anal sphincter. The fascia divides the ischioanal  space into:   This is a fascial canal in the lateral wall of the ischioanal  fossa, enclosing the pudendal nerve and internal  pudendal vessels. The fascia of the canal is fused with  the lower part of the obturator fascia laterally, with the  lunate fascia above, with the perianal fascia medially,  and with the falciform process of the sacrotuberous  ligament below.   2 Inferior rectal nerve and vessels. They pass through  the fossa from lateral to medial side. They arch  upwards above the fat (Fig. 28.9) to supply mucous  membrane, external sphincter and the skin around  the anus.   3 Pudendal canal with its contents. This canal lies along  the lateral wall of the fossa (Fig. 28.7).   4 Posterior scrotal or posterior labial (in females)  nerves and vessels. They cross the anterolateral part  of the fossa and enter the urogenital triangle.   5 Perineal branch of the fourth sacral (S4) nerve. It  enters the posterior angle of the fossa and runs over  the levator ani to the external anal sphincter.   6 Perforating cutaneous branches of nerves S2, S3.  They appear at the lower border of the gluteus  maximus, in the posterior part of the fossa.    Fig. 28.9: Surface view of the ischiorectal fossa, showing some  of its contents    * The two ischioanal fossae allow distention of the  rectum and anal canal during passage of faeces.   * Both the perianal and ischioanal spaces are  common sites of abscesses (Fig. 28.10).   Sometimes an abscess may burst into the anal  canal or rectum internally, and on to the surface  of the perineum externally. In this way an  ischioanal type of anorectal fistula or fistula in ano  may be produced. The most common site of the  internal opening is in the floor of one of the anal  crypts. If the abscess bursts only externally, and  healing does not follow, an external sinus is  produced, Through the horseshoe recess a  unilateral abscess may become bilateral.   ■ The ischioanal fat acts as a cushion-like support  to the rectum and anal canal. Loss of this fat in  debilitating diseases like diarrhoea in children  may result in prolapse of the rectum.   * The occasional gap between the tendinous origin  of levator ani and the obturator fascia is known  as hiatus of Schwalbe. Rarely pelvic organs may  herniate through this gap into the ischioanal fossa,  resulting in an ischioanal hernia.   Place a finger in the ischioanal fossa and push it gently  forwards. It will pass easily above the urogenital  diaphragm, lateral to levator ani. Strip the ischio-  cavernosus muscles from the crus of the penis or  clitoris. Trace them to their termination.   Detach the superficial perineal muscles, including  right crus of the penis from the ischiopubic rami. Turn it  forwards to expose the deep artery and vein on the  superior surface of perineal membrane also called  inferior fascia of urogenital diaphragm.   In the male detach the bulb of the penis from the  central perineal tendon. Turn it forwards to expose the  urethra and the artery of the bulb.   In the female raise the posterior end of the bulb of  the vestibule to expose the greater vestibular gland.   Detach the perineal membrane from the pubic arch  on the right side. Carefully, reflect the membrane  medially to visualise the urethra and a pair of posteriorly  placed deep transversus perinei muscles.   Remove the exposed muscles of the deep perineal  space including the endopelvic fascia. Clean the area  to see the perineal surface of the levator ani.    Fig. 28.10: Ischiorectal type of fistula in ano. Internally it  usually opens into one of anal crypts. The track traverses  the superficial parts of external anal sphincter and lower part  of internal anal sphincter. A blind sinus lies high up in the  ischiorectal fossa   The anterior division of the perineum is the urogenital  region. It contains the superficial and deep perineal  spaces or pouches.    4 Posterior scrotal: These supply the skin of the medial  part of the urogenital region and the medial part of  the posterior two-thirds of the scrotum.   5 The mucous membrane of urethra is supplied by  the perineal branch of the pudendal nerve .    The cutaneous nerves of perineum are derived from  the sacral nerves (32, S3, S4). These segments also  supply parasympathetic fibres to the pelvic organs.  Diseases of these organs may, therefore, cause referred  pain in the perineum.   It is made up of two layers as in the lower part of the  anterior abdominal wall. The superficial fatty layer is  continuous with the superficial fascia of the  surrounding regions. The deep membranous layer or  Colles' fascia is attached posteriorly to the posterior  border of perineal membrane, and on each side to pubic  arch below the crus penis. Anteriorly, it is continuous  with the fascia of the scrotum containing the dartos,  fascia of the penis, and with the membranous layer of  the superficial fascia of the anterior abdominal wall or  fascia of Scarpa.   1 Dorsal nerve of penis : It supplies the skin of the penis,  except at its root (Fig. 28.11).   2 Ilioinguinal nerve and genital branch of the genitofemoral  nerve: These supply the skin of the anterior one-third  of the scrotum and the root of the penis.   3 Perineal branch of posterior cutaneous nerve of thigh: It  supplies the skin of the lateral part of the urogenital  region and the lateral part of the posterior two-thirds  of the scrotum.   It is also made up of one layer that lines the deep  perineal space inferiorly.   This fascia of the urogenital diaphragm is thick. It is  also called the perineal membrane.   The urogenital region is bounded posteriorly by the  interischial line which usually overlies the posterior  border of the transverse perinei muscles. Anteriorly and  laterally, it is bounded by symphysis pubis and  ischiopubic rami.   Urogenital region extends superficially to encompass  the scrotum and root of penis.   Urogenital region is divided into two parts by strong  perineal membrane.   Previous view: Space between superior fascia of  urogenital diaphragm and perineal membrane that  contained urethra and urethral sphincter.   Present view: Now the urethral sphincter is known to  be contained inside the urethra itself (within). The  urogenital diaphragm does not exist. The deep perineal  space is thin and open above (Fig. 28.12 and Table 28.1).   Urinary bladder  Prostate  Levator ani  Obturator internus  Bulbourethral gland  Perineal membrane  Deep transversus perinei    Fig. 28.12: Coronal section through the urogenital region of the male perineum   Pelvic fascia  Dorsal nerve of penis  Internal pudendal artery  Crus penis  Ischiocavernosus    a. Sphincter urethrae or distal urethral sphincter within  the wall of urethra   to the bulb of penis, urethral artery, deep and dorsal  arteries of penis   b. Stems of origin of four branches namely  artery to bulb of vestibule, urethral artery,  deep and dorsal arteries of clitoris   Superficial aspect: Perineal membrane. Between these  two fascial layers lie deep transverse perinei; superficial  to the proximal urethral sphincter mechanism and  pubourethralis (Fig. 28.12).   The previous view was that sphincter urethrae  extended between the two ischiopubic rami and was  pierced by urethra but as of now the sphincter urethrae  lies within wall of urethra as distal urethral sphincter.   These muscles do not form a true diaphragmatic  sheet as such because fibres from the several parts  extend through the visceral outlet in the pelvic floor    into the lower reaches of the pelvic cavity. (There is no  sphincter urethrae outside urethra. So, no urogenital  diaphragm exists).   Urethra, vessels and nerve to the bulb of penis,  bulbourethral glands, deep dorsal vessels and nerves  of penis, posterior scrotal vessels and nerves.   It forms an incomplete sheet of skeletal muscle  extending across the urogenital triangle from the medial  aspects of the ischiopubic rami. Posteriorly, the sheet   is attached to perineal body where its fibres decussate  with those of opposite side.   Anteriorly, the muscles are deficient and the visceral  structures pass across the endopelvic fascia and the  perineal membrane. Some fibres pass to the deep part  of external anal sphincter posteriorly and sphincter  urethrae (contained within the urethra).   Together with superficial transverse perinei the  muscles act to tether (hold) the perineal body in median  plane. The muscle gives dynamic support for pelvic  viscera.    Consists of intrinsic striated and smooth muscles of  urethra and the pubourethralis component of levator  ani which surrounds the urethra at the point of  maximum concentration of those muscles. It surrounds  the membranous urethra in the male.   Smooth muscle fibres also reach up to the lowest part  of the neck of the bladder and between the two, fibres  lie on the surface of prostate.   Bulk of fibres surround the membranous urethra.  There are circularly disposed striated muscle fibres  called rhabdosphincter which forms main part of distal  urethral sphincter mechanism (Fig. 28.12). Some fibres  are attached to inner surface of the ischiopubic ramus,  forming compressor urethrae.   • Apex attached to arcuate ligament of pubis, where  the membrane is attached to this arcuate ligament  of pubis, it is particularly thick and is called  transverse perineal ligament.   • Posterior border is fused to deep parts of perineal  body and is continuous with the fascia over deep  transversus perinei.   • Urethra 2-3 cm behind the inferior border of pubic  symphysis.    * The membranous part of the male urethra is the  narrowest and least dilatable part of the urethra.  In inexperienced hands, it is likely to be ruptured  during instrumentation. The urethra can also  rupture in accidental injuries.   • Rupture of the urethra leads to extravasation of  urine, which may be superficial or deep. In  superficial extravasation , the urine spreads  downwards deep to the membranous layer of the  superficial fascia. It first fills the superficial  perineal space; and then the scrotum, the penis  and the lower part of the anterior abdominal wall.  It is prevented from going to the ischioanal fossa  or the thigh by the firm attachment of the  membranous layer of superficial fascia to their  boundaries (Fig. 28.15).   In deep extravasation , the urine spreads upwards  into the extraperitoneal space of the pelvis around  bladder and prostate into the anterior abdominal  wall (Fig. 28.16).    Fig. 28.15: Extravasation of urine due to rupture of penile urethra    Fig. 28.16: Extravasation of urine due to rupture of membranous  urethra    It comprises of female external genital organs and  female urogenital region.   Mons pubis is a rounded eminence present in front of  the pubic symphysis. It is formed by accumulation of  subcutaneous fat. It is covered with pubic hair. The hair  bearing area has a nearly horizontal upper limit.   Labia majora are two thick folds of skin enclosing  fat. They form the lateral boundaries of the pudendal  deft. Their outer surfaces are covered with hair, and  the inner surfaces are studded with large sebaceous  glands. The larger anterior ends are connected to each  other below the mons pubis to form the anterior  commissure. The skin connecting the less prominent  posterior ends of the labia is known as the posterior   Prepuce of clitoris  Gians of clitoris  Urethral  Vestibule of vagina  Vestibular fossa  Anus   commissure . The area between the posterior commissure  and the anus which is about 2.5 cm long constitutes the  gynaecological perineum.   Labia minora are two thin folds of skin, which lie within  the pudendal cleft. Anteriorly, each labium minus splits  into two layers; the upper layer joins the corresponding  layer of the opposite side to form the prepuce of the  clitoris . Similarly the lower layers of the two sides join  to form the frenulum of the clitoris. Posteriorly, the two  labia minora meet to form the frenulum of the labia  minora. The inner surface of the labia minora contains  numerous sebaceous glands.   The clitoris is an erectile organ, homologous with the  penis. However, it is not traversed by urethra. It lies in  the anterior part of pudendal cleft. The body of clitoris  is made up of two corpora cavernosa enclosed in a fibrous  sheath and partly separated by an incomplete  pectiniform septum. The corpus spongiosum is absent . Each  corpus cavernosum is attached to the ischiopubic rami.  The down-turned free end of clitoris is formed by a  rounded tubercle, glans clitoridis, which caps the free  ends of corpora. The glans is made up of erectile tissue  continuous posteriorly with the commissural venous  plexus uniting right and left bulbs of vestibule called  bulbar commissure. The surface of glans is highly  sensitive and plays an important role in sexual responses.   Vestibule of the vagina is space between two labia  minora. It presents the following features.   1 The urethral orifice lies about 2.5 cm behind the clitoris  and just in front of the vaginal orifice.   2 Vaginal orifice or introitus lies in the posterior part of  the vestibule, and is partly closed, in the virgin, by a  thin membrane called the hymen. In married women,  the hymen is represented by rounded tags of tissue  called the carunculae hymenales.   3 Orifices of the ducts of greater vestibular glands lie one  on each side of vaginal orifice, between the hymen  and labium minus (Fig. 28.19).   4 Numerous lesser vestibular or mucous glands open on  the surface of vestibule.   5 The posterior part of vestibule between vaginal  orifice and frenulum of labia minora forms a shallow  depression known as vestibular fossa.   Bulbs of the vestibule are two oval bodies of erectile  tissue that correspond to the two halves of the bulb of  the penis. The bulbs lie on either side of the vaginal  and urethral orifices, superficial to the perineal    membrane. The tapering anterior ends of the bulbs are  united in front of the urethra by a venous plexus, called  the bulbar commissure. The expanded posterior ends of  the bulbs partly overlap the greater vestibular glands.   Greater vestibular glands are homologous with the  bulbourethral glands of Cowper in the male. These lie  in the superficial perineal space. Each gland has a long  duct about 2 cm long which opens at the side of the  hymen, between the hymen and the labium minus.   1 Dorsal nerve of clitoris. It supplies the skin of the  clitoris (Fig. 28.18).   2 Ilioinguinal nerve and genital branch of the genitofemoral  nerve. These supply the skin of the anterior one-third  of the labium majus.   3 Perineal branch of posterior cutaneous nerve of thigh: It  supplies the skin of the lateral part of the urogenital  region and the lateral part of the posterior two-thirds  of the labium majus.   4 Posterior scrotal or labial nerves: These supply the skin  of the medial part of the urogenital region including  the labium minus in females and the medial part of  the posterior two-thirds of the labium majus.   5 The mucous membrane of urethra is supplied by the  perineal branch of the pudendal nerve.    The cutaneous nerves of perineum are derived from  the sacral nerves (S2, S3, S4). These segments also  supply parasympathetic fibres to the pelvic organs.  Diseases of these organs may, therefore, cause referred  pain in the perineum.   It is made up of two layers as in the lower part of the  anterior abdominal wall. The superficial fatty layer is  continuous with the superficial fascia of the  surrounding regions. The deep membranous layer or  Colles' fascia is attached posteriorly to the posterior  border of perineal membrane, and on each side to pubic  arch below the crus penis. Anteriorly, it is continuous  with the fascia of the scrotum containing the dartos,  fascia of the penis, and with the membranous layer of  the superficial fascia of the anterior abdominal wall or  fascia of Scarpa.   It is also made up of one layer that lines the deep  perineal space interiorly.   This fascia of the urogenital diaphragm is thick. It is  also called the perineal membrane.   The urogenital region is bounded by the interischial  line which usually overlies the posterior border of the  transverse perinei muscles.   Anteriorly and laterally, it is bounded by symphysis  pubis and ischiopubic rami.   In the female, urogenital region extends to the labia  majora and mons pubis.   Previous view: Space between urogenital diaphragm and  perineal membrane that contained urethra and urethral  sphincter.   Present view: Now the urethral sphincter is known to  be contained inside the urethra itself (within). The   Previous view was that sphincter urethrae extended  between the two ischiopubic rami and was pierced by  urethra and vagina but as of now the sphincter urethrae  lies within urethra.   These muscles do not form a true diaphragmatic  sheet as such because fibres from the several parts  extend through the visceral outlet in the pelvic floor  into the lower reaches of the pelvic cavity. There is no  sphincter urethrae outside urethra. So no urogenital  diaphragm exists.   In female perineal membrane is less well defined and  divided into two halves by urethra and vagina so that  it forms triangle on two sides.   The pubourethral ligament links the two sides  anteriorly behind pubic arch.   Urethra, vagina, deep dorsal vessels and nerves of  clitoris, posterior labial vessels and nerves.   Consists of intrinsic smooth muscle, intrinsic skeletal  muscle. This is anatomically separate from the  pubourethralis component of levator ani.   The sphincter mechanism surrounds more than the  middle third of urethra. It blends above with the smooth  muscle of bladder neck and below with the smooth  muscle of lower urethra and vagina. Skeletal muscle  fibres are circularly disposed, called rhabdosphincter.   Uterine cervix  Pelvic fascia  Dorsal nerve of clitoris  Internal pudendal arten  Crus clitoris  Ischiocavernosus   Fig. 28.19: Coronal section through the urogenital region of the female perineum   This forms main part of external urethral sphincter.  This in reality is not distal but just urethral sphincter  mechanism, since there is no proximal urethral  sphincter in female (Fig. 28.20).   Compresses the urethra, particularly when bladder  contains fluid. It contracts to expel the final drops of  urine.   Compressor urethrae arises from ischiopubic rami of  each side by a small tendon. Fibres pass anteriorly to  meet their counterparts in a flat band which lies anterior  to urethra. A variable number of these fibres pass  medially to reach the lower wall of vagina. Sphincter  urethrae is within the wall of urethra (Fig. 28.21).   Sphincter urethrovaginalis arises from perineal body.  Its fibres pass forwards on either side of urethra and  vagina to meet their counterparts in a flat band,  anterior to urethra below compressor urethrae.   Direction of the fibres of compressor urethrae and  sphincter urethrovaginalis suggest that these produce  elongation as well as compression of the membranous  urethra and thus aid continence in females. Both are  supplied by perineal nerve.   • Urethra, 2-3 cm behind the inferior border of pubic  symphysis.    Fig. 28.21: Female perineum showing superficial muscles (left  half) and deep perineal muscles on right half   The arrangement of the superficial and deep fasciae in  the urogenital region results in the formation of two  triangular spaces, the superficial and deep perineal  spaces or pouches (Fig. 28.18).   The boundaries and contents of the deep space are  summarised in Table 28.1.   Table 28.2 summarises the boundaries and contents  of superficial perineal space.   These muscles are arranged in superficial and deep,  groups. The superficial muscles are the ischiocaver¬  nosus, the bulbospongiosus and the superficial  transversus perinei, described in Table 28.3. The deep  muscles are the distal urethral sphincter mechanism,  sphincter urethrae with extensions and the deep  transversus perinei (described earlier).   This is a fascial tunnel present in the lateral wall of the  ischioanal fossa, just above the sacrotuberous ligament.  It transmits the pudendal nerve and the internal  pudendal vessels.    The canal extends from the lesser sciatic notch to the  posterior border of the perineal membrane (Fig. 28.23).   The pudendal canal is a space between obturator fascia  and the lunate fascia. Others believe that it is formed  by splitting of the obturator fascia (Fig. 28.7).   1 Pudendal nerve (S2, S3, S4): In the posterior part of  the canal, pudendal nerve gives off the inferior rectal  nerve and then soon divides into a larger perineal  nerve and a smaller dorsal nerve of penis.   This is the superficial space of the urogenital  region situated superficial to the perineal  membrane   Open and continuous with the spaces of the  scrotum, penis and the anterior abdominal wall   Open and continuous with the spaces of the  clitoris and the anterior abdominal wall   Root of penis, made up of two corpora  cavernosa and one corpus spongiosum  traversed by the urethra (Fig. 28.12)   Body of clitoris, made up only of two corpora cavernosa  separated by an incomplete septum. The corpus spon¬  giosum is absent. Urethral orifice lies 2 cm behind  the clitoris. Vaginal orifice just behind urethral orifice.  Two bulbs of vestibule are there, one on each side of  these two orifices. These unite and get attached to the  glans clitoridis.   b. Bulbospongiosus covering corpus  spongiosum; both are united by a median  raphe   b. Bulbospongiosus covering bulb of vestibule. These  remain separated to give passage to urethra and  vagina (Fig. 28.19)   a. Three sets of branches from perineal nerve  namely posterior scrotal nerve, branch to  bulb and muscular branches   a. Three sets of branches from perineal nerve namely  posterior labial nerve, branch to bulb of vestibule  and muscular branches   a. Two branches of perineal artery namely, the  posterior scrotal and transverse perineal   b. Four branches from the artery of penis  namely, artery to the bulb of penis, urethral  artery, deep and dorsal arteries of penis   a. Two branches of perineal artery namely posterior  labial and transverse perineal   b. Four branches from the artery of clitoris, namely artery  to bulb of vestibule, urethral artery, deep and dorsal  arteries of clitoris   It covers the crus  penis or crus  clitoridis; smaller  in females b.    Medial surface  of ischial  ramus behind  the crus  Posterior part  of perineal  membrane    Inserted by an  aponeurosis into  the sides and  undersurface  of the anterior  part of the crus    Perineal branch It helps in maintaining  of pudendal erection of the penis by   It covers the bulb  of penis and the  two muscles are  united by a median  raphe    1. Helps in ejaculation  of semen and  ejecting the last  drops of urine   2. Middle fibres assist  in the erection of  the corpus spongio¬  sum penis by com¬  pressing the bulb   3. Anterior fibres also  help in the erection  of penis by com¬  pressing the deep  dorsal vein of penis   In females it acts as  sphincter of vagina and  assists in erection of  clitoris    Fig. 28.23: Inner surface of the right hip bone showing the  position of pudendal canal   Pudendal nerve is the chief nerve of the perineum  and of the external genitalia. It is accompanied by the  internal pudendal vessels.   Pudendal nerve arises from the sacral plexus in the  pelvis. It is derived from spinal nerves S2, S3, S4.   It originates in the pelvis, enters gluteal region through  greater sciatic notch, leaves it through lesser sciatic  notch to enter the pudendal canal in the lateral wall of  ischioanal fossa. It terminates by dividing into branches.   1 In the pelvis , the pudendal nerve descends in front of    2 Internal pudendal artery: This artery gives off the  inferior rectal artery in the posterior part of the  canal. In the anterior part of the canal, the artery  divides into the perineal artery and the artery of the piriformis deep to its fascia. It leaves the pelvis,  penis. Vein accompanies the artery. to enter the gluteal region, by passing through the   lower part of the greater sciatic foramen, between  the piriformis and the coccygeus, medial to internal  pudendal vessels.   2 In the gluteal region , the pudendal nerve crosses the  apex of the sacrospinous ligament, under cover of  gluteus maximus. Here it lies medial to the internal  pudendal vessels which cross the ischial spine.  Accompanying these vessels, the nerve leaves the  gluteal region by passing through the lesser sciatic  foramen, and enters the pudendal canal.   3 In the pudendal canal, the neurovascular bundle lies  in the lateral wall of the ischioanal fossa (Fig. 28.7).   In the posterior part of the pudendal canal the pudendal  nerve gives off the inferior rectal nerve, and then  divides into two terminal branches, the perineal nerve  and the dorsal nerve of the penis or clitoris (Figs 28.24  and 28.25).   The inferior rectal nerve pierces the medial wall of the  pudendal canal, crosses the ischioanal fossa from lateral    to medial side, and supplies the external anal sphincter,  the skin around the anus, and the lining of the anal  canal below the pectinate line (Fig. 28.9).   The perineal nerve is the larger terminal branch of the  pudendal nerve. It runs forwards below the internal  pudendal vessels, and terminates by dividing into:   b. Muscular branches to the urogenital muscles, and  to anterior parts of external anal sphincter and the  levator ani. The nerve to the bulbospongiosus also  gives off the nerve to bulb which supplies corpus  spongiosum, penis and the urethra.   The dorsal nerve of the penis or clitoris is the smaller  terminal branch of the pudendal nerve. It runs forwards  first in the pudendal canal above the internal pudendal  vessels; and then in the deep perineal space between  these vessels and the pubic arch. Next it passes through  the lateral part of the oval gap between the apex of the  perineal membrane and the arcuate pubic ligament,  runs on the dorsum of the penis or clitoris, and ends in  the glans penis or glans clitoridis. It supplies the skin  of the body of the penis or clitoris and of the glans.    The pudendal nerve supplies sensory branches to the  lower of the vagina, through the inferior rectal and  posterior labial branches. Therefore, in vaginal  operations, general anaesthesia can be replaced by a  pudendal nerve block. The nerve is infiltrated near the  ischial spine by a needle passed through the vaginal  wall and then guided by a finger (Fig. 28.26).   This is the chief artery of the perineum and of the  external genital organs. It is smaller in females than in  males.    Fig. 28.25: Course and distribution of the pudendal nerve, and of the internal pudendal artery   The artery is the smaller terminal branch of the anterior  division of the internal iliac artery, given off in the  pelvis; the larger branch is the inferior gluteal.    artery ends a little behind the arcuate pubic ligament  by dividing into the deep and dorsal arteries of penis  or of the clitoris (Fig. 28.25).   1 The inferior rectal artery arises near the posterior end  of the pudendal canal, and accompanies the nerve  of the same name. The artery supplies the skin,  muscles and mucous membrane of the anal region,  and anastomoses with the superior and middle rectal  arteries (Fig. 28.24).   2 The perineal artery arises near the anterior end of the  pudendal canal, and pierces the base of the perineal  membrane to reach the superficial perineal space.  Here it divides into the transverse perineal and the  posterior scrotal or posterior labial branches.   3 The artery of the penis or the clitoris runs in the deep  perineal space and gives off:   The course of internal pudendal artery is similar to  the course of pudendal nerve.   In the pelvis , the artery runs downwards in front of  the piriformis, the sacral plexus and the inferior gluteal  artery. It leaves the pelvis by piercing the parietal pelvic  fascia and passing through the greater sciatic foramen,  below the piriformis, thus entering the gluteal region.   In the gluteal region , the artery crosses the dorsal  aspect of the tip of the ischial spine, under cover of the  gluteus maximus. Here it lies between the pudendal  nerve medially and the nerve to the obturator internus  laterally. It leaves the gluteal region by passing through  the lesser sciatic foramen, and thus enters the pudendal  canal.   In the pudendal canal , the artery runs downwards and  forwards in the lateral wall of the ischioanal fossa, about  4 cm above the lower margin of the ischial tuberosity.  Here it is related to the dorsal nerve above and the  perineal nerve below. The artery gives off the inferior  rectal artery in the posterior part of the canal, and the  perineal artery in the anterior part. The internal  pudendal artery continues into the deep perineal space  as the artery of the penis or of the clitoris (Fig. 28.24).   In the deep perineal space , the artery of the penis or  clitoris which is continuation of internal pudendal  artery, runs forwards close to the side of pubic arch,  medial to the dorsal nerve of penis or of clitoris. The    All of them pierce the perineal membrane and reach  the superficial perineal space. The artery to the bulb  supplies the bulb of the penis or bulb of vestibule  and the posterior part of the urethra or only the  urethra. The urethral artery supplies the corpus  spongiosum and the anterior part of the urethra. The  deep artery of the penis or the clitoris traverses and  supplies the crus and the corpus cavernosum. The  dorsal artery of the penis or the clitoris supplies the skin  and fasciae of the body of the penis and of the glans  or the glans clitoridis.   The tributaries of internal pudendal vein follow the  branches of the internal pudendal artery. The vein  drains into internal iliac vein.   Penis consists of two corpora cavernosa containing the  deep artery of the penis and a single corpora  spongiosum with the urethra. All three erectile masses  contain spaces or caverns. The spaces are larger in  corpora cavernosa and smaller in corpus spongiosum.  These three corpora are covered by fasciae and skin. In  the deep fascia lie deep dorsal vein of penis, two dorsal  arteries and two dorsal nerves of penis. The superficial  dorsal vein of the penis lies in the superficial fascia.   Clitoris comprises two corpora cavernosa only.  Corpus spongiosum is absent. The two erectile masses  contain caverns or spaces.    • Perineum is divided into anterior by placed  urogenital triangle and posteriorly placed anal  triangle.   • Anal triangle comprises terminal part of anal canal  in the centre with right and left ischioanal fossae  on each side. Ischioanal fossa contains internal  pudendal vessels and pudendal nerve.   • Fat in ischioanal fossa keeps the anal canal closed  except at the time of defaecation.   • Sphincter urethrae is within the wall of urethra.  So there is hardly any deep perineal space.   • Perineal membrane is the key structure in  urogenital triangle. Main difference in male and  female perineum about the structures piercing the  perineal membrane is the additional vaginal  opening in female and two ducts of bulbourethral  glands in the male only.   • Key structure and central tendon of perineum is  perineal body.   • Body of clitoris in female is made up of only two  corpora cavernosa and no corpus spongiosum   • There is corpus spongiosum with urethra in the  penis of male in addition to two corpora cavernosa  (see Fig. 17.2).   • Clitoris is much smaller than the penis and is not  traversed by the urethra. Urethral orifice lies 2 cm  behind clitoris.   • Bulbspongiosus of two sides are separate in female  and overlie the bulb of vestibule. In male the two    are united by a median septum and overlie the bulb  of penis.   • Pudendal nerve supplies all the muscles and skin  of perineum.   • Inferior rectal nerve supplies mucous membrane  of the lower part of the anal canal, external anal  sphincter and the skin around anal opening.   • The labium majora contains sebaceous glands,  sweat glands and hair follicles.   • There are four openings in the vestibule one each,  of urethra, and vagina and two of ducts of  Bartholin's glands.    A woman few days after childbirth complained of a  painful swelling in her perianal region.   Ans: The fossa related to the anal region is the  ischioanal fossa. There is one fossa on each side of  the anal canal. The internal pudendal artery and  pudendal nerve in course through the pudendal  canal, lying in the lateral wall of the fossa.   The swelling occurred due to disruption of a small  branch of internal pudendal artery, probably as a  result of infection during childbirth or infection the  episiotomy area.   Ld 2. d 3, c 4. c 5. a 6. c   Pelvis is formed by articulation of each of the two hip  bones with the sacrum behind and with each other in  front. The greater pelvis is comfortably occupied by the  abdominal viscera, leaving only the lesser pelvis for the  pelvic viscera. Urinary bladder lies behind pubic  symphysis; rectum and anal canal are close to the  sacrum and coccyx. The middle space left is for the  genital organs. Many structures cross the brim of the  pelvis, i.e. curved line extending around the pelvis at the  junction of greater and lesser pelves (linea terminalis).   The bony pelvis is formed by four bones united at  four joints. The bones are the two hip bones in front  and on the sides, and the sacrum and coccyx behind.  The joints are the two sacroiliac joints, the pubic  symphysis and the sacrococcygeal joint.   The pelvis is divided by the plane of the pelvic inlet  or pelvic brim, or superior aperture of the pelvis into  two parts.   b. Lower part is known as the lesser or true pelvis.  The plane of the pelvic inlet passes from the sacral  promontory to the upper margin of the pubic  symphysis. The greater or false pelvis includes the  two iliac fossae, and forms a part of the posterior  abdominal wall. The lesser or true pelvis contains  the pelvic viscera.   The pelvic walls are made up of bones, ligaments and  muscles.   1 Anteriorly by the pubic symphysis and bodies of the  pubic bones.   3 On each side by the two rami of the pubis, the ischium  with its ramus, and the lower part of the ilium  (Fig. 29.1).   1 Obturator membrane closes the greater part of the  obturator foramen, and completes the lower part of  the lateral wall of the pelvis (Fig. 29.2).   2 S acrotuberous ligament and sacrospinous ligaments  bridge the gap between the hip bone and the sacrum,  and convert the greater and lesser sciatic notches into  the foramina of the same name (Fig. 29.3).   1 The obturator internus with its fascia reinforces the  lateral wall of the pelvis from the inside.   2 The piriformis with its fascia forms the posterior wall  of the pelvis. It also helps in filling the gap of the  greater sciatic foramen (Figs 29.4 and 29.5).   The pelvic inlet is an oblique plane, making an angle of   Fig. 29.2 : Bones and ligaments of pelvis seen from the front    Fig. 29.5: Muscles of the posterior part of the pelvic wall seen  from the front    posteriorly by the sacral promontory, anteriorly by the  upper margin of the pubic symphysis, and on each side  by the linea terminalis. The linea terminalis includes  the anterior margin of the ala of the sacrum, the arcuate  line or lower part of the medial border of the ilium, the  pectineal line of the pubis or pecten pubis, and the pubic  crest (Fig. 29.6).   The pelvic inlet is heart-shaped in the male , and is  widest in its posterior part. In the female, it is oval, and  is widest more anteriorly than in the male. Posteriorly,  the inlet is indented by the sacral promontory, more so  in the male than in the female (Fig. 29.7).   The pelvic outlet is bounded anteriorly by the arcuate or  inferior pubic ligament; posteriorly by the coccyx; and  on each side by the ischiopubic rami or side of the pubic  arch, the ischial tuberosities and the sacrotuberous    Fig. 29.3: Pelvic bones and ligaments seen from the medial side   Fig. 29.4: Muscles of the pelvic wall seen from the medial side    Fig. 29.6: Sagittal section of the pelvis showing the planes of  its inlet and outlet and their axes. The axis of the pelvic cavity is  J-shaped    Fig. 29.7: Shape of pelvic inlet in the male, and in the female    The muscles of the true pelvis, its blood vessels and  nerves are considered in Chapter 34.    ligaments. The posterior part of the outlet is formed by  the coccyx and the sacrotuberous ligaments. It is mobile  on the sacrum, and the sacrum itself is slightly mobile  at the sacroiliac joints (Fig. 29.6).   The pubic arch is formed by the ischiopubic rami of  the two sides and by the lower margin of the pubic  symphysis which is rounded off by the arcuate pubic  ligament (Fig. 29.2).    * The pelvis is a basin with its various walls and  many openings. The posterior wall contains  5 pairs of anterior sacral foramina. The greater and  lesser sciatic notches are converted into foramina  of the same name with the help of sacrotuberous  and sacrospinous ligaments. Greater sciatic  foramen is the "doorway" of the gluteal region.  Pudendal nerve enters the region through the  greater sciatic notch and quickly leaves it through  lesser sciatic notch to enter the perineum. The  lateral wall contains obturator foramen for the  passage of obturator nerve which supplies  adductors of the hip joint.   If fracture is at one point, the fracture will be stable.   * In athletes, anterior superior iliac spine may be  pulled off by forcible contraction of sartorius.  Similarly anterior inferior iliac spine or ischial  tuberosity may get avulsed by the contraction of  their attached muscles.   The pelvic floor is formed by the pelvic diaphragm  which consists of the levator ani and the coccygeus  (see Chapter 34). It resembles a hammock, or a gutter  because it slopes from either side towards the median  plane where it is traversed by the urethra and the anal  canal, and also by the vagina in the female. The pelvic  diaphragm separates the perineum below from the  pelvis above.    • Pelvic floor formed by two gutter-shaped levator  ani muscles supports the pelvic viscera, especially  during raised intra-abdominal pressure. The foetal  head travels in the axis of pelvic cavity (Fig. 29.8).  During second stage of labor, the head of the baby  on reaching the pelvic floor rotates from earlier  transverse position to the anteroposterior position.  The occiput moves downwards and forwards and  reaches below the 80°-85° angled pubic arch. Then  the head passes through the anterior hiatus of the  levator ani to reach the perineum and then deliver.  Sometimes episiotomy is given to enlarge the  perineum (Fig. 29.9).   • Injury to pelvic floor which mostly occurs during  vaginal delivery, may cause uterine, vaginal or  even rectal prolapse.   • Appendicitis occurring due to pelvic position of  the appendix may irritate the obturator nerve  leading to referred pain in the medial side of thigh  (see Fig. 20.23).   • Inflammation of ovaries may cause referred pain  in the medial side of thigh due to irritation of the  obturator nerve (see Fig. 31.1).   • The 2nd to 4th sacral nerves and coccygeal nerve  can be anaesthetised by the anaesthetic agent put  into the sacral canal. It is called caudal anaesthesia  and is used in obstetrics practice.   • Pain in the sacroiliac joint is felt on pressing the  posterior superior iliac spine present in a dimple  on the lower back (see Fig. 5.1).    Fig. 29.9: Head of the delivering baby seen at the perineum.  Site of episiotomy is also seen   The pelvic cavity is continuous above with the  abdominal cavity at the pelvic brim, and is limited  below by the pelvic diaphragm. The cavity is curved in  such a way that it is first directed downwards and  backwards, and then downwards and forwards  (J-shaped) as shown in (Fig. 29.10). It has unequal walls,  measuring only about 5 cm anteriorly and 15 cm  posteriorly. The cavity is more roomy or larger in the  female than in the male.   1 Sigmoid colon and rectum occupy the posterior part  of the pelvis.   2 Urinary bladder lies anteriorly. The prostate lies  below the neck of urinary bladder.   3 In between the bladder and rectum, there is a  transverse septum or genital septum made up of  connective tissue. In the male, the septum is small.  It contains the ductus deferens, the seminal vesicle  and the ureter on each side.   In the female, the septum is large, and contains the  uterus, the uterine tubes, the round ligament of the    Fig. 29.10: Side view of bony female pelvis. AA—Axis of pelvic  cavity (X-X—Plane of inlet, Y-Y—Zone of cavity, Z-Z— Plane of  outlet)   uterus, the ligaments of the ovary, ovaries, the vagina  and the ureters.   These contents are considered in detail in the  chapters that follow.   Fig. 29.11: Anterior (pelvic) view of the sacrum and attachment of sigmoid mesocolon    Fig. 29.12: Urachus and obliterated umbilical artery will cross the pelvic brim   11 Ductus deferens in male/round ligament of uterus  in female (see Fig. 32.2).    During childbirth, a woman was given pudendal  nerve block. She still complained of some pain during  her labour   • Which other nerves have to be anaesthetized to  get painless childbirth?   Ans: Pudendal nerve arises from ventral rami of S2,  S3, S4 segments of spinal cord. It is the nerve of the  perineum. It supplies three muscles of superficial  perineal space including most of the skin and mucous  membrane of perineum. So it is blocked by an  anaesthetic agent given above the ischial tuberosity.   Since sensations from perineum are also carried  by ilioinguinal (LI), genitofemoral (LI, L2), and  posterior cutaneous nerve of thigh, these nerves also  need to be blocked by making an injection of the same  agent along the lateral margin of labia majora.    • Axis of pelvic cavity is "J" shaped. Plane of outlet  of pelvis makes an angle of 15° with the horizontal  plane. Plane of inlet of pelvis makes an angle of  50°-60° with the horizontal plane.   • Shallowest wall of pelvis is its anterior wall.  Distance between two ischial spines is the least.    1. All the following are the characteristic features of  the female bony pelvis except:   5. All the following structures cross the brim of pelvis  in male except:   a. Internal iliac vessels b. Ovarian vessels  c. Iliolumbar artery d. Sympathetic trunks   Urinary bladder is the temporary store house of urine  which gets emptied through the urethra. The external  urethral sphincter is the sphincter urethrae which is  placed proximally in the wall of urethra, and not at the  terminal part of the urethra. In the case of pylorus and  anal canal, the sphincters are placed at their terminal  ends.   The male urethra subserving the functions of  urination and ejaculation, i.e. expulsion of semen is  18-20 cm long with curvatures and comprises  preprostatic, prostatic, membranous and longest  anterior bulbar and penile parts.   The female urethra is for urination only and is 4 cm  long. The cathetarisation if required is much easier in  the female than in the male.   Clean and define the muscles, membranes and  ligaments in the pelvic cavity. These are the levator ani  obturator internus muscles; medial and lateral pubo  prostatic ligaments and median, medial umbilical folds.   Identify the peritoneum on the superior surface of  the bladder situated just behind the pubic symphysis.  Identify and follow the median umbilical ligament from  the apex of bladder. Define the surfaces, blunt borders  and the openings in the urinary bladder.   In the male, trace the ductus deferens and ureter to  the base of the bladder on both sides. Pull the bladder  medially and identify the structures on its lateral surface,  e.g. the levator ani, obturator vessels and nerve,  superior vesical branch of umbilical artery and the  obliterated umbilical artery.   In female, the cervix and vagina lie behind the urinary  bladder.   Make the incision through the bladder wall along the  junction of the superior and inferolateral surface on both    sides. Extend these incisions till the lateral extremities  of the base. Incise the superior wall of the bladder to  be able to visualise its interior.   In the male, make a median section through the penis,  opening the entire length of the spongy part of the urethra.  Examine the internal structure of the urethra.   The urinary bladder is a muscular reservoir of urine,  which lies in the anterior part of the pelvic cavity. The  detrusor muscle of urinary bladder is arranged in  whorls and spirals and is adapted for mass contraction  rather than peristalsis.   The bladder varies in its size, shape and position  according to the amount of urine it contains.   When empty, it lies entirely within the pelvis; but as  it fills it expands and extends upwards into the  abdominal cavity, reaching up to the umbilicus or even  higher.   3 Neck, which is the lowest and most fixed part of the  bladder.   5 Four borders, two lateral, one anterior and one  posterior (Figs 30.1 and 30.2).   1 The apex is connected to the umbilicus by the median  umbilical ligament which represents the obliterated  embryonic urachus (Fig. 30.1).   a. In the female, it is related to the uterine cervix and  to the vagina (see Fig. 31.21).   b. In the male, the upper part of the base is separated  from the rectum by the rectovesical pouch (see  Fig. 18.17a) and the contained coils of intestine;  and the lower part is related to the seminal vesicles  and the terminations of the vas deferens (Fig. 30.3).  The triangular area between the two deferent  ducts is separated from the rectum by the  rectovesical fascia of Denonvilliers.   3 The neck is the lowest and most fixed part of the  bladder. It lies 3 to 4 cm behind the lower part of the  pubic symphysis, a little above the plane of the pelvic  outlet. It is pierced by the internal urethral orifice,  a. In males, smooth muscle bundles surround the   bladder neck and preprostatic urethra. These are  arranged as distinct circular collar with its own    Fig. 30.3: Posterior view of a male urinary bladder and its  relations to the genital ducts and glands    distinct adrenergic innervations. This is the  preprostatic sphincter and is devoid of  parasympathetic cholinergic nerves. It is part of  proximal urethral sphincter mechanism,  b. In females, neck is related to the pelvic fascia which  surrounds the upper part of the urethra.   In infants, the bladder lies at a higher level. The  internal urethral orifice lies at the level of the superior  border of the pubic symphysis. It gradually descends  to reach the adult position after puberty.   a. In males, it is completely covered by peritoneum,  and is in contact with the sigmoid colon and coils  of the terminal ileum (see Fig. 18.17a).   b. In females, peritoneum covers the greater part of  the superior surface, except for a small area near  the posterior border, which is related to the  supravaginal part of the uterine cervix. The  peritoneum from the superior surface is reflected  to the isthmus of the uterus to form the  vesicouterine pouch (see Fig. 18.17b).   5 Inferolateral surfaces: These are devoid of peritoneum,  and are separated from each other anteriorly by the  anterior border, and from the superior surface by the  lateral borders.   a. In the male, each surface is related to the pubis, the  puboprostatic ligaments, the retropubic fat, the  levator ani and the obturator internus (Fig. 30.4).   b. In the female, the relations are same, except that  the puboprostatic ligaments are replaced by the  pubovesical ligaments.   As the bladder fills, the inferolateral surfaces form  the anterior surface of the distended bladder, which is  covered by peritoneum only in its upper part. The lower  part comes into direct contact with the anterior  abdominal wall, there being no intervening peritoneum.  This part can be approached surgically without entering  the peritoneal cavity.   Fig. 30.4: Medial view of the lower part of the pelvic wall and  the pelvic diaphragm. The urinary bladder has been  superimposed to show relations of its inferolateral surface   These are condensations of pelvic fascia around the  neck and base of the bladder. They are continuous with  the fascia on the superior surface of the levator ani.   1 The lateral true ligament of the bladder extends from  the side of the bladder to the tendinous arch of the  pelvic fascia (Fig. 30.5).   2 The lateral puboprostatic ligament is directed medially  and backwards. It extends from the anterior end of  the tendinous arch of the pelvic fascia to the upper  part of the prostatic sheath ( see Fig. 32.8).   3 The medial puboprostatic ligament is directed  downwards and backwards. It extends from the back  of the pubic bone (near the pubic symphysis) to the  prostatic sheath. The ligaments of the two sides form  the floor of the retropubic space ( see Fig. 32.8).   In females, bands similar to the puboprostatic  ligaments are known as the pubovesical ligaments.  They end around the neck of the bladder (Fig. 30.5).   4 The median umbilical ligament is the remnant of the  urachus (Fig. 30.1).   5 The posterior ligament of the bladder is directed  backwards and upwards along the vesical plexus of  veins. It extends on each side from the base of bladder  to the wall of pelvis (Fig. 30.5).   These are peritoneal folds, which do not form any  support to the bladder. They include:   3 Lateral false ligament, formed by peritoneum of the  paravesical fossa.   4 Posterior false ligament formed by peritoneum of the  sacrogenital folds (see Fig. 18.20).   It can be examined by cystoscopy, at operation or at  autopsy.   In an empty bladder, the greater part of the mucosa  shows irregular folds due to its loose attachment to the  muscular coat.   In a small triangular area over the lower part of the  base of the bladder, the mucosa is smooth due to its  firm attachment to the muscular coat. This area is  known as the trigone of the bladder. The apex of the  trigone is directed downwards and forwards. The  internal urethral orifice, opening into the urethra is  located here. The ureters open at the posterolateral  angles of the trigone. Their openings are 2.5 cm apart  in the empty bladder, and 5 cm apart in a distended  bladder (Fig. 30.6).   A slight elevation on the trigone immediately  posterior to the urethral orifice produced by the median  lobe of the prostate, is called the uvula vesicae. The base  of the trigone is formed by the interureteric ridge or bar  of Mercier produced by the continuation of the inner  longitudinal muscle coats of the two ureters. The ridge    Fig. 30.6: Coronal section through the bladder and prostate to  show the interior of the bladder    extends beyond the ureteric openings as the ureteric folds  over the interstitial part of the ureters.    * The interior of the bladder can be examined in the  living by cystoscope (Fig. 30.7).   * A distended bladder may be ruptured by injuries  of the lower abdominal wall. The peritoneum may  or may not be involved.   * Chronic obstruction to the outflow of urine by an  enlarged prostate causes hypertrophy of bladder  leading to trabeculated bladder.   * In the operation of suprapubic cystotomy , the  bladder is distended with about 300 ml of fluid.  As a result the anterior aspect of the bladder comes  into direct contact with the anterior abdominal  wall, and can be approached without entering the  peritoneal cavity.   The mean capacity of the bladder in an adult male is  220 ml, varying from 120 to 320 ml. Filling beyond  220 ml causes a desire to micturate, and the bladder is  usually emptied when filled to about 250 to 300 ml.  Filling up to 500 ml may be tolerated, but beyond this  it becomes painful. Referred pain is felt in the lower  part of the anterior abdominal wall, perineum and penis  (Til to L2; S2 to S4).   1 The main supply comes from the superior and  inferior vesical arteries, branches of anterior trunk  of the internal iliac artery (see Fig. 34.1).   2 Additional supply is derived from the obturator, and  inferior gluteal arteries; and in females from the  uterine and vaginal arteries instead of inferior vesical.   Lying on the inferolateral surfaces of the bladder there  is a vesical venous plexus. Veins from this plexus pass  backwards in the posterior ligaments of the bladder,  and drain into the internal iliac veins.   Most of the lymphatics from the urinary bladder  terminate in the external iliac nodes. A few vessels may  pass to the internal iliac nodes or to the lateral aortic  nodes.   The urinary bladder is supplied by the vesical plexus  of nerves which is made up of fibres derived from  the inferior hypogastric plexus. The vesical plexus  contains both sympathetic and parasympathetic  components, each of which contains motor or efferent  and sensory or afferent fibres.   1 Parasympathetic efferent fibres or nervi erigentes, S2,  S3, S4 are motor to the detrusor muscle. These nerves  do not supply the preprostatic sphincter. If these are  destroyed, normal micturition is not possible.   2 Sympathetic efferent fibres (Til to L2) are said to be  inhibitory to the detrusor and motor to the  preprostatic sphincter mechanism.   3 The somatic, pudendal nerve (S2, S3, S4) supplies the  sphincter urethrae which is voluntary and is situated  within the wall of urethra.   4 Sensory nerves: Pain sensations, caused by distension  or spasm of the bladder wall, are carried mainly by  parasympathetic nerves and partly by sympathetic  nerves. In the spinal cord, pain arising in bladder  passes through the lateral spinothalamic tract , and  awareness of bladder distension is mediated through  the posterior columns. Bilateral anterolateral cordotomy ,  therefore, selectively abolishes pain without affecting  the awareness of bladder distension and the desire  to micturate.    • Emptying of bladder: Emptying of the bladder is  essentially a reflex function, involving the motor  and sensory pathways. Voluntary control over this  reflex is exerted through upper motor neurons,  and as long as one pyramidal tract is functioning  normally, control of the bladder remains normal.  Acute injury to the cervical/thoracic segments of  spinal cord leads to a state of spinal shock. The  muscle of the bladder is relaxed, the sphincter  vesicae contracted, but sphincter urethrae relaxed.  The bladder distends and urine dribbles.   After a few days, the bladder starts contracting  reflexly. When it is full, it contracts every 2-4 hours.  This is "automatic reflex bladder" (Fig, 30,8).   Damage to the sacral segments of spinal cord  situated in lower thoracic and lumbar one vertebra  results in "autonomous bladder". The bladder  wall is flaccid and its capacity is greatly increased.  It just fills to capacity and overflows. So there is  continuous dribbling (Fig, 30,9).   • Urinary bladder is one of sites for stone formation  as concentrated urine lies here.   Male urethra is 18-20 cm long that extends from the  internal urethral orifice in the urinary bladder to the  external opening (meatus) at the end of the penis.   1 Relatively short posterior urethra which is 4 cm  long, lies in the pelvis proximal to corpus spon¬  giosum and is acted upon by urogenital sphincter  mechanisms and also acts as a conduit.   Preprostatic part  Prostatic utricle  Prostatic and  membranous parts  of urethra  External urethral  sphincter (skeletal  muscle)    Fig. 30.10: Left view of a sagittal section through the male urethra  showing its subdivisions    2 Relatively long anterior urethra which is 16 cm long  within the perineum (proximally) and penis (distally).  It is surrounded by corpus spongiosum and is  functionally a conduit.   a. Bulbar urethral (proximal) component surrounded  by bulbospongiosus. Entirely within perineum  (Fig. 30.11).    Fig. 30.11: Anterior view of the male urethra straightened and  cut open   In flaccid penis, urethra as a whole represents  double curve except during the passage of fluid  along it. The urethral canal is a mere slit.   • The urethral slit is crescentic or transversely  arched in prostatic part (Fig. 30.12).   causes it to flow in a continuous stream. Since it is  passing under pressure, stream falls a little away from  the body. Males can urinate standing without wetting  themselves.   1-1.5 cm in length. It extends almost vertically from  bladder neck to verumontanum (superior aspect) in  prostatic urethra.   The preprostatic part is surrounded by proximal  urethral sphincter mechanism (Fig. 30.10).   Proximal urethral sphincter mechanism  In addition to the smooth muscle bundles which run in  continuity from the bladder neck down to the prostatic  urethra and distinct from the smooth muscle within the  prostate, smooth muscle bundles, surround the bladder  neck and preprostatic urethra. They are arranged as  distinct circular collar which has its own distinct  adrenergic innervations.   The bundles which form this preprostatic sphincter  are small in size compared with the muscle bundles of  detrusor and are separated by a relatively larger  connective tissue component rich in elastic fibres.   It is also different in that unlike detrusor and rest of  urethral smooth muscle (common to both sexes), the  preprostatic sphincter is almost totally devoid of  parasympathetic cholinergic nerves.   Contraction of preprostatic urethra serves to prevent  retrograde flow of ejaculate through proximal urethra  into bladder.   It may maintain continence when external sphincter  has been damaged. It is extensively disrupted in vast  majority of men with:   Simple mucus-secreting glands lie in the tissue  around the preprostatic urethra and surrounded by the  preprostatic sphincter. These simple glands are similar  to those in the female urethra and are unlike the glands  of prostate.   3—4 cm in length. It tunnels through the substance of  prostate closer to anterior than the posterior surface of  gland. Emerging from the prostate slightly anterior to  the apex (most inferior part), urethra turns inferiorly as  it passes through the prostate making an angle of 35°.   Throughout its length, the posterior wall has a  midline ridge called as urethral crest. This crest projects  into the lumen causing the lumen to appear crescentic  in transverse section.   On each side of crest are shallow depression called  prostatic sinus , the floor of which is perforated by orifices  of 15-20 ducts prostatic ducts.   There is an elevation called verumontanum (colliculus  seminalis) at about middle of urethral crest. It contains  slit-like orifice of prostatic utricle.   On both side of or just within this orifice are the two  small openings of the ejaculatory ducts (Fig. 30.11).   It is a cul-de-sac 6 mm long, which runs upwards and  backwards in the substance of prostate behind its  median lobe. The walls are composed of fibrous tissue,  muscle fibres and mucous membrane. The mucous  membrane is pitted by the openings of numerous small  glands. It develops from paramesonephric ducts or  urogenital sinus and is thought to be homologous with  the vagina of female.   So vagina masculine is also a name for this prostatic  utricle.   Lowermost part of prostatic urethra is fixed by  puboprostatic ligaments and is, therefore, immobile.   It is 1.5 cm, shortest, least dilatable and with the  exception of external orifice is the narrowest section of  urethra. Descends with a slight ventral concavity from  the prostate to bulb of penis, passing through the  perineal membrane. 2.5 cm posteroinferior to pubic  symphysis.   Wall of membranous urethra , i.e. part of external or distal  urethral sphincter mechanism   Its muscle coat is separated from epithelium by narrow  layer of fibroelastic connective tissue. Muscle coat  consists of relatively thin layer of bundles of smooth  muscle, which are continuous proximally with  those of prostatic urethra and a prominent outer layer  of the circularly oriented striated muscle fibres  (rhabdosphincter) which form external urethral  sphincter.   External sphincter represents points of highest in-  transurethral pressure in the normal, contracted state.   Intrinsic striated muscle is made of fibres of very  small diameter, devoid of muscle spindles,  physiologically being slow twitch type, unlike pelvic  floor with heterogenous mixture of slow and fast twitch  type of larger diameter. So slow twitch fibres of  sphincter are capable of sustained contraction over long  period of time and contribute to tone that closes the  urethra and maintains urinary continence.   b. Urethral striated muscle (of rhabdosphincter). It  is most important component as it is capable of  sustained contractions.   c. Pubourethral part of levator ani, important to resist  surges of intra-abdominal pressure (on coughing  or exercise).   Anterior or spongiosus part lies in corpus spongiosum  and is 16 cm long when penis is flaccid. It extends from  membranous urethra to external urethral orifice on  glans penis. It starts below the perineal membrane at a  point anterior to the lowest part of pubic symphysis  (Fig. 30.11).   Part of anterior urethra which is surrounded by  bulbospongiosus is called bulbar urethra and is wide part  of urethra. Bulbourethral glands open in this section  2.5 cm below the perineal membrane.   From here, when penis is flaccid, urethra curves  downwards as penile urethra. It is narrow and slit-like  when empty and has diameter of 6 mm when passing  urine. It is dilated at its termination within the glans  penis and dilatation is called "navicular fossa".   External urethral orifice is the narrowest part of urethra  and is a sagittal slit, 6 mm long, bounded on each side  by a small labium.   Epithelium of urethra, particularly in bulbar and  distal penile segment presents orifice of numerous small  glands and follicles situated in the submucous tissue  called urethral glands. It contains a number of small pit¬  like recesses, or lacunae of varying size whose orifice  are directed forwards.   One lacuna larger than the rest is lacuna magna which  is situated on the roof of navicular fossa.    Traumatic to urethra injured by a fall-astride (or  straddle) results in injury to penile urethra in the  perineum (see Fig. 28.15).   a. Posteriorly as the perineal membrane and the  membranous layer of superficial fascia are  continuous with the fascia around superficial  transverse perinei.   c. Above to lesser pelvis by intact perineal  membrane. So, extravasated urine goes anteriorly  into the loose connective tissue of scrotum and  penis and then to anterior abdominal wall.   1 Urethral artery arises from internal pudendal artery  just below perineal membrane and travels through  corpus spongiosum to reach glans penis.   Prostatic plexus supplies the smooth muscle of prostate  and prostatic urethra. Greater cavernous nerves are  sympathetic to preprostatic sphincter during  ejaculation. Parasympathetic nerves are from 2nd-4th  sacral segments.   Nerve supply of rhabdosphincter is controversial but  is said to be by neurons in Onufs nucleus situated in  sacral 2 segment of spinal cord fibres pass via perineal  branch of pudendal nerve.   Female urethra is only 4 cm long and 6 mm in diameter.  It begins at the internal urethral orifice of bladder,  approximately opposite middle of the pubic symphysis  and runs anteroinferiorly behind the symphysis pubis,  embedded in anterior wall of vagina. It crosses the  perineal membrane and ends at external urethral orifice  as an anteroposterior slit with rather prominent  margins situated directly anterior to the opening of  vagina and 2.5 cm behind glans clitoridis.   Except during passage of urine anterior and posterior  wall of canal possesses a ridge which is termed urethral  crest. Many small mucous urethral glands and minute  pit-like recess or lacunae open into urethra. On each  side, near the lower end of urethra, a number of these  glands are grouped and open into a duct, named  paraurethral duct.   Each paraurethral duct runs down in the submucous  tissue and ends in a small aperture on the lateral  margins of external urethral orifice.   Parasympathetic preganglionic fibres from 2nd-4th  sacral segments of spinal cord. These run through pelvic  splanchnic nerves and synapse in vesical venous plexus.  Postganglionic fibres reach smooth muscles.   Somatic fibres from same segments (S2-S4) reach the  striated muscles through pelvic splanchnic nerves that  do not synapse in vesical plexus.   Sensory fibres in pelvic splanchnic nerves reach to  2nd-4th sacral segments of spinal cord. Postganglionic  sympathetic fibres arise from plexus around the vaginal  arteries.   Wall has outer muscle coat and inner mucosa that lines  the lumen and is continuous with that of bladder.   Muscle coat: Outer sheath of striated muscle/external  urethral sphincter or distal sphincter mechanism  together with smooth muscle.   Female external urethral sphincter is anatomically  separate from the adjacent periurethral striated muscle  of the anterior pelvic floor, i.e. pubourethralis part of  levator ani.   The sphincter form a sleeve which is thickest  anteriorly in the middle one-third of urethra, and is  relatively deficient posteriorly. The striated muscle  extends into the anterior wall of both proximal and  distal thirds of urethra, but is deficient posteriorly.  Muscle cells forming external urethral sphincter are all  small diameter slow twitch fibres.   Smooth muscle coat (inner) extends throughout the  length of urethra. A few circularly arranged muscle  fibres occur in the outer aspect of nonstriated muscle  layer which are oblique or longitudinally oriented and  these intermingle with striated muscle fibres forming  inner parts of external urethral sphincter.   Proximally, the urethral smooth muscle extends  as far as the neck of bladder where it is replaced  by detrusor smooth muscle. But this region in the  females lacks well-defined circular smooth muscle  components comparable to the preprostatic sphincter  of male. Women do not possess an internal urethral  sphincter.   Distally, urethral smooth muscle terminate in  subcutaneous adipose tissue around external urethral  meatus.   Smooth muscle of female urethra receives an  extensive presumptive cholinergic nerve supply, but  few noradrenergic fibres.   In the absence of an anatomical sphincter,  competence of female bladder neck and proximal  urethra is unlikely to be totally dependent on smooth  muscle activity and is probably related to support  provided by ligamentous structures which surround  them.   Longitudinal orientation and the innervation of  muscles suggests that urethral smooth muscle in female  is active during micturition and serves to shorten and  widen urethral lumen.   1 Initially the bladder fills without much rise in the  intravesical pressure. This is due to adjustment of  bladder tone.   2 When the quantity of urine exceeds 220 cc, the  intravesical pressure rises. This stimulates sensory  nerves and produces a desire to micturate. If this is  neglected, rhythmic reflex contractions of the  detrusor muscle start, which become more and more  powerful as the quantity of urine increases. This  gives a feeling of fullness of the bladder, which later  on becomes painful. The voluntary holding of urine  is due to contraction of the sphincter urethrae and  of the perineal muscles, with coincident inhibition  of the detrusor muscle.   a. First there is relaxation of perineal muscles, except  the distal urethral sphincter and contraction of the  abdominal muscles.   b. This is followed by firm contraction of the detrusor  and relaxation of the proximal urethral sphincter  mechanism.   c. Lastly, distal urethral sphincter mechanism  relaxes, and the flow of urine begins.   4 The bladder is emptied by the contraction of the  detrusor muscle. Emptying is assisted by the  contraction of abdominal muscles.   5 When urination is complete, the detrusor muscle  relaxes, the proximal urethral sphincter mechanism  contracts, and finally the distal urethral sphincter  mechanism contracts. In the male, the last drops of  urine are expelled from the bulbar portion of the  urethra by contraction of the bulbospongiosus.   The epithelium of urinary bladder is of transitional  variety. The luminal cells are well-defined dome shaped  squamous cells with prominent nuclei. The middle    layers are pear-shaped cells and the basal layer is of  short columnar cells. The muscle coat is admixture of  longitudinal, circular and oblique layers. Outermost  layer is the serous or adventitial coat.   Cloaca (Latin sewer) is divided by the urorectal septum  into posterior anorectal canal and anterior primitive  urogenital sinus. The cranial and largest part of primitive  urogenital sinus called the vesicourethral canal forms  most of the urinary bladder. It is connected with the  allantois. The lumen of allantois gets obliterated to form  urachus connecting the apex of the bladder to the  umbilicus. This ligament is the median umbilical ligament.  Trigone of bladder is formed by the absorption of  mesonephric ducts and is mesodermal in origin. With  time, the mesodermal lining is replaced by endodermal  epithelium. So the epithelium is wholly endodermal,  while muscles are of splanchnic origin.   1 Vesicourethral canal formed by endoderm forms the  anterior wall of prostatic urethra above the opening  of prostatic utricle.   2 Absorbed portions of the mesonephric ducts, i.e.  mesoderm forms posterior wall of prostatic urethra  above the opening of prostatic utricle.   3 Definitive urogenital sinus formed by endoderm  forms the lower part of prostatic urethra and the  membranous urethra.   4 Urethral plate or endoderm forms most of the  anterior part of urethra.   5 Surface epithelium of glans penis or ectoderm forms  the terminal portion of penile urethra.    • Catheterization of bladder: In some cases, the patient  is unable to pass urine leading to retention  of urine. In such cases a rubber tube called a  catheter is passed into the bladder through the  urethra. While passing a catheter one has to  remember the normal curvatures of the urethra.  It has also to be remembered that the lacunae are  directed forwards, and may intercept the point  of the catheter (Fig. 30.13). Forceful insertion of  instruments may create false passages in the  urethra.   • Rupture of urethra: The urethra is commonly  ruptured beneath the pubis by a fall astride a  sharp object. This causes extravasation of urine  (see Figs 28.15 and 28.16).   • A constriction of the urethra is called stricture of  the urethra. It is usually a result of infection.   * Hypospadias is a common anomaly in which the  urethra opens on the undersurface of the penis or  in the perineum.   ■ Epispadias is a rare condition in which the urethra  opens on the dorsum of the penis. The condition  is associated with ectopia vesicae and absence of  infraumbilical part of anterior abdominal wall.    • Most fixed part of urinary bladder is the neck of  bladder.   • Least dilatable part of male urethra is the  membranous part. Narrowest part of urethra is  external urethral orifice.    A female patient about 50 years suffered injuries in  her pelvic region. X-ray showed fracture of pubic  bones and catheterized urine specimen showed the  presence of blood.   • Where would the extravasated urine go from the  ruptured urinary bladder?   Ans: The organ ruptured is the urinary bladder. The  pubic bones have also got fractured. As the bladder  has ruptured few blood vessels are injured, making  the urine red.   Urine would pass in the pelvic cavity and behind  ascending and descending colons into the paracolic  gutters. On percussion over descending colon, the  note would be dull. When the patient is rolled to right  side, urine escapes to right side and the note over  the descending colon gets resonant.   d. Awareness of distension of urinary bladder is  mediated by lateral spinothalamic tract    t\<i tttotnan catica// /tc tattytyteo ta/ta c/oci no/ attnt ant/ can/to/ /ntt /cf/y.  . \a woman ran m/t/naty/tcc tm/i/ i/tt can/ c/ioo.a cott iciotai/y ut/aJ/tttt t/tettti/4- at tat// no/ /e, a mo/Jtct   Female reproductive organs include external and  internal genital organs. The external genital organs have  been described in Chapter 28.   The internal genital organs comprise a pair of ovaries,  a pair of uterine/fallopian tubes, single uterus and  vagina. The ovaries are homologous to the testes of  males but lie within the pelvis. The ovaries are much  smaller than the testes.   Cut through the pubic symphysis with a knife in the  median plane and extend the incision into the urethra.  Make a median dorsal cut with a saw through the fourth  and fifth lumbar vertebrae, the sacrum and coccyx to  meet the knife. Cut through the soft tissues.   Separate the two halves of the pelvis and examine  the cut surface of all the tissues.   Locate the ovary on the lateral wall of pelvis in the  female cadaver. Identify the ovarian vessels in the  infundibulopelvic ligament and trace these to the ovary  and uterine tube. Follow, the ovarian artery till its  anastomosis with the uterine artery.   Identify the uterus and follow the peritoneum on its  superior and inferior surfaces which is thus free to move.  Trace the uterus downwards till the supravaginal part  of cervix which is attached to the lateral pelvic wall by  transverse cervical ligaments and to the sacrum by  uterosacral ligaments.   The vaginal part of cervix is surrounded on all sides  by fornices of the vagina. The posterior fornix is the  deepest. These can be felt by putting index and middle  fingers through the vagina.   Identify the broad ligament attaching uterus to the  lateral pelvic wall and note various structures present  in its borders and surfaces.   Each ovary lies in the ovarian fossa on the lateral pelvic  wall. The ovarian fossa is bounded:   2 Posteriorly by the ureter and the internal iliac artery  (Fig. 31.1).   The position of the ovary is variable. In nulliparous  women, its long axis is nearly vertical, so that the ovary  is usually described as having an upper pole and a  lower pole. However, in multiparous women, the long  axis becomes horizontal; so that the upper pole points  laterally and the lower pole medially (Figs 31.2a and b).   Fig. 31.1: Medial view of the boundaries of the ovarian fossa  as seen in a sagittal section    Figs 31.2a and b: Positions of the ovary, (a) It is vertical in  nullipara, and (b) horizontal in multipara (after one or more  deliveries) due to the pull by the pregnant uterus   In young girls, before the onset of ovulation , the ovaries  have smooth surfaces which are greyish pink in colour.  After puberty , the surface becomes uneven and the  colour changes from pink to grey.   Each ovary has two poles or extremities , the upper or  tubal pole, and the lower or uterine pole; two borders ,  the anterior or mesovarian border, and the posterior or  free border; and two surfaces , lateral and medial.   The ovary is almost entirely covered with peritoneum,  except along the mesovarian or anterior border where  the two layers of the covering peritoneum are reflected  on to the posterior layer of the broad ligament of the  uterus. The ovary is connected to the posterior layer of  the broad ligament by a short fold of peritoneum,  called the mesovarium (Fig. 31.3). The squamous  epithelium of the mesovarium is continuous with the  cubical epithelium of the ovary. The mesovarium  transmits the vessels and nerves to and from the ovary  (see Fig. 18.21).   The lateral part of the broad ligament of uterus,  extending from the infundibulum of the uterine tube  and the upper pole of the ovary, to the external iliac  vessels, forms a distinct fold known as suspensory  ligament of the ovary or infundibulopelvic ligament. It  contains the ovarian vessels and nerves (Fig. 31.4).    Fig. 31.3: Superior view of a horizontal section through the right  ovarian fossa and the lateral part of the broad ligament    Fig. 31.4: The subdivisions, relations and blood supply of the  uterine tube   1 Upper or tubal pole: It is broader than the lower pole,  and is related to the uterine tube and the external iliac  vein. The right ovary may be related to the appendix  if the latter is pelvic in position. The ovarian fimbria  and the suspensory ligament of the ovary are attached  to the upper pole of the ovary (Fig. 31.2).   2 Lower or uterine pole: It is narrower than the upper  pole and is related to the pelvic floor. It is connected,  by the ligament of the ovary, to the lateral angle of  the uterus, posteroinferior to the attachment of the  uterine tube. The ligament lies between the two  layers of the broad ligament of the uterus and  contains some smooth muscle fibres (Fig. 31.2).   3 Anterior or mesovarian border: It is straight and is  related to the uterine tube and the obliterated  umbilical artery. It is attached to the back of the broad   ligament of the uterus by the mesovarium, and forms  the hilus of the ovary (Fig. 31.3).   4 Posterior or free border: It is convex and is related to  the uterine tube and the ureter.   5 Lateral surface: It is related to the ovarian fossa which  is lined by parietal peritoneum. This peritoneum  separates the ovary from the obturator vessels and  nerve (Fig. 31.1).   6 Medial surface: It is largely covered by the uterine  tube. The peritoneal recess between the mesosalpinx  and this surface is known as the ovarian bursa.   Only the lower pole and lateral surfaces are not related to   utrine tube, remaining two borders , upper pole and medial  surface are related to the tube.   1 The ovarian artery arises from the abdominal aorta  fust below the renal artery. It descends over the  posterior abdominal wall and enters the suspensory  ligament of the ovary. It sends branches to the ovary  through the mesovarium, and continues medially  through the broad ligament of the uterus to  anastomose with the uterine artery (Fig. 31.4). In  addition to ovary, the ovarian artery also supplies  the uterine tube, the side of uterus and the ureter.   2 The uterine artery gives some branches which reach  the ovary through the mesovarium.   The veins emerge at the hilus and form a pampiniform  plexus around the artery. The plexus condenses into  a single ovarian vein near the pelvic inlet. This vein  ascends on the posterior abdominal wall and drains  into the inferior vena cava on the right side and into the  left renal vein on the left side.   The lymphatics from the ovary communicate with the  lymphatics from the uterine tube and fundus of the  uterus. They ascend along the ovarian vessels to drain  into the lateral aortic and preaortic nodes.   The ovarian plexus, derived from the renal, aortic and  hypogastric plexuses, accompanies the ovarian artery.  It contains both sympathetic and parasympathetic  nerves. Sympathetic nerves (T10, Til) are afferent for  pain as well as efferent or vasomotor. Parasympathetic  nerves (S2, S3, S4) are vasodilator.   1 Production of oocytes: During reproductive life of  about 30 years (from puberty to menopause), the  ovaries produce alternately one secondary oocyte per  month (per ovarian cycle of 28 days).    Liberation of oocyte from the ovary is called  ovulation. It occurs on or about the 14th day of the  28-day menstrual cycle. Variations in the length of  menstrual cycle are due to variations in the  preovulatory phase; the postovulatory phase is  constant.   An oocyte is viable (capable of being fertilized) for  about 12-24 hours.   Histologically, the ovary is made up of the following  parts from without inwards.   3 The cortex contains ovarian follicles at various stages  of development. Each follicle contains one oocyte.  One follicle matures every month and sheds an  oocyte. Total of 400 oocytes are ovulated in the  reproductive life. After the oocyte is liberated the  Graafian follicle is converted into a structure called  the corpus luteum.   4 The hormone oestrogen is secreted by follicular cells  of ovarian follicles. Another hormone, progesterone,  is produced by the corpus luteum.   5 Medulla has rich vascular connective tissue,  containing vessels, nerves and lymphatics.    * Determination of ovulation: In cases of sterility, the  ovulation can be determined by repeated  ultrasonography.   * Prolapse of ovaries: Ovaries are frequently displaced  to the pouch of Douglas where they can be  palpated by a PV or per vaginal examination.   * Ovarian cysts: The developmental arrest of the  ovarian follicles may result in the formation of one  or more small ovarian cysts.   Multiple small theca lutein cysts involve both the  ovaries in cases with Stein-Leventhal syndrome. The  syndrome is characterized by mild hirsutism, deep  voice, secondary amenorrhoea, and cystic  . enlargement of both the ovaries.   * Carcinoma of ovary is common, and accounts for 15%  of all cancers and 20% of gynaecological cancers.   * Ovaries are the commonest site in the abdomen  for endometriosis. The endometrial cysts in the  ovary are called the chocolate cysts.   They are tortuous ducts which convey oocyte from the  ovary to the uterus. Spermatozoa introduced into the  vagina pass up into the uterus, and from there into the  uterine tubes. Fertilization usually takes place in the  lateral part of the tube.   These are situated in the free upper margin of the broad  ligament of uterus.   Each uterine tube is about 10 cm long. At the lateral  end, the uterine tube opens into the peritoneal cavity  through its abdominal ostium . This ostium is about 3 mm  in diameter.   1 The lateral end of the uterine tube is shaped like a  funnel and is, therefore, called the infundibulum . It  bears a number of finger-like processes called fimbriae  and is, therefore, called the fimbriated end. One of the  fimbriae is longer than the others and is attached to  the tubal pole of the ovary. It is known as the ovarian  fimbria (Fig. 31.2).   2 The part of the uterine tube medial to the  infundibulum is called the ampulla. It is thin-walled,  dilated and tortuous, and forms approximately the  lateral two-thirds or 6 to 7 cm of the tube. It arches  over the upper pole of the ovary. The ampulla is  about 4 mm in diameter (Fig. 31.4). This is the site  for fertilisation.    3 The isthmus succeeds the ampulla. It is narrow,  rounded and cord-like. It forms approximately the  medial one-third or 2 to 3 cm of the tube.   4 The uterine or intramural or interstitial part of the tube  is about 1 cm long and lies within the wall of the  uterus. It opens at the superior angle of the uterine   , cavity by a narrow uterine ostium. This ostium is  about 1 mm in diameter.   1 The isthmus and the adjoining part of the ampulla  are directed posterolaterally in a horizontal plane.  Near the lateral pelvic wall, the ampulla arches over  the ovary and is related to its anterior and posterior  borders, its upper pole and its medial surface. The  infundibulum projects beyond the free margin of the  broad ligament.   2 The uterine tube lies in the upper free margin of the  broad ligament of the uterus. The part of the broad  ligament between the attachment of the mesovarium  and the uterine tube is known as the mesosalpinx  (Fig. 31.5). It contains the termination of the uterine  and ovarian vessels and the epoophoron.   The uterine artery supplies approximately the medial  two-thirds, and the ovarian artery supplies the lateral  one-third, of the tube. The veins run parallel with the  arteries and drain into the pampiniform plexus of the  ovary and into the uterine veins (Fig. 31.4).   Most of the tubal lymphatics join the lymphatics from  the ovary and drain with them into the lateral aortic and  preaortic nodes . The lymphatics from the isthmus  accompany the round ligament of the uterus and drain  into the superficial inguinal nodes.    Fig. 31.5: Posterosuperior view of the uterus and the right broad ligament   1 The sympathetic nerves from T10 to L2 segments are  derived from the hypogastric plexuses. They contain  both visceral afferent and efferent fibres. The latter are  vasomotor and perhaps stimulate tubal peristalsis.  However, peristalsis is mainly under hormonal control.   2 Parasympathetic nerves are derived from the vagus for  the lateral half of the tube and from the pelvic  splanchnic nerves from S2, S3, S4 segments of spinal  cord for the medial half. They inhibit peristalsis and  produce vasodilatation.   2 The middle muscular coat , which is thick in the  isthmus and thin in the ampulla. The circular muscle  coat is thickest in the isthmus and acts as a sphincter  which delays the progress of the zygote towards the  uterus until it is sufficiently mature for implantation.   3 The inner mucous membrane , which is lined by the  ciliated columnar epithelium mixed with the non-  ciliated secretory cells or peg cells. The mucous  membrane is thrown into complicated folds which fill  up the lumen of the tube. In the isthmus, there are  only 3-6 primary folds and the cilia tend to disappear.  But in the ampulla, the folds are more complex and  exhibit the secondary and even tertiary folds.    • Salpingitis: Inflammation of the uterine tube is  called salpingitis (Salpinx=trumpet or tube).   • Sterility: Inability to have a child is called sterility.  The most common cause of sterility in the female  is tubal blockage which may be congenital, or  caused by infection. Patency of the tube can be  investigated by:   a. Insufflation test or Rubin's test . Normally, air  pushed into the uterus passes through the tubes  and leaks into the peritoneal cavity. This  leakage produces a hissing or bubbling sound  which can be auscultated over the iliac fossae.   b. Hysterosalpingography is a radiological technique  by which the cavity of the uterus and the lumina  of the tubes can be visualized, after injecting a  radiopaque oily dye into the uterus (Fig. 31.6).   • Tubal pregnancy : Sometimes the fertilized ovum  instead of reaching the uterus adheres to the walls  of the uterine tube and starts developing there.  This is known as tubal pregnancy. The enlarging  embryo may lead to rupture of tube.    * Tubectomy: For purposes of family planning a  woman can be sterilized by removing a segment  of the uterine tube on both sides. This can be done  by laparoscopy (Fig. 31.7) or through an incision  in abdominal wall (Fig. 31.8).   * Transport of ovum: The transport of ovum is chiefly  due to muscular contractions. The ciliary move¬  ments create an effective stream of lymph towards  the uterus which assists in the nourishment of ovum  in the lumen of the tube over the mucosal ridges.   In layman's language, the uterus is called the womb. It  is also called hystera, on which word hysterectomy is  based.   Uterus is a child-bearing organ in females, situated in  the pelvis between bladder and rectum. Though hollow,  it is thick walled and firm, and can be palpated  bimanually during a PV (per vaginal) examination.   It is the organ which protects and provides nutrition  to a fertilized ovum, enabling it to grow into a fully  formed foetus. At the time of childbirth or parturition  contractions of muscle in the wall of the organ result in  expulsion of the foetus from the uterus.   The uterus is pyriform in shape. It is about 7.5 cm long,  5 cm broad, and 2.5 cm thick. It weighs 30 to 40 grams.  It is divisible into an upper expanded part called the  body and a lower cylindrical part called the cervix . The  junction of these two parts is marked by a circular  constriction called the isthmus. Part of uterus above  the opening of fallopian tube is called the fundus. The  body forms the upper two-thirds of the organ, and the  cervix forms the lower one-third.   The superolateral angle of the body project outwards  at the junction of body and fundus and is called cornua  of uterus. The uterine tube, ligament of ovary and round  ligament are attached to it on each side.   Normally, the long axis of the uterus forms an angle of  about 90 degrees with the long axis of the vagina. The  angle is open forwards. The forward bending of the  uterus relative to the vagina is called anteversion. The  backward bending of the uterus relative to vagina is  known as retroversion. The uterus is also slightly flexed  at the level of internal os of cervix; this is referred to as  anteflexion. The angle of anteflexion is 125 degrees  (Figs 31.9a to c).   Roughly, the long axis of the uterus corresponds to  the axis of the pelvic inlet, and the axis of the vagina to  the axis of the pelvic cavity and of the pelvic outlet (see  Fig. 29.6).   It is normally deviated to right side and is called  dextrorotation.   Superiorly, the uterus communicates on each side  with the uterine tube, and interiorly, with the vagina  (Fig. 31.5).   The fundus is formed by the free upper end of the  uterus. Fundus lies above the openings of the uterine  tubes. It is convex like a dome. It is covered with  peritoneum and is directed forward when the bladder  is empty. The fertilized oocyte is usually implanted in  the posterior wall of the fundus (Fig. 31.5).   The anterior or vesical surface of the body is flat and  related to the urinary bladder. It is covered with  peritoneum and forms the posterior or superior wall  of the uterovesical pouch.   The posterior or intestinal surface is convex and is  related to coils of the terminal ileum and to the sigmoid  colon. It is covered with peritoneum and forms the  anterior wall of the rectouterine pouch (see Figs 18.17b  and 18.21).   Each lateral border is rounded and convex. It provides  attachment to the broad ligament of the uterus which  connects it to the lateral pelvic wall. The uterine tube  opens into the uterus at the upper end of this border.  This end of the border gives attachment to the round  ligament of the uterus, anteroinferior to the tube; and  to the ligament of the ovary posteroinferior to the tube.  The uterine artery ascends along the lateral border of  the uterus between the two layers of the broad ligament  (Figs 31.10 and 31.11). ^   In sagittal section, the cavity of the body of the uterus  is seen as a mere slit because the uterus is compressed  anteroposteriorly. In coronal section, the cavity is seen  to be triangular in shape, the apex being directed  downwards. At the apex, the cavity becomes  continuous with the canal of the cervix. The junction is  called the internal os. The superolateral angles of the  cavity receive the openings of the right and left uterine  tubes (Fig. 31.5).   The cervix is the lower, cylindrical part of the uterus. It  is less mobile than the body. It is about 2.5 cm long,  and is slightly wider in the middle than at either end.  The lower part of the cervix projects into the anterior  wall of the vagina which divides it into supravaginal  and vaginal parts.   b. Posteriorly to the rectouterine pouch, containing  coils of intestine and to the rectum (see Fig. 18.17b).   c. On each side, to the ureter and to the uterine  artery, embedded in parametrium. The fibrofatty    Figs 31.9a to c: (a) Angulations of the uterus and vagina, and their axes, (b) angle of anteversion, and (c) angle of anteflexion    Fig. 31.10: Uterus, vagina and urinary bladder seen from the left side after removing the left broad ligament    tissue between the two layers of the broad  ligament and below it, is called the parametrium .  It is most abundant near the cervix and vagina  (Fig. 31.10).   The vaginal part of the cervix projects into the anterior  wall of the vagina. The spaces between it and the  vaginal wall are called the vaginal fornices. The cervical    canal opens into the vagina by an opening called the  external os. In a nulliparous woman, i.e. a woman who  has not borne children, the external os is small and  circular (Fig. 31.5). However, in multiparous women,  the external os is bounded by anterior and posterior  lips, both of which are in contact with the posterior wall  of the vagina.   The cervical canal, i.e. the cavity of the cervix is  fusiform in shape. It communicates above with the  cavity of the body of the uterus, through the internal os,  and below with the vaginal cavity through the external  os. The canal is flattened from before backwards so that  it comes to have anterior and posterior walls. These  walls show mucosal folds which resemble the branches  of a tree called the arbor vitae uteri . The folds in the  anterior and posterior walls interlock with each other  and close the canal.   These are mere peritoneal folds which do not provide  any support to the uterus.   1 The anterior ligament consists of the uterovesical fold  of peritoneum.   2 The posterior ligament consists of the rectovaginal fold  of peritoneum ( see Fig. 18.17).   3 The right and left broad ligaments are folds of  peritoneum which attach the uterus to the lateral  pelvic wall. When the bladder is full, the ligament  has anterior and posterior surfaces, and upper, lower,  medial and lateral borders. The upper border is free.  The anterior and posterior layers of peritoneum  forming the ligament become continuous here. The  lateral and inferior borders of the ligament are  attached to the corresponding parts of the pelvic  wall. The medial border is attached to the lateral  margin of the uterus (see Fig. 18.21).   The ovary is attached to the posterior layer of the  broad ligament through the mesovarium (Fig. 31.3). The  ligament of the ovary passes from the lower pole of the  ovary to the lateral angle of the uterus. The part of the  broad ligament lying between the uterine tube and the  ligament of ovary is called the mesosalpinx, while the  part below the ligament of ovary is called the  mesometrium. The part of the broad ligament that  stretches from the upper pole of the ovary and the  infundibulum of the uterine tube to the lateral pelvic  wall is called the suspensory ligament of the ovary or the  infundibulopelvic ligament (Fig. 31.5).   4 Uterine vessels near its attachment to the uterus  (Fig. 31.4).   10 Dense connective tissue or parametrium present  on the sides of the uterus.   These are described separately under the heading of  "supports" of uterus.   1 Chiefly by the two uterine arteries which are  markedly enlarged during pregnancy.   The uterine artery is a branch of the anterior division  of the internal iliac artery. It first runs medially towards  the cervix, crossing the ureter above the lateral fornix  of the vagina and 2 cm lateral to the cervix. Then the  artery ascends along the side of the uterus, with a  tortuous course. Finally, it runs laterally towards the  hilus of the ovary, and ends by anastomosing with the  ovarian artery. The tortuosity of the artery without  stretching the artery permits expansion of the uterus  during pregnancy (Fig. 31.12). Apart from the uterus,  the artery also gives branches to without stretching the  artery.   The veins form a plexus along the lateral border of the  uterus. The plexus drains through the uterine, ovarian  and vaginal veins into the internal iliac veins.   Lymphatics of the uterus begin at three intercommuni¬  cating networks, endometrial, myometrial and  subperitoneal. These plexuses drain into lymphatics on  the side of the uterus. Of these, the upper lymphatics from  the fundus and upper part of the body drain mainly  into the aortic nodes, and only partly to the superficial  inguinal nodes along the round ligament of the uterus.  The lower lymphatics from the cervix drain into the  external iliac, internal iliac and sacral nodes. The middle  lymphatics from the lower part of body drain into the  external iliac nodes (Fig. 31.13).    Pain sensation from the body of the uterus pass along  the sympathetic nerves, and from the cervix, along the  parasympathetic nerves.   1 In foetal life: The cervix is larger than the body which  projects a little above the pelvic brim.   2 At puberty: The uterus enlarges and descends to the  adult position. The arbor vitae uteri also appear.   3 During menstruation: The uterus is slightly enlarged  and becomes more vascular. The lips of the external  os are swollen.   4 During pregnancy: The uterus is enormously  enlarged, mainly due to hypertrophy of the smooth  muscle fibres and partly due to hyperplasia. As  pregnancy advances the uterine wall becomes  progressively thinner. After parturition the uterus  gradually involutes and returns almost to the  nonpregnant size.   5 In old age: The uterus becomes atrophic and smaller  in size and more dense in texture. The internal os is  frequently obliterated. The lips of the external os  disappear, and the os itself may be obliterated.   The uterus is a mobile organ which undergoes extensive  changes in size and shape during the reproductive  period of life. It is supported and prevented from  sagging down by a number of factors which are chiefly  muscular and fibromuscular.    The uterus is richly supplied by both sympathetic and  parasympathetic nerves, through the inferior  hypogastric and ovarian plexuses. Sympathetic nerves  from T12, LI segments of spinal cord produce uterine  contraction and vasoconstriction. The parasympathetic  nerves (S2, S3, S4) produce uterine inhibition and  vasodilatation. However, these effects are complicated  by the pronounced effects of hormones on the genital  tract.   These are of doubtful value and are formed by  peritoneal ligaments.   3 Rectovaginal or rectouterine pouch and fold of  peritoneum (see Fig. 18.17b).   The pelvic diaphragm (Fig. 31.14) supports the pelvic  viscera and resists any rise in the intra-abdominal   pressure. The pubococcygeus part of the levator ani is  partly inserted into the perineal body between the  vagina and the rectum. Some of these fibres also form  a supporting sling and a sphincter for the vagina, and  so indirectly for the uterus and the urinary bladder. If  the pubococcygeus is torn during parturition, the  support to the vagina is lost, and the latter tends to  sink into the vestibule along with the uterus, thus  causing prolapse of the uterus. The efficacy of the levator  ani as a support is also lost when the perineal muscles  are torn. They normally fix the perineal body, and make  it an anchor for the levator ani (Fig. 31.14).    Fig. 31.14: Superior view of the pelvic diaphragm (the levator  ani and coccygeus)   It is a fibromuscular node to which ten muscles are  attached. It acts as an anchor for the pelvic diaphragm,  and thus maintains the integrity of the pelvic floor. The  muscles are two superficial transversus perinei two  deep transversus perinei, two pubococcygeus part of  levator ani, two bulbospongiosus and single sphincter  ani externus and unstriped fibres of longitudinal muscle  coat of the anal canal (see Fig. 28.4).   The urogenital diaphragm does not exist as sphincter  urethrae is within the wall of the urethra. The urethral  sphincter mechanism exists. In addition there is  compressor urethrae and sphincter urethrae vaginalis.  Since these are inserted into vagina, they support the  uterus indirectly (see Fig. 28.20).    Fig. 31.15: Anteversion of the uterus is maintained by the couple  of forces provided by the pull of the uterosacral ligament and  the round ligament of the uterus   maintained by the uterosacral and round ligaments  (Figs 31.9 and 31.15).   These ligaments connect the cervix to the posterior  surface of pubis. They are derived from the endopelvic  fascia, and correspond to the medial and lateral  puboprostatic ligaments in the male (Fig. 31.16a).   These are also known by various other names like lateral  cervical ligaments; cardinal ligaments; paracervical  ligaments; retinacula uterine sustentaculum of Bonny  (Figs 31.16b and 31.17).   These are fan shaped condensations of the  endopelvic fascia on each side of the cervix above the  levator ani and around the uterine vessels. They connect  the lateral aspects of the cervix and of the upper vaginal  wall to the lateral pelvic wall, about 2.5 cm ventral to  the ischial spine. They form a 'hammock' that supports  the uterus.   These are also condensations of the endopelvic fascia.  They connect the cervix to the periosteum of the sacrum  (S2, S3) and are enclosed within rectouterine folds of  peritoneum (which form the lateral boundaries of the  rectouterine pouch). The uterosacral ligaments keep the  cervix braced backwards against the forward pull of  the round ligaments. The two ligaments form a couple  that maintains the uterine axis (Figs 31.16a and 31.18).   The anteverted position of the uterus itself prevents the  organ from sagging down through the vagina. Any rise  in intra-abdominal pressure tends to push the uterus  against the bladder and pubic symphysis, which further  accentuates anteversion. The angle of anteversion is   The round ligaments are two fibromuscular flat bands,  10 to 12 cm long, which lie between the two layers of  the broad ligament, anteroinferior to the uterine tube.  Each ligament begins at the lateral angle of the uterus,  runs forwards and laterally, passes through the deep   Figs 31.16a and b: Condensation of pelvic fascia forming the supports of the pelvic organs, (a) Superior view of the ligamentous  supports of the uterus and rectum, (b) coronal view of the right cardinal ligament   inguinal ring, traverses the inguinal canal and merges  with the areolar tissue of the labium majus after  breaking up into thin filaments. In the inguinal canal,  it is accompanied by a process of peritoneum during  foetal life. If it persists after birth, it is known in females  as the canal of Nuck. The round ligament keeps the  fundus pulled forwards and maintains the angle of   anteversion against the backward pull of the uterosacral  ligaments (Figs 31.10, 31.11 and 31.15).   The mucous membrane is called the endometrium,  which undergoes cyclic changes in three phases in one  menstrual cycle. There is no submucous coat.   Myometrium is thickest layer made of an outer and  an inner longitudinal coats and middle thick circular  coat with lots of arterioles.   1 Proliferative phase: The lining comprises simple  columnar epithelium. Stroma contains simple  tubular glands. Its deeper part contains sections  of coiled arteries.   2 Progestational phase: The glands get sacculated and  tortuous. The sections of coiled arteries are seen  in the superficial part of thick endometrium.   3 Menstrual phase: This phase occurs due to decline  of both the hormones. The endometrium becomes  ischaemic and starts being shed. The vessel wall  gets necrosed and blood enters the stroma and  menstrual flow starts.    • Colpotomy and colporrhaphy: Posterior colpotomy is  done to drain the pus from the pouch of Douglas.   • Intrauterine contraceptive device is used to prevent  implantation of fertilised oocyte (Fig. 31.19).   * Uterus is common site of formation of fibroids  (Fig. 31.20).   * Perineal body is one of the chief supports of pelvic  organs. Damage to the perineal body often leads  to prolapse of the uterus and of other pelvic organs.   The vagina is a fibromuscular canal, forming the female  copulatory organ. The term Vagina' means a sheath.   The vagina extends from the vulva to the uterus, and is  situated behind the bladder and the urethra, and in  front of the rectum and anal canal.   In the erect posture, the vagina is directed upwards and  backwards. Long axis of uterus and cervix forms an angle  of 90° with long axis of vagina (Figs 31.9b and 31.21).   The anterior wall of the vagina is about 8 cm long and  the posterior wall about 10 cm long.    The diameter of the vagina gradually increases from  below upwards. The upper end or vault is roughly  5 cm twice the size of the lower end (2.5 cm). However,  it is quite distensible and allows passage of the head of  the foetus during delivery (Figs 31.5 and 31.10).   The lumen is circular at the upper end because of the  protrusion of the cervix into it. Below the cervix, the  anterior and posterior walls are in contact with each  other, so that the lumen is a transverse slit in the middle  part, and is H-shaped in the lower part.   In the virgin, the lower end of the vagina is partially  closed by a thin annular fold of mucous membrane  called the hymen . In married women the hymen is  represented by rounded elevations around the vaginal  orifice, the caruncular hymenales.   The interior of the upper end of the vagina or vaginal  vault is in the form of a circular groove that surrounds  the protruding cervix. The groove becomes  progressively deeper from before backwards and is  arbitrarily divided into four parts called the vaginal  fornices. The anterior fornix lies in front of the cervix  and is shallowest. The posterior fornix lies behind the  cervix and is deepest. The lateral fornices lie one on each  side of the cervix (Figs 31.5 and 31.9).   1 Upper half is related to the base of the bladder.   1 Upper one-fourth is separated from the rectum by  the rectouterine pouch.   2 Middle two-fourths are separated from the rectum  by loose connective tissue.   3 Lower one-fourth is separated from the anal canal  by the perineal body and the muscles attached to it.   1 Upper one-third is related to the transverse cervical  ligament of pelvic fascia in which are embedded a  network of vaginal veins, and the ureter gets crossed  by the uterine artery (Fig. 31.22).   2 Middle one-third is related to the pubococcygeus  part of the levator ani.   3 Lower one-third pierces the perineal membrane,  below which it is related to the bulb of the vestibule,  the bulbospongiosus and the duct of greater  vestibular gland of Bartholin (see Figs 28.19, 31.22  and 31.23).    Branches of these arteries anastomose to form  anterior and posterior midline vessels called the vaginal  azygos arteries.   The rich vaginal venous plexus drains into the internal  iliac veins through the vaginal veins which accompany  the vaginal arteries.   Lymphatics from the upper one-third of the vagina  drain into the external iliac nodes; from the middle one-  third into the internal iliac nodes; and from the lower  one-third into the medial group of superficial inguinal  nodes.    The vagina is a very vascular organ, and is supplied by  the following arteries.   1 The main artery supplying it is the vaginal branch  of the internal iliac artery.   2 In addition, the upper part is supplied by the  cervicovaginal branch of the uterine artery  (Fig. 31.23). The lower part is by the middle rectal  and internal pudendal arteries.    Fig. 31.22: Vagina and some related structures as seen in  coronal section    Fig. 31.23: Arterial supply of vagina and uterus by the uterine  artery   1 The lower one-third of the vagina is pain sensitive  and is supplied by the pudendal nerve through the  inferior rectal and posterior labial branches of the  perineal nerve.   2 The upper two-thirds of the vagina are pain  insensitive and are supplied by sympathetic LI, L2  and parasympathetic segments S2 to S4. Nerves are  derived from the inferior hypogastric and  uterovaginal plexuses. Sympathetic nerves are  vasoconstrictor and parasympathetic nerves  vasodilator. The fibres which accompany the vaginal  arteries form the vaginal nerves.   As ureter lies anterior to internal iliac artery and  immediately behind ovary it forms the posterior  boundary of the ovarian fossa. It descends down till  ischial spine. Then it courses anteromedially towards  urinary bladder (Fig. 31.1).   In its anteromedial part, ureter is related to the  uterine artery, cervix and vaginal fornices. Ureter lies  in endopelvic fascia in inferomedial part of broad  ligament of uterus, where it may be damaged  (Figs 31.10, 31.12 and 31.23).   In the broad ligament, uterine artery is antero-  superior to ureter by 2.5 cm and then crosses the ureter  to ascend along lateral side of the uterus (Fig. 31.5).   Ureter runs forwards slightly above the lateral fornix  of vagina and is 2 cm lateral to supravaginal part of  cervix. It then turns medially towards urinary bladder  and is apposed to vagina.   Left ureter to often more close to vagina, as uterus is  slightly on the right side and vagina is on the left side  of median plane.   One has to be careful of ureter, especially during  ligation of the uterine artery. Ureter exhibits peristaltic  movements and can be identified easily.   3 Muscle coat consists of an outer longitudinal and an  inner circular layer.   4 The outer fibrous coat is the usual connective tissue.  There are no glands in the vaginal mucosa. It is kept   moist by the cervical glands from above and the greater  vestibular glands from below. The vaginal fluid is acidic  in nature because of the fermentation of glycogen (in  vaginal cells) by the Doderlein's bacilli.   a, Inspection: Vagina is first inspected at the  introitus by separating the labia minora with  the left hand. Next the speculum examination  is done to inspect the cervix and vaginal vault,  and to take the vaginal swab.   b. Palpation of the pelvic organs can be done by a  per vaginal (PV) digital examination (Fig. 31.24).  With the examining fingers one can feel:   - Laterally , the ovary, tube, lateral pelvic wall,  thickened ligaments, and ureters; and   Bimanual (abdominovaginal) examination helps  in the assessment of the size and position of the  uterus, enlargements of the ovaries and tubes, and  the other pelvic masses.   • Vaginal lacerations: Traumatic lacerations of vagina  are common, and may be caused by forcible coitus  (rape), during childbirth, or by accidents. This may  give rise to profuse bleeding.   • Vaginitis: It is common before puberty and after  menopause because of the thin delicate  epithelium. In adults, the resistant squamous  epithelium prevents the infection. Vaginitis is  commonly caused by the trichomonas, monilial  and gonococcal infections. It causes leucorrhoea  or white discharge.   • Prolapse: Prolapse of the anterior wall of vagina  drags the bladder (cystocoele) and urethra  (urethrocoele); the posterior wall drags the rectum  (rectocoele).   Weakness of supports of uterus can give rise to  different degrees of prolapse.    Similarly, trauma to the anterior and posterior  walls of vagina can cause the vesicovaginal,  urethrovaginal and rectovaginal fistulae.   • Neoplasms: Primary new growths of vagina, like  the infections, are uncommon. However,  secondary involvement of vagina by the cancer  cervix is very common.   * Episiotomy is an incision given in posterolateral  side of vagina to increase the size of outlet for the  baby during delivery. The position of episiotomy  incision during 2nd stage of labor is shown (see  Fig. 29.9). Some muscles of superficial perineal  space are incised.   Sex of the embryo is determined at the time of  fertilization.   The chromosomal complement in female is 'XX'.  Various components of ovary are germs cells, follicular  cells and the stromal cells.   Germ cells get migrated from the dorsocaudal end  of the yolk sac. Follicular cells are derived from the  epithelial cells of the coelomic epithelium, while stromal  cells are derived from mesoderm.   There is no tunica albuginea in the ovary and the  cortical part of the gonad predominates.   Ovary descends down till the pelvis. Its descent is  interrupted due to the presence of the single uterus,  which divides the gubernaculum into ligament of ovary  and round ligament of uterus.   In female, mullerian or paramesonephric duct  predominates. This duct is situated lateral to  mesonephric duct. It opens caudally into definitive  urogenital sinus. Mullerian duct proliferates due to  presence of oestrogens and absence of testosterone and  of mullerian inhibiting substance. Mullerian duct forms  all four parts of fallopian tube. The distal part of the  two ducts fuse to form the single uteroyaginal canal  which gives rise to uterus with its funduVbody and  cervix parts.   Wolffian duct or mesonephric duct forms the trigone  of urinary bladder as functional component. Duct of  Gartner is its vestigial component (Table 31.1).   These only form vestigial elements in female. These  are epoophoron, paroophoron and aberrant ductules.   It consists of 10 to 15 parallel tubules situated in the  lateral part of the mesosalpinx between the ovary and  the uterine tube. The tubules end in a longitudinal duct.  These tubules represent cranial mesonephric tubules  while the duct is a remnant of the mesonephric duct  (Fig. 31.5).   It consists of a few very short rudimentary tubules  situated in the broad ligament between the ovary and  uterus. These represent caudal mesonephric tubules  which are not attached to the mesonephric duct.   Occasionally, the duct of the epoophoron is much larger  than usual and is called the duct of Gartner. It can be  traced first along the uterine tube, and then along the  lateral margin of the uterus up to the level of the internal  os. Further down it runs through the cervix and the  lateral wall of the vagina, and ends near the free margin  of the hymen. It represents the mesonephric duct. It  may form a cyst in the anterior or lateral wall of the  vagina.    Table 31.1: Comparison between the derivatives of female and male urogenital structures   Testis descends outside the abdominal cavity as  spermatogenesis requires 3 degree lower temperature   Occasionally, one or two pedunculated cysts are found  attached to the fimbriated end of the uterine tube. These  are called the vesicular appendices or paramesonephric  appendices. These are believed to develop from the  cranial end of the paramesonephric duct.   As the fused miillerian or paramesonephric ducts which  form the uterovaginal canal open into the definitive  urogenital sinus, the endoderm bulges to form the  miillerian tubercle. Uterovaginal canal forms upper  l /3rd of vagina.   Endoderm on either side of miillerian tubercle  proliferates to form two sinovaginal bulbs which fuse  to form vaginal plate. The vaginal plate surrounds the  caudal end of the uterovaginal canal.   Soon there is canalisation of the vaginal plate to form  lower 2/3rd of vagina and vaginal fornices. It opens  through an endodermal partial septum—the hymen in  the definitive urogenital sinus.   Mesenchymal cells migrate around cloacal membrane  to form cloacal folds. These folds fuse ventrally to form  genital tubercle.   Cloacal folds get divided into urethral folds  anteriorly and anal folds posteriorly. This occurs at the  same time that the cloacal membrane gets divided into  urogenital membrane and anal membrane.   Lateral to urethral folds another pair of folds, the  genital swellings, make their appearance.   Genital tubercle forms clitoris; urethral folds form labia  minora, genital swellings form labia majora, urogenital  membrane gets ruptured to form the vestibule.   Rectum: Middle rectal, inferior rectal (inferior rectal  is the branch of pudendal)   * Main ligamentous support of uterus is the  transverse cervical ligament.    * Site of implantation of the blastocyst is posterior  wall of fundus of uterus, close to its body.   * Uterine artery crosses ureter from lateral to medial  side anteriorly to run tortuously along lateral  surface of uterus.   * The epithelium of uterus is simple columnar type.  The glands are simple, tubular. The submucous  layer is absent. Tall columnar cells line the cervical  canal.   * The cortex of the ovary is full of follicles. The  medulla contains hilus cells, homologous to the  interstitial cells of the testis.   * Pelvic part of the ureter about 13 cm long, lies close  to the supravaginal part of the cervix. It is narrow  at (i) where ureter crosses the brim of pelvis, (ii)  where it is crossed by the uterine artery and (iii)  in the intravesical part.   * Broad ligament has four parts: (i) infundibulo-  pelvic ligament, (ii) mesovarium, (iii) mesosalpinx  and (iv) mesometrium.   * Round ligament is 10-12 cm long with one end  attached to uterine cornua and other to anterior  third of labia majora.   * Forced penetration of penis into vagina is known  as "rape". It is a punishable crime.   * Caesarean section is the delivery of the baby by  cutting open the anterior abdominal wall and the  uterus.    Due to repeated child births, a female felt something  out at the perineum, especially while standing.   Ans: The organ which descends down is the uterus.  It occurs due to repeated childbirths. Normally the  organ is supported by number of muscles and  ligaments. These may get weakened and stretched  and thus are unable to support uterus. So uterus  descends down through vagina. Its supports are:   Muscular: All parts of levator ani, perineal body  with its attached muscles and distal urethral  sphincter mechanism.   3. Which of the following is not a content of broad  ligament?   The male reproductive organs include the external and  internal genitalia. The external genitalia are the penis  and the scrotum containing testis, epididymis and part  of ductus deferens. The internal genitalia on each side  are, the part of ductus deferens, the seminal vesicle,  the ejaculatory ducts, and the prostate.   The external genitalia have been described in  Chapter 17, and the male urethra in Chapter 30. The  remaining structures are considered below.   The ductus deferens has been seen till the deep inguinal  ring in the anterior abdominal wall. Follow it from there  as it hooks round the lateral side of inferior epigastric  artery to pass backwards and medially across the  external iliac vessels to enter into the lesser pelvis.  There it crosses the ureter and lies on the posterior  surface of urinary bladder medial to the seminal vesicle  (Fig. 32.2). Separate the ductus from the adjacent  seminal vesicle and trace these till the base of the  prostate gland (refer to #).   Follow the deep dorsal vein of the penis and its two  divisions into the prostatic venous plexus situated in  the angle between the bladder and the prostate.   Feel the thickened puboprostatic ligaments. Feel the  firm prostate lying just at the neck of the urinary bladder.   Identify the levator prostatae muscle lying  inferolateral to the prostate. This is identifiable by pulling  both the bladder and prostate medially. The first part  of urethra traverses the prostate. Cut through the  anterior one-third of the gland to expose the prostatic  urethra.   The ductus deferens is also called the vas deferens or the  deferent duct.   The ductus deferens is a thick-walled, muscular tube  which transmits spermatozoa from the epididymis to  the ejaculatory duct (Fig. 32.1). It feels cord-like at the  upper lateral part of scrotum. Ductus deferens has a  narrow lumen except at the terminal dilated part called  the ampulla (Fig. 32.2).   1 Within the scrotum along the posterior border of the  testis.   2 In the inguinal canal as part of the spermatic cord  (Fig. 32.1).   1 The ductus deferens begins as a continuation of the  tail of the epididymis (Fig. 32.1).   2 Along the posterior border of the testis: At first it is very  tortuous, but gradually straightens as it ascends  along the posterior border of the testis, medial to the  epididymis.   3 In the spermatic cord: The ductus deferens lies vertically  in posterior part of spermatic cord. It runs upwards  to the superficial inguinal ring, and then traverses the    Fig. 32.1: Schematic diagram to show the relationship of the  ductus deferens to the testis and the spermatic cord   inguinal canal. In the vertical part of its course, it can  be felt as a cord-like structure within the spermatic  cord.   4 In the greater pelvis: At the deep inguinal ring it leaves  the spermatic cord, and hooks round the lateral side  of the inferior epigastric artery. It then passes  backwards and medially, across fhe external iliac  vessels, and enters the lesser pelvis (Fig. 32.2).   5 In the lesser pelvis: The ductus deferens runs  downwards and backwards on the lateral pelvic wall,  deep to the peritoneum. Here it crosses the  obliterated umbilical artery, the obturator nerve and  vessels, and the vesical vessels. It then crosses the  ureter, and bends medially at right angles, to enter  the sacrogenital fold of peritoneum. Reaching the  base of the urinary bladder the ductus runs  downwards and forwards medial to the seminal  vesicle. Here it approaches the opposite duct and  reaches the base of the prostate (Fig. 32.3).   At the base of the prostate, the ductus deferens is  joined at an acute angle by the duct of the seminal  vesicle to form the ejaculatory duct.    Fig. 32.3: Prostate gland and some related structures as seen  in sagittal section    The part of the ductus lying behind the base of the  bladder, is dilated and tortuous, and is known as the  ampulla (see Fig. 30.3).   The artery to the ductus deferens arises from one of  the terminal branches of the superior vesical artery. It  accompanies the ductus to testis, where it anastomoses  with the testicular artery.   Veins from the ductus join the vesical venous plexus  which opens into the internal iliac vein.   The lining epithelium of vas deferens is of pseudo-  stratified ciliated type. The underlying lamina propria  contains elastic fibres. The muscle coat is in three layers,  middle is circular and outer and inner layers are of  longitudinal type. Adventitia is made of thin connective  tissue layer with fine nerves and arterioles.    Fig. 32.2: Schematic diagram to show the course of the ductus  deferens    * Vasectomy or removing part of the vas deferens is  one of the commonest operations being done for  purposes of family planning. It is a minor  operation which is done under local anaesthesia.  A median incision is made in the upper part of  the scrotum, just below the penis. Through this  incision both the deferent ducts are operated. A  short segment of each duct is excised, and the cut  ends are ligated. The operation is reversible, and  recanalisation can be done if required (Fig. 32.4).   * After vasectomy, the testes continue to produce  the hormones normally to maintain the male   characteristics. The hormones pass out through  the veins. Sperms are present in the ejaculations  after vasectomy for 2-3 months as it is an emptying  process. Newly formed sperms are destroyed in  the epididymis and are removed by phagocytosis.    symphysis and the upper part of the pubic arch. It lies  in front of the ampulla of the rectum (Figs 32.3 and 32.5).   It resembles an inverted cone, measuring about 4 cm  transversely at the base, i.e. width; 3 cm vertically, i.e.  length; and 2 cm anteroposteriorly or thickness. It  weighs about 8 g.   The prostate presents an apex directed downwards; a  base; four surfaces: anterior, posterior and two  inferolateral.   These are two lobulated sacs, situated between the  bladder and rectum. Each vesicle is about 5 cm long,  and is directed upwards and laterally. The lower  narrow end forms the duct of the seminal vesicle which  joins the ductus deferens to form the ejaculatory duct  (see Fig. 30.3).   The seminal vesicles do not form a reservoir for  spermatozoa. Their secretion forms a large part of the  seminal fluid. The secretion is slightly alkaline and  contains fructose and a coagulating enzyme called the  vesiculase.   The prostate is an accessory gland of the male repro¬  ductive system. The secretions of this gland add bulk  to the seminal fluid along with those of the seminal  vesicles and the bulbourethral glands. The prostate is  firm in consistency. Its firmness is due to the presence  of a dense fibromuscular stroma in which the glandular  elements are embedded. In the female the prostate is  represented by the paraurethral glands of Skene.   The apex is directed downwards surrounds the junction  of prostatic and membranous parts of posterior urethra.  It is separated from the anal canal by the perineal body  (Fig. 32.3).   The base is directed upwards, and is structurally  continuous with the neck of the bladder. The junction  is marked by a circular groove which lodges venules  of the vesical and prostatic plexuses.   The anterior surface is narrow and convex from side to  side. It lies 2 cm behind the pubic symphysis, with  retropubic fat intervening. Its upper part is connected  to the pubic bones by the puboprostatic ligaments. The  lower end of this surface is pierced by the urethra. The  lower end of urethra emerges from this surface  anterosuperior to the apex of gland. This surface is  composed of fibrous tissue.   The posterior surface is triangular in shape. It is  flattened from side to side and convex from above  downwards. It is separated from the rectum by the  fascia of Denonvilliers which is the obliterated  rectovesical pouch of peritoneum. Near its upper border    The prostate lies in the lesser pelvis, below the neck of  the urinary bladder, behind the lower part of the pubic   it is pierced on each side of the median plane by the  ejaculatory duct. This surface lies 4 cm from the anus,  and can be easily palpated on digital examination  through the rectum (Fig. 32.3).   The inferolateral surfaces are related to the side walls  of pelvis. The anterior fibres of the levator ani enclose  the gland in pubourethral sling. They are separated  from the muscle by a plexus of veins embedded in its  sheath (Fig. 32.5).   1' The peripheral zone forms 70% of glandular tissue.  It is situated posteriorly and is cancer vulnerable  (Fig. 32.6).   2 Central zone constitutes 25% of glandular tissue  situated posterior to urethral lumen and above the  ejaculatory ducts. The two zones are like^n egg in  its egg-cup. The central zone is not involved in  disease and is of Wolfian duct origin.   3 There is a periurethral transition zone (5%) from  which benign prostatic hyperplasia arises. The  central zone and transition zone constitute "central  gland".   In the preprostatic part of urethra there is proximal  urethral sphincter mechanism that subserves sexual  function of closing during ejaculation. If this sphincter  gets resected, retrograde ejaculation occurs (Fig. 32.7).   Distal urethral sphincter mechanism is seen at the  junction of prostatic and membranous parts of urethra.  It is horseshoe shaped, with most of the bulk lying  anteriorly. It is distinct from muscle of pelvic floor.    median and two lateral. These were one anterior, one  posterior, one median and two lateral. As of now, the  glandular tissue is divided into three lobes, two lateral  and one median (Figs 32.7a to c).   It is formed by condensation of the peripheral part of  the gland. It is fibromuscular in structure and is  continuous with stroma of the gland. The lies between  true and false capsules venous plexus (Fig. 32.8).   It lies outside the true capsule and is derived from the  endopelvic fascia. Anteriorly , it is continuous with the  puboprostatic ligaments. On each side, the prostatic  venous plexus is embedded in between false and true  capsules. Posteriorly , it is avascular, and is formed by  the rectovesical fascia of Denonvilliers (Fig. 32.3).   A pair of medial puboprostatic and a pair of lateral  puboprostatic ligaments extend from the false capsule  to the back of pubic bone. The medial pair lie near the  apex while lateral pair is close to the base. These four  ligaments support the gland.   1 Prostatic urethra traverses the gland vertically at the  junction of its anterior one-third with the posterior  two-thirds (Figs 32.7a and b).   2 The prostatic utricle is a blind sac directed upwards  and backwards. It opens at the middle of the urethral  crest.   3 The ejaculatory ducts pass downwards and forwards,  and open into the prostatic urethra on each side of  the opening of the prostatic utricle (Figs 32.7a to c).   The prostate gland was described as having five lobes  initially. These were one anterior, one posterior, one    Histological sections of the prostate do not show the  lobar pattern of the organ. Instead there are two well-  defined concentric zones separated by an ill-defined  irregular capsule. The zones are absent anteriorly  (Fig. 32.9).   The outer larger zone is composed of large branched  glands, the ducts of which curve backwards and open  mainly into the prostatic sinuses. This zone is frequently  the site of carcinoma.   The inner smaller zone is composed of submucosal  glands opening in the prostatic sinuses, and a group of  short, simple mucosal glands surrounding the upper  part of the urethra. These zones are typically prone to  benign hypertrophy.   The prostate is supplied by branches from the inferior  vesical, middle rectal and internal pudendal arteries.   Figs 32.7a to c: Lobes of the prostate gland as seen in sections through different planes, (a) Left view of a sagittal section, (b) posterior  half of a coronal section, and (c) horizontal section. The prostatic utricle, ejaculatory duct and the prostatic urethra are also seen    Branches of these arteries form a large outer or  subcapsular plexus, and a small inner or periurethral  plexus. The greater part of the gland is supplied by the  subcapsular plexus.   The veins form a rich plexus around the sides and  base of the gland. The plexus communicates with the  vesical plexus and with the internal pudendal vein, and  drains into the vesical and internal iliac veins. Valveless  communications exist between the prostatic and  vertebral venous plexuses through which prostatic  carcinoma can spread to the vertebral column and to  the skull (Fig. 32.10).    Fig. 32.8: Ligaments and venous plexus of prostate gland Lymphatic Drainage    Fig. 32.9: Horizontal section through the prostate gland showing  the histological zones and the glands in them    Lymphatics from the prostate drain chiefly into the  internal iliac and sacral nodes; and partly into the  external iliac nodes.   The prostatic plexus of nerves is derived from the lower  part of the inferior hypogastric plexus. It contains thick  nerves and numerous large ganglia. In addition to the  prostate and structures within it, the plexus also  supplies the seminal vesicles, the corpora cavernosa,  the corpus spongiosum, the membranous and penile  parts of the urethra, and the bulbourethral glands.   The prostate is supplied by both sympathetic and  parasympathetic nerves. The gland contains numerous  end-organs, impulses from which are relayed to the    lower three lumbar and upper sacral segments.  Secretions of the prostate are produced and discharged  after stimulation of both the parasympathetic and  sympathetic nerves.   1 At birth the prostate is small in size, and is made up  mainly of stroma in which a simple duct system is  embedded. During the first 6 weeks after birth the  epithelium of the ducts and of the prostatic utricle  undergoes hyperplasia and squamous metaplasia,  under the stimulation of maternal oestrogens.  Thereafter, up to the age of 9 years changes are  negligible. Between 9 and 14 years, the duct system  becomes more elaborate by formation of side buds,  and the gland slowly increases in size.   2 At puberty the male hormones bring about  rapid changes in the gland. In about one year it  becomes double its prepubertal size due to rapid  growth of the follicles and condensation and  reduction of the stroma.   3 From 20 to 30 years there occurs marked proliferation  of the glandular elements with infolding of the  glandular epithelium into the lumen of the follicles,  making them irregular.   4 From 30 to 45 years the size of the prostate remains  constant, and involution starts. The epithelial  infoldings gradually disappear and amyloid bodies  increase in number.   5 After 45 to 50 years the prostate is either enlarged  called the benign hypertrophy or reduced in size  called the senile atrophy.   Prostate is a fibromuscular glandular organ. The stroma  comprises collagen fibres and smooth fibres. The    columnar epithelium of acini is folded. The lumen may  contain small colloid masses called amyloid bodies. The  prostatic urethra, lined by transitional epithelium may  also be seen.   Prostate develops from a series of endodermal buds from  the lining of primitive urethra and the adjacent portion  of urogenital sinus, during first 3 months of intrauterine  life. The surrounding mesenchyme condenses to form  the stroma of the gland. Prostatic utricle develops in  the region of mullerian tubercle similar to vagina in  females. The central zone of glandular tissue is of  wolffian duct system.    • Senile enlargement of prostate: After 50 years of age  the prostate is often enlarged due to benign  hypertrophy or due to the formation of an  adenoma. This causes retention of urine due to  distortion of the urethra. Enlargement of the  median lobe not only projects into bladder, but  forms a sort of valve over the internal urethral  orifice, so that more patient strains, more it  obstructs the passage. Urine passes when the  patient relaxes.   Digital examination of the rectum is very  helpful in the diagnosis of an enlarged prostate  (Fig. 32.11). Removal of such a prostate called  prostatectomy relieves the urinary obstruction.  During removal, the enlarged gland is enucleated,  leaving behind both the capsules and venous  plexus between them.   The prostate can be removed through bladder  (transvesical), through prostatic capsule  (retropubic), or through perineum and fascia of  Denonvilliers (perineal approach) or through  urethra (TUR: transurethral resection).   • Inflammation of the prostate is referred to as  prostatitis. It may be acute or chronic. Acute  prostatitis is secondary to gonococcal urethritis  and chronic prostatitis may be secondary to  tuberculous infection of epididymis, seminal  vesicles and the bladder.   • Different zones of the prostate gland are seen in  Fig. 32.6.   • Benign prostatic hyperplasia occurs in  periurethral zone. Carcinoma of prostate occurs  in peripheral zone (Fig. 32.12).   • The prostate is a common site of carcinoma. It  usually occurs after the age of 50-55 years. In  addition to urinary obstruction, it causes pain in  perineum, low backache or sciatica. Rectal  examination reveals an irregular hard and fixed   prostate. Metastatic spread occurs to the vertebral  column through the valveless connections  between the prostatic and vertebral venous  plexuses (Fig. 32.10).    1 Epidural plexus lies in vertebral canal outside the dura  mater. The plexus consists of a postcentral and a  prelaminar portion. Each portion is drained by two  vessels. It drains the structures in the vertebral canal,  and is itself drained at regular intervals by segmental  veins (vertebral, posterior intercostal, lumbar and  lateral sacral).   2 Plexus within the vertebral bodies: It drains backwards  into the epidural plexus, and anterolaterally into the  external vertebral plexus.   3 External vertebral venous plexus: It consists of anterior  vessels in front of the vertebral bodies, and the  posterior vessels on the back of vertebral arches and  adjacent muscles. It is drained by segmental veins.  Suboccipital plexus of veins is a part of the external   plexus. It lies on and in the suboccipital triangle. It  receives the occipital veins of scalp, is connected with  the transverse sinus by emissary veins, and drains into  the subclavian veins.   2 Below with the pelvic veins, portal vein, and caval  system of veins.   The veins are valveless and the blood can flow in  them in either direction. An increase in intrathoracic  or intra-abdominal pressure, such as is brought about  by coughing and straining, may cause blood to flow in  the plexus away from the heart, either upwards or  downwards. Such periodic changes in venous pressure  are clinically important because they spread tumours  or infections. Thus the cells from pelvic, abdominal,  thoracic and breast tumours may enter the venous  system, and may ultimately lodge in the vertebrae, the  spinal cord, skull, or brain.   The common primary sites causing secondaries in  vertebrae are the breast, prostate, and kidney. Vertebral  tuberculosis is similarly explained.   1 Carcinoma of prostate causing secondaries in the  vertebral column and the skull.   Vertebral venous system is made up of a valveless,  complicated network of veins with a longitudinal  pattern. It runs parallel to and anastomoses with the  superior and inferior venae cavae. This network has  three intercommunicating subdivisions (Fig. 32.10).    Prostate comprises three lobes, one median, one  anterior, one posterior and two lateral.   Benign hypertrophy of prostate occurs in the  median lobe; carcinoma occurs in the peripheral  zone of prostate.   Per-rectal examination is an important examination  to judge the prostate, or anal canal pathology.  Prostatic adenoma is enucleated, both the capsules  are left behind in the patient.   Cancer of prostate may metastasise to distant parts  through vertebral venous plexus.   A 65-year-old man had prostatectomy done 2 years  back. Because of low backache he got X-ray of spine  done which showed secondaries in the lumbar  vertebrae   Ans: The cancer cells pass via venous system.  Prostatic venous plexus drains into internal iliac  veins and also into vertebral venous plexus through  ventral sacral foramina. These pass up along this  plexus situated in the epidural space till lumbar  vertebrae causing secondaries there.   These cancer cells can also travel up through this  quiet, valveless dangerous venous plexus in the  cervical region and to basilar venous plexus inside  the cranial cavity. Thus cancer of prostate Can spread  till the cranial cavity.   A man was referred for vasectomy. A few problems  were posed to the medical student.   Ans: Vasectomy is done on both sides at the same  sitting, one after the other.   Vas deferens is palpated as a firm muscular tube  in the spermatic cord.   Tire vas is pulled out from the incision at the upper  posterior part of scrotum and ligated at two places  one cm apart. The intervening part is removed and  sent for histopathological examination to confirm  that the tissue removed is vas deferens only.   3. Mesonephric duct in male forms all the following  structures except:    The lowest part of the gastrointestinal tract is formed  by the rectum and anal canal. Useful components of  the food are absorbed and waste material is expelled  from the anus; which is the external opening of the anal  canal seen in the perineum. Anal canal is heavily  guarded by the sphincters and is subjected to many  maladies. Balanced food at proper timing decreases  these maladies.   Identify the relation of the peritoneum to the upper two-  thirds of the rectum. See the structures/viscera related  to the rectum both in male and female cadavers. Cut  through the rectum and examine its mucous membrane  with a hand lens.   Find the superior rectal artery, as the continuation of  the inferior mesenteric artery. Trace it on to the posterior  surface of the upper part of rectum and follow its  branches downwards on the posterolateral surfaces till  the lowest part of the rectum. Trace the middle rectal  artery from its origin from the internal iliac artery till the  wall of the rectum.   The rectum is the distal part of the large gut. It is placed  between the sigmoid colon above and the anal canal  below. Distension of the rectum causes the desire to  defaecate.   The rectum in man is not straight as the name implies.  In fact it is curved in an anteroposterior direction and  also from side to side. The three cardinal,features of  the large intestine, e.g. sacculations, appendices  epiploicae and taeniae are absent in the rectum.    The rectum is situated in the posterior part of the lesser  pelvis, in front of the lower three pieces of the sacrum  and the coccyx (Fig. 33.1).   The rectum begins as a continuation of the sigmoid colon  at the level of third sacral vertebra. The rectosigmoid  junction is indicated by the lower end of the sigmoid  mesocolon. The rectum ends by becoming continuous  with the anal canal at the anorectal junction. The junction  lies 2 to 3 cm in front of and a little below the tip of the  coccyx. In males the junction corresponds to the apex of  the prostate.   The rectum is 12 cm long. In the upper part it has the  same diameter of 4 cm as that of the sigmoid colon, but  in the lower part it is dilated to form the rectal ampulla .    Fig. 33.1: Sagittal section through the male pelvis showing the  location of the rectum and some of its anterior and posterior  relations   In its course, the rectum runs first downwards and  backwards, then downwards, and finally downwards  and forwards (Fig. 33.1).   The beginning and the end of the rectum lie in the  median plane, but it shows two types of curvatures in  its course.   a. The sacral flexure of the rectum follows the  concavity of the sacrum and coccyx.   b. The perineal flexure of the rectum is the backward  bend at the anorectal junction (Figs 33.2a and b).   a. The upper lateral curve of rectum is convex to the  right.   b. The middle lateral curve is convex to the left and  is most prominent.   1 The upper one-third of the rectum is covered with  peritoneum in front and on the sides.    Figs 33.2a and b: Curvatures of the rectum: (a) Anteroposterior  curves, and (b) side to side (lateral) curves   3 The lower one-third, which is dilated to form the  ampulla, is devoid of peritoneum, and lies below the  rectovesical pouch in males and below the  rectouterine pouch in females. The distance between  the anus and the floor of the pouch is 7.5 cm in males  but only 5.5 cm in females (Figs 33.3a and b).   1 The upper two-thirds of the rectum are related to  the rectovesical pouch with coils of intestine and  sigmoid colon.   2 The lower one-third of the rectum is related to the  base of the urinary bladder, the terminal parts of the  ureters, the seminal vesicles, the deferent ducts and  the prostate (see Fig. 30.3).   1 The upper two-thirds of the rectum are related to  the rectouterine pouch with coils of intestine and  sigmoid colon. The pouch separates the rectum from  the uterus, and from the upper part of the vagina.   2 The lower one-third of the rectum is related to the  lower part of the vagina ( see Figs 18.17b and 31.21).   The relations are the same in the male and female. They   1 Lower three pieces of the sacrum, the coccyx and the  anococcygeal ligament.   3 The median sacral, the superior rectal and the lower  lateral sacral vessels.   4 The sympathetic chain with the ganglion impar; the  anterior primary rami of S3, S4, S5, coccygeal 1 and  the pelvic splanchnic nerves; lymph nodes,  lymphatics and fat (Fig. 33.4).    Fig. 33.4: Posterior relations of the rectum (below the level of the middle of the third piece of the sacrum)   The mucous membrane of an empty rectum shows two  types of folds, longitudinal and transverse.   The longitudinal folds are transitory. They are present  in the lower part of an empty rectum, and are  obliterated by distension.   The transverse or horizontal folds or Houston's valves  or plicae transversales are permanent and most marked  when the rectum is distended.   a. The first small transverse fold projects from right  wall. It is 12-14 cm above anal canal.   b. The second transverse fold lies near the upper end  of the rectum, and projects from the left wall    situated 7.5 cm above anus. Sometimes it may  encircle and partially constrict the lumen.   c. The third transverse fold , the largest and most  constant, lies at the upper end of the rectal  ampulla, and projects from the anterior and right  walls. It is some above anus.   d. Th e fourth transverse fold which is inconstant lies  2.5 cm below the middle fold, and projects from  the left wall (Figs 33.5a and b).   The rectum has two developmental parts. The upper  part related to the peritoneum develops from the   hindgut and lies above the third transverse fold of the  rectum. The lower part devoid of peritoneum develops  from the cloaca and lies below the third transverse fold.   Functionally, the sigmoid colon is the faecal reservoir  and the whole of the rectum is empty in normal  individuals, being sensitive to distension. Passage of  faeces into the rectum, therefore, causes the desire to  defaecate.   1 Superior rectal artery: This is the chief artery of the  rectum. It is the continuation of the inferior  mesenteric artery at the pelvic brim, medial to the  left ureter. It lies in medial limb of pelvic mesocolon  and divides opposite the third sacral vertebra into  right and left branches which run on each side of the  rectum. Each branch breaks up at the middle of the  rectum into several small branches which pierce the  muscular coats and run in the anal cohimns up to  the anal valves where they form looped anastomoses  (Fig. 33.6).    2 Middle rectal arteries: These supply only the superficial  coats of the lower rectum. They arise from the anterior  division of the internal iliac artery, run in the lateral  ligaments of rectum, and supply the muscle coats of  the lower part of the rectum (Fig. 33.6). Their  anastomoses with the adjacent arteries are poor.   3 Median sacral artery: This is a small branch arising  from the back of the aorta near its lower end. It  descends in the median plane and supplies the  posterior wall of the anorectal junction (see Figs 27.1  and 33.4).   1 Superior rectal vein: The tributaries of this vein begin  in the anal canal, from the internal rectal venous  plexus, in the form of about three veins of considerable  size. They pass upwards in the rectal submucosa,  pierce the muscular coat about 7.5 cm above the anus  and unite to form the superior rectal vein which  continues upwards as the inferior mesenteric vein to  end in the splenic vein (Fig. 33.6).   2 Middle rectal vein: The tributaries of this vein drain,  chiefly, the muscular walls of the rectal ampulla, and  open into the internal iliac veins (Fig. 33.6).   1 Lymphatics from more than the upper half of the  rectum pass along the superior rectal vessels to the  inferior mesenteric nodes after passing through the  pararectal and sigmoid nodes (Fig. 33.7).   2 Lymphatics from the lower half of the rectum pass  along the middle rectal vessels to the internal iliac  nodes.   3 Lymphatics from the lower part of anal canal drain  into superficial inguinal nodes.   The rectum is supplied by both sympathetic (LI, L2)  and parasympathetic (S2, S3, S4) nerves through the  superior rectal or inferior mesenteric and inferior  hypogastric plexuses.   Sympathetic nerves are vasoconstrictor, inhibitory  to the rectal musculature and motor to the internal  sphincter. Parasympathetic nerves are motor to the   Sensations of distension of the rectum pass through  the parasympathetic nerves, while pain sensations are  carried by both the sympathetic and parasympathetic  nerves.   1 Pelvic floor formed by levator ani muscles (see  Fig. 31.14).   2 Fascia of Waldeyer: It attaches the lower part of the  rectal ampulla to the sacrum. It is formed by  condensation of the pelvic fascia behind the rectum.  It encloses the superior rectal vessels and lymphatics.   3 Lateral ligaments of the rectum: They are formed by  condensation of the pelvic fascia on each side of the  rectum. They enclose the middle rectal vessels, and  branches of the pelvic plexuses, and attach the  rectum to the posterolateral walls of the lesser pelvis.   4 Rectovesical fascia ofDenonvilliers: It extends from the  rectum behind to the seminal vesicles and prostate  in front (see Fig. 32.3).   5 The pelvic peritoneum and the related vascular pedicles  also help in keeping the rectum in position (Fig. 33.3).    • Digital per rectum (PR) examination: In PR  examination the finger enters anal canal before  reaching lower end of rectum.   In a normal person, the following structures can  be palpated by a finger passed per rectum.   In patients, a PR examination can help in the  palpation of following abnormalities.   a. Within the lumen: Faecal impaction and foreign  bodies, bleeding piles or haemorrhoids.   b. In the rectal wall: Rectal growths and strictures,  and thrombosed piles.   c. Outside the rectal wall: In males, the enlarge¬  ments of prostate, seminal vesicles and  bulbourethral glands, and stone in membranous  urethra; in females, enlargements of uterus, tubes  and ovaries, and abnormalities in the pouch of  Douglas; and in both sexes, the distended  bladder, lower ureteric stones, and tumours of  the bony pelvis.   During parturition the dilatation of cervix is  commonly assessed through the rectal wall  to avoid infection by repeated vaginal examinations  (Fig. 33.9).   • Proctoscopy and sigmoidoscopy: The interior of the  rectum and anal canal can be examined under  direct vision with special instruments, like a  proctoscope or a sigmoidoscope. Proctoscopy  shows internal piles and growths in lower part of  rectum. Sigmoidoscopy helps in revealing the  ulcers, growths and diverticula, and in taking a  rectal biopsy.   • Prolapse of rectum: Incomplete or mucosal prolapse of  the rectum through the anus may occur following  violent straining. This is due to imperfect support  of the rectal mucosa by the submucosa which is  made up of loose areolar tissue.   Complete prolapse or procidentia is the condition  in which the whole thickness of the rectal wall  protrudes through the anus. The contributory  factors in its causation are:   • Neurological disturbances of the rectum: In spite of  the identical innervation of the rectum and  bladder, the rectal involvement in nervous lesions  is less severe than that of the bladder.   After sacral denervation of the rectum the  peripheral nervous plexus controls the automatic  evacuation of the rectum. This reflex activity is  more massive and complete when sacral  innervation is intact, e.g. complete cord lesion  above the sacral region. However, due to weak  musculature of the rectum and sparing of the tone  of the external sphincter by transverse lesions of  the cord, rectal disturbances tend to cause  constipation, although complete lesions may cause  reflex defaecation.   • Carcinoma of rectum: It is quite common, and is  generally situated at the rectosigmoid junction  (constricting type), or in the ampulla (proliferating  type). It causes bleeding per rectum from an  indurated raised ulcer. The condition is surgically  treated by an abdominoperineal excision in which  the anus, anal canal and rectum with their fascial  sheaths, and a varying amount of distal colon  along with its mesocolon containing the lymph  nodes are removed en bloc, and a permanent  colostomy in the left iliac fossa is done with the  proximal cut end of the colon.   • Rectal continence: Rectal continence depends solely  on the anorectal ring. Damage to the ring results  in rectal incontinence. The surgeon has to carefully  protect the anorectal ring in operating on the  region.   Identify the relations of the anal canal in both male and  female. Examine the lining of the anal canal. Strip the  mucous membrane and skin from a sector of the anal  canal. Identify the thickened part of the circular muscle  layer forming the internal sphincter of the anus. Locate  the external anal sphincter with its parts, partly  overlapping the internal sphincter. The anal canal is the  terminal part of the large intestine.   Anal canal is situated below the level of the pelvic  diaphragm. It lies in the anal triangle of perineum in  between the right and left ischioanal fossae, which  allows its expansion during passage of the faeces. The  sacculations and taeniae are absent here also.    coccyx in the cleft between the two buttocks. The  surrounding skin is pigmented and thrown into  radiating folds, and contains a ring of large apocrine  glands.   3 In females: Lower end of the vagina ( see Fig. 31.21).   All-round: Anal canal is surrounded by the sphincter  muscles, the tone of which keeps the canal closed.   The interior of the anal canal shows many important  features and can be divided into three parts: the upper  part about 15 mm long; the middle part about 15 mm  long; and the lower part about 8 mm long. Each part is  lined by a characteristic epithelium and reacts  differently to various diseases of this region (Fig. 33.10).   1 This part is about 15 mm long. It is lined by mucous  membrane, and is of endodermal origin.   a. 6 to 10 vertical folds; these folds are called the anal  columns of Morgagni.   b. The lower ends of the anal columns are united to  each other by short transverse folds of mucous  membrane; these folds are called the anal valves.   c. Above each valve there is a depression in the  mucosa which is called the anal sinus.   d. The anal valves together form a transverse line  that runs all-round the anal canal. This is the    The anal canal is 3.8 cm long. It extends from the  anorectal junction to the anus. It is directed downwards  and backwards. The anal canal is surrounded by inner  involuntary and outer voluntary sphincters which keep  the lumen closed in the form of an anteroposterior slit.   The anorectal junction is marked by the forward  convexity of the perineal flexure of the rectum  (Fig. 33.2) and lies 2-3 cm in front of and slightly below  the tip of the coccyx. Here the ampulla of the rectum  suddenly narrows and pierces the pelvic diaphragm.  In males it corresponds to the level of the apex of the  prostate.   The anus is the surface opening of the anal canal,  situated about 4 cm below and in front of the tip of the   pectinate line . It is situated opposite the middle of  internal anal sphincter, the junction of ectodermal  and endodermal parts. Occasionally the anal  valves show epithelial projections called anal  papillae . These papillae are remnants of the  embryonic anal membrane (Fig. 33.11).  e. The anal sinus contains anal glands. The secretion  of these glands produce peculiar small which is  important in lower animals to attract.   1 The next 15 mm or so of the anal canal is also lined  by mucous membrane, but anal columns are not  present here. The mucosa has a bluish appearance  because of a dense venous plexus that lies between  it and the muscle coat. The mucosa is less mobile  than in the upper part of the anal canal. This region  is referred to as the pecten or transitional zone. The  lower limit of the pecten often has a whitish  appearance because of which it is referred to as the  white line of Hilton. Hilton's line is situated at the level  of the interval between the subcutaneous part of  external anal sphincter and the lower border of  internal anal sphincter.   2 It marks the lower limit of pecten or stratified  squamous epithelium which is thin, pale and glossy  and is devoid of sweat glands.   It is about 8 mm long and is lined by true skin  containing sebaceous glands. The epithelium of the  lowest part resembles that of pigmented skin in which  sebaceous glands, sweat glands and hair are present.    Fig. 33.11: Coronal section through the wall of the anal canal   The internal anal sphincter is involuntary in nature. It is  formed by the thickened circular muscle coat of this  part of the gut. It surrounds the upper three-fourths,  i.e. 30 mm of the anal canal extending from the upper  end of the canal to the white line of Hilton.   The external anal sphincter is under voluntary control.  It is made up of a striated muscle and is supplied by  the inferior rectal nerve and the perineal branch of the  fourth sacral nerve. It surrounds the whole length of  the anal canal and has three parts, subcutaneous,  superficial and deep.   Contrary to earlier view, the external anal sphincter  forms a single functional and anatomic entity.  Uppermost fibres blend with fibres of puborectalis.  Anteriorly some fibres decussate with superficial  transverse perinei muscle and posterior fibres get  attached to anococcygeal raphe (Fig. 33.12a).   Middle fibres surround lower part of internal anal  sphincter. These are attached to perineal body  anteriorly and to coccyx via anococcygeal ligament  posteriorly. Some fibres of each side decussate to form  a commissure in the midline.   Lower fibres lie below the level of internal anal  sphincter and are separated from anal epithelium by  submucosa.   In males transverse perinei and bulbospongiosus end  in central point of perineum, so that there is a surgical  plane of cleavage between urogenital triangle and anal  canal.   In females, the puborectalis is separate from external  anal sphincter. Its anterior portion is thinner and shorter  (Fig. 33.12b).   In addition, in females, transverse perinei and  bulbospongiosus fuse with external anal sphincter in  lower part of perineum.   It is formed by fusion of the puborectalis with the  longitudinal muscle coat of the rectum at the anorectal  junction. It lies between the external and internal  sphincters. When traced downwards it becomes  fibroelastic and at the level of the white line it breaks  up into a number of fibroelastic septa which spread out  fan wise, pierce the subcutaneous part of the external  sphincter, and are attached to the skin around the anus  called as corrugator cutis ani. The most lateral of these  septa forms the perianal fascia. The most medial septum  forms, the anal intermuscular septum, which is attached  to the white line. In addition, some strands pass  obliquely through the internal sphincter and end in the  submucosa below the anal valves (Fig. 33.11).   Figs 33.12a and b: Relation of puborectalis and external anal sphincter (a) in male, and (b) in female   This is a muscular ring present at the anorectal junction.  It is formed by the fusion of the puborectalis, uppermost  fibres of external sphincter and the internal sphincter.  It is easily felt by a finger in the anal canal. Surgical  division of this ring results in rectal incontinence. The  ring is less marked anteriorly where the fibres of the  puborectalis are absent (Figs 33.12a and b).   1 The ischioanal space or fossa lies on each side of the  anal canal. It is described in Chapter 28.   2 The perianal space surrounds the anal canal below the  white line. It contains the lower fibres of external  sphincter, the external rectal venous plexus, and the  terminal branches of the inferior rectal vessels and  nerves. Pus in this space tends to spread to the anal  canal at the white line or to the surface of the perineal  skin rather than to the ischioanal space.   3 The submucous space of the canal lies above the white  line between the mucous membrane and the internal  sphincter. It contains the internal rectal venous  plexus and lymphatics (Fig. 33.13).   1 The part of the anal canal above the pectinate line is  supplied by the superior rectal artery.   2 The part below the pectinate line is supplied by the  inferior rectal arteries (Fig. 33.6).   1 The internal rectal venous plexus or haemorrhoidal  plexus lies in the submucosa of the anal canal. It  drains mainly into the superior rectal vein, but  communicates freely with the external plexus and  thus with the middle and inferior rectal veins. The  internal plexus is, therefore, an important site of  communication between the portal and systemic  veins. The internal plexus is in the form of a series of   dilated pouches connected by transverse branches  around the anal canal (Fig. 33.6).   Veins present in the three anal columns situated at  3, 7 and 11 o'clock positions as seen in the lithotomy  position are large and constitute potential sites for the  formation of primary internal piles (Fig. 33.14).   2 The external rectal venous plexus lies outside the  muscular coat of the rectum and anal canal, and  communicates freely with the internal plexus. The  lower part of the external plexus is drained by the  inferior rectal vein into internal pudendal vein; the  middle part by middle rectal vein into internal iliac  vein; and the upper part by superior rectal vein  which continues as the inferior mesenteric vein.   The anal veins are arranged radially around the anal  margin. They communicate with the internal rectal    plexus and with the inferior rectal veins. Excessive  straining during the defaecation may rupture one of  these veins, forming a subcutaneous perianal  haematoma known as external piles.   Lymph vessels from the part above the pectinate line,  drain with those of the rectum into the internal iliac  nodes.   Vessels from the part below the pectinate line drain  into the medial group of the superficial inguinal nodes  (Fig. 33.7).   1 Above the pectinate line , the anal canal is supplied by  autonomic nerves, both sympathetic (inferior  hypogastric plexus; LI, L2) and parasympathetic  (pelvic splanchnic, S2, S3, S4). Pain sensations are  carried by both of them.   2 Below the pectinate line, it is supplied by somatic  (inferior rectal, S2, S3, S4) nerves.   3 Sphincters: The internal sphincter is caused to contract  by sympathetic nerves and is relaxed by para¬  sympathetic nerves. The external sphincter is  supplied by the inferior rectal nerve and by the  perineal branch of the fourth sacral nerve.   Rectum: The mucous membrane of rectum has many  large folds. The epithelium and crypts contain abundant  goblet cells. Submucosa contains plexus of nerves and  capillaries. Muscularis externa is of uniform thickness.  Serosa is seen in upper part and adventitia in lower  part.   Anal canal: The epithelium lining of upper 15 mm is  simple or stratified columnar, while that of middle  15 mm is stratified squamous without any sweat gland  or sebaceous gland or hair follicle. The epithelium of  lowest 8 mm resembles that of true skin with sweat and  sebaceous glands and hair follicles.    The thick inner circular layer covers the upper three-  fourths of anal canal to form the internal anal sphincter.  The outer longitudinal layer is a thin layer. Outside  these smooth muscle layers is the striated external anal  sphincter.   The distal part of hindgut known as cloaca is divided  by urorectal septum into primitive anorectal canal  posteriorly and vesicourethral canal anteriorly.  Primitive anorectal canal forms the lower part of rectum  and proximal part of anal canal. Its distal part of anal  canal is formed by the proctodeum.   Upper part of rectum, i.e. part above the third  transverse fold of rectum, develops from endoderm of  hindgut. This part is related to peritoneum. Lower part,  below the third transverse fold, is formed from the  dorsal part of the cloaca. It is devoid of peritoneum.   Upper 15 mm develops from the primitive anorectal  canal. Lower part below the pectinate line (lower 15 +  8 mm) is formed from ectodermal invagination, i.e.  proctodeum (Greek on the way to). Non-continuity of  the two parts results in imperforate anus.   Table 33.1 shows comparison of upper and lower  parts of anal canal.    • Riles [haemorrhoids: Internal piles or true piles are  saccular dilatations of the internal rectal venous  plexus. They occur above the pectinate line and  are, therefore, painless. They bleed profusely  during straining at stool. The primary piles occur  in 3, 7 and 11 o'clock positions of the anal wall  when viewed in the lithotomy position. They are  formed by enlargement of the three main radicles  of the superior rectal vein which lie in the anal  columns, which occupy the left lateral, right  posterior, and right anterior positions (Fig. 33.14).  Varicosities in other positions of the lumen are  called secondary piles. The various factors  responsible for causing internal piles are;   a. Poor support to veins from the surrounding  loose connective tissue, so that the veins are less  capable of resisting increased blood pressure;   b. Absence of valves in the superior rectal and  portal veins;   c. Compression of the veins at the sites where they  pierce the muscular coat of the rectum; and   d. Direct transmission of the increased portal  pressure at the portosystemic communications.  For these reasons the development of piles is    Table 33.1: Comparison of upper (15 mm) and lower (23 mm) parts of anal canal    favoured by constipation, prolonged standing,  excessive straining at stool, and portal  hypertension.   External piles or false piles occur below the  pectinate line and are, therefore, very painful.  They do not bleed on straining at stool.   Fissure in ano: Anal fissure is caused by the rupture  of one of the anal valves, usually by the passage  of dry hard stool in a constipated person. Each  valve is lined with mucous membrane above, and  with skin below. Because of the involvement of  skin the condition is extremely painful and is  associated with marked spasm of the anal  sphincters.   Fistula in ano: A fistula is an abnormal epithelialised  track connecting two cavities, or one cavity with  the exterior (see Fig. 28.10).   Fistula in ano is caused by spontaneous rupture  of an abscess around the anus or may follow  surgical drainage of the abscess. Most of these  abscesses are formed by the small vestigial glands  opening into the anal sinuses. Such an anorectal  abscess tends to track in various directions and  may open medially into the anal sinus, laterally  into the ischioanal fossa, inferiorly at the surface,  and superiorly into the rectum. A fistula can also  be caused by an ischioanal or a pelvirectal abscess.  The fistula is said to be complete when it opens  both internally into the lumen of the gut and  externally at the surface.   c. Anorectal agenesis with or without a fistula.  Most of the anorectal malformations are caused  by abnormal partitioning of the cloaca by the  urorectal septum.    • Middle lateral curvature of rectum is most  prominent. It is convex to the left side.   • Chief artery of rectum is superior rectal and chief  vein is superior rectal vein.   • Perineal body and levator ani form the main  supports of rectum.   • Most of the anal canal is surrounded by internal  and external anal sphincters.   • Only middle fibres of external anal sphincter have  a bony attachment.   • Proximal 15 mm of anal canal develops from  anorectal canal (endoderm) and distal 23 mm  develops from the proctodaeum (ectoderm)    A female patient aged 40 years complained of a  painless, bleeding with some structure coming out  of anus at the time of defaecation   Ans: The patient has developed internal haemo¬  rrhoids or piles. These are due to prolapse of the  mucous membrane containing the tributaries of  internal rectal venous plexus draining blood from  the anal canal. Since this part of mucous membrane  is supplied by autonomic nerves, these piles are not  painful. Since these contain varicose venous radicles,  these rupture due to pressure, resulting in painless  bleeding during defaecation.   These types of piles may result from irregular  bowel habits, chronic constipation, too much  straining during defaecation and also in case of portal  hypertension resulting due to liver cirrhosis.   3. Which artery supplies the posterior part of anorectal  junction and posterior part of anal canal?   a. Mucous membrane b. Muscle layers  c. Connective tissue d. All of the above   a. Superior rectal b. Middle rectal  c. Inferior rectal d. All of the above   7. Which part of sphincter ani externus has a bony  attachment?    All the pelvic viscera, i.e. terminal parts of digestive  and urinary system; and components of genital system  are located in the pelvis. These organs are provided  due protection and nutrition by the bones, muscles,  fascia, blood vessels, lymphatics and nerves of the  pelvis. The posterior superior iliac spine seen as a  dimple (mostly covered) lies opposite the middle of the  sacroiliac joint.   Contents: In this chapter the vessels, nerves, muscles,  fascia, and joints of the pelvis will be considered.   Remove the viscera from the pelvic wall and the pelvic  cavity. Trace the internal iliac artery and its two divisions.  Follow the branches of each of its divisions to the  position of the viscera and the parieties. Remove the  veins and venous plexuses as these obstruct the view  of the arteries. Clean the hypogastric plexus.    superior vesical artery, and the rest of it degenerates  into a fibrous cord, the medial umbilical ligament.   The internal iliac artery begins in front of the sacroiliac  joint, at the level of the intervertebral disc between the  fifth lumbar vertebra and the sacrum. Here it lies medial  to the psoas major muscle. The artery runs downwards  and backwards, and ends near the upper margin of the  greater sciatic notch, by dividing into anterior and  posterior divisions or trunks (Fig. 34.1).    Ureter. In female to the ovary and lateral  end of the uterine tube (see Fig. 31.1)  Internal iliac vein, lumbosacral trunk and  the sacroiliac joint (see Figs 24.27 and 34.7)  External iliac vessels and obturator nerve  (Fig. 34.1)   Peritoneum and to a few tributaries of the  internal iliac vein.   The internal iliac artery is the smaller terminal branch  of the common iliac artery. It is 3.75 cm long. It supplies:   1 Pelvic organs except those supplied by the superior  rectal, ovarian and median sacral arteries.   In the foetus, internal iliac artery is double the size  of the external iliac artery because it transmits blood to  the placenta through the umbilical artery. The umbilical  artery with the internal iliac then forms the direct  continuation of the common iliac artery. After birth the  proximal part of the umbilical artery persists to form   In the female, it gives off seven branches. The inferior  vesical artery is replaced by the vaginal artery. The  uterine artery is the seventh branch.   ' Superior vesical artery  Deep circumflex iliac artery  Inferior epigastric artery   Fig. 34.1: Branches of the right internal iliac artery in a male   1 Inferior gluteal artery: It is the largest branch of the  anterior division of the internal iliac artery. It is the  axial artery of the lower limb. It supplies chiefly the  buttock and the back of the thigh. In the pelvis, it  runs downwards in front of the sacral plexus and  piriformis. Next, it pierces the parietal pelvic fascia,  passes below the first sacral nerve and then between  the piriformis and the coccygeus, and enters the  gluteal region through the lower part of the greater  sciatic foramen (Fig. 34.2). In the pelvis, it supplies:   b. Vesical branches to the base of the bladder, the  seminal vesicles and the prostate.   2 Obturator artery: It runs forwards and downwards  on the obturator fascia below the obturator nerve and  above the obturator vein (NAV). Medially, it is  crossed by the ureter and the ductus deferens, and  is covered with peritoneum. It passes through the  obturator foramen to leave the pelvis and enter the  thigh. In the pelvis it gives off:   c. A pubic branch to the peritoneum on the back of  the pubis, which anastomoses with the pubic  branch of the inferior epigastric artery and with  its fellow of the opposite side.   Fig. 34.2: Anterior view of the right sacral and coccygeal plexuses   1 Superior vesical artery: The proximal 2.5 cm or so of  the superior vesical artery represents the persistent  part of the umbilical artery. It supplies many  branches to the upper part of the urinary bladder.  One of these branches gives off the artery to the  ductus deferens.   b. Very little of its blood goes to the rectum, and that  too goes only to its muscle coats.   c. Most of its blood goes to the prostate and seminal    3 Inferior vesical artery: It supplies the trigone of the  bladder, the prostate, the seminal vesicles, and the  lower part of the ureter.   4 Internal pudendal artery: It is the smaller terminal  branch of the anterior division of the internal iliac  artery. It supplies the perineum and external  genitalia. Its branches are inferior rectal, perineal,  artery to bulb, urethra, deep and dorsal arteries. It is  described in Chapter 28.   5 Vaginal artery: It corresponds to the inferior vesical  artery of the male, and supplies the vagina, the bulb  of the vestibule, the base of the urinary bladder, and  the adjacent part of the rectum (see Chapter 31).   6 Uterine artery: It has a tortuous course. Crosses the  ureter 2 cm lateral to cervix. Runs along side of  uterus. Supplies vagina, cervix uterus, fallopian tube  (see Chapter 31).   1 Iliolumbar artery: It runs upwards in front of the  sacroiliac joint and lumbosacral trunk, and behind  the obturator nerve and external iliac vessels  (Fig. 34.1). Behind the psoas major, it divides into  the lumbar and iliac branches.   The lumbar branch represents the fifth lumbar  artery, and supplies the psoas, the quadratus  lumborum and the erector spinae. Its spinal branch  supplies the cauda equina.   The iliac branch supplies the iliac fossa and the  iliacus. It participates in the anastomoses around the  anterior superior iliac spine.   2 Lateral sacral arteries: These are usually two in  number, upper and lower. They run downwards and  medially over the sacral nerves. Their branches enter  the four anterior sacral foramina to supply the    contents of the sacral canal. Their terminations pass  out through the posterior sacral foramina and  supply the muscles and skin on the back of the  sacrum (see Fig. 33.4).   3 Superior gluteal artery: It rims backwards, pierces the  pelvic fascia, passes above the first sacral nerve, and  leaves the pelvis through the greater sciatic foramen  above the piriformis (Fig. 34.2). It supplies gluteus  maximus muscle. Also takes part in anastomoses  around anterior superior iliac spine and in  trochanteric anastomoses to supply nearby muscles  and overlying skin. For further course see Chapter 5.   It ascends posteromedial to the internal iliac artery, and  joins the external iliac vein to form the common iliac  vein at the pelvic brim, in front of the lower part of the  sacroiliac joint. Its tributaries correspond with the  branches of the artery, except for the iliolumbar vein  which joins the common iliac vein. The tributaries are  as follows.   1 Rectal venous plexus is drained by the superior,  middle and inferior rectal veins.   2 Prostatic venous plexus is drained by the vesical and  internal iliac veins.   1 The common iliac nodes 4 to 6 receive lymphatics from  The external and internal iliac nodes, and send their  efferents to the lateral aortic nodes.   2 The external iliac nodes 8 to 10 receive lymphatics from  the inguinal nodes, the deeper layers of the  infraumbilical part of the anterior abdominal wall,  the membranous urethra, the prostate, the base of  the urinary bladder, the uterine cervix, and part of  the vagina. Their efferents pass to the common iliac  nodes. The inferior epigastric and circumflex iliac nodes  are outlying members of this group.   3 The internal iliac nodes receive lymphatics from all  the pelvic viscera, the deeper parts of the perineum,  and muscles of the buttocks and of the back of the  thigh. Their efferents pass to the common iliac nodes.  The sacral and obturator nodes are outlying members  of this group.   Expose the lumbosacral trunk and ventral rami of sacral  one to sacral five nerves. Lift the sacral plexus forwards  and expose its terminal branches, the sciatic and  pudendal nerves.   Find the nerves arising from the dorsal surface of  plexus, e.g. superior gluteal, inferior gluteal, perforating  cutaneous and perineal branch of fourth sacral nerve.   Trace the two branches, e.g. nerve to quadratus  femoris and nerve to obturator internus arising from the  pelvic surface of the plexus.   Trace the sympathetic trunks in the pelvis till these  terminate in the single ganglion impar on the coccyx.  Trace the large grey rami communicans from the ganglia  to the ventral rami of the sacral nerves.   Find the inferior hypogastric plexus around the  internal iliac vessels. In addition, trace the pelvic  splanchnic nerves reaching the inferior hypogastric  plexus from the ventral rami of second, third and fourth  sacral nerves.   The lumbosacral plexus is formed by the lumbosacral  trunk and the ventral rami of the first to third sacral  nerves, and part of the fourth sacral nerve (Fig. 34.2).   The lumbosacral trunk is formed by the descending  branch of the ventral ramus of nerve L4 and the whole  of ventral ramus L5. The trunk descends over the ala  of the sacrum, crosses the pelvic brim in front of the  sacroiliac joint, and joins nerve SI ( see Fig. 33.4).   Nerves SI and S2 are large. The other sacral nerves  become progressively smaller in size.   1 The lumbosacral trunk and ramus SI are separated  from each other by the superior gluteal vessels. Both  lie in front of the sacroiliac joint before passing on to  the surface of the piriformis. Thus both may be  involved in pathological conditions of the joint (Fig.  34.2).   2 Ramus SI is separated from ramus S2 by the inferior  gluteal vessels.   3 Rami S2, S3 and a part of S4 lie between the anterior  surface of the piriformis and the pelvic fascia.   4 The main plexus lies in front of the piriformis deep  to the pelvic fascia, and behind the internal iliac  vessels and the ureter (Fig. 34.4).   1 Each ventral ramus receives a grey ramus communicans  from the sympathetic chain at the anterior sacral  foramen.   2 Before uniting to form the plexus, the ventral rami  give off:   b. Twigs to the levator ani, the coccygeus and the  sphincter ani externus (S4).   3 The plexus gives rise to two main branches namely,  the sciatic and pudendal nerves, concerned  respectively with locomotion and reproduction.   4 As in other plexuses, the rami tend to divide into  ventral and dorsal divisions which supply the  corresponding aspects of the lower limb and trunk.  In general, the dorsal divisions supply the extensors  and the abductors, and the ventral divisions supply  the flexors and the adductors, of the limb.   Branches derived from both dorsal and ventral  divisions are as follows.   1 Sciatic nerve: The common peroneal nerve component  arises from dorsal divisions of L4, L5, SI, S2. It  supplies evertors of foot and dorsiflexors of ankle   joint. The tibial nerve component arises from ventral  divisions of L4, L5, SI, S2, S3. It supplies the  hamstring muscles, all muscles of calf and intrinsic  muscles of the sole. This nerve is described in  Chapter 7.   2 Posterior cutaneous nerve of thigh: Dorsal divisions of  SI, S2 and ventral divisions of S2, S3 ( see Chapter 7).   1 Superior gluteal nerve: L4, L5, SI ( see Fig. 5.14).   2 'Inferior gluteal nerve: L5, SI, S2 ( see Fig. 5.14).   3 Pudendal nerve: S2, S3, S4: Supplies sphincter ani  externus and all muscles in urogenital triangles.   4 Muscular branches to the levator ani, the coccygeus  and the sphincter ani externus, including perineal  branch of nerve S4.   Nerves to the levator ani or iliococcygeus part and the  coccygeus or ischiococcygeus arise from nerve S4 and  enter their pelvic surfaces.   The nerve to the middle part of the sphincter ani  externus is called the perineal branch of the fourth sacral  nerve. It runs forwards on the coccygeus and reaches  the ischioanal fossa by passing between the coccygeus  and the levator ani. In addition to the lower end of  external sphincter, it supplies the skin between the anus  and the coccyx.   1 It is formed by the ventral rami of spinal nerves S4  (descending branch), S5 and the coccygeal nerve  (Fig. 34.2).   2 The three nerves join on the pelvic surface of the  coccygeus to form a small plexus known as the  coccygeal plexus.   3 The plexus gives off the anococcygeal nerves, which  pierce the sacrotuberous ligament and supply the  skin in the region of the coccyx.    The lumbosacral trunk (L4, L5) and the ventral ramus  of nerve SI cross the pelvic surface of the joint and  may be involved in disease of the joint, causing pain  in the area of their distribution below the knee. L4  supplies medial aspect of leg and sole. SI supplies  lateral aspect of sole refer (see Fig. 10.2).   The pelvic part of the sympathetic chain runs  downwards and slightly medially over the body of  sacrum, and then along the medial margins of the  anterior sacral foramina. The two chains unite in front  of the coccyx to form a small ganglion impar. The chain  bears four sacral ganglia on each side and the single  ganglion impar in the central part.   a. Grey rami communicans to all sacral and  coccygeal ventral rami.   b. Branches to the inferior hypogastric plexus from  the upper ganglia.   c. Branches to the median sacral artery from the  lower ganglia.   e. Branches to the glomus coccygeum (see Fig. 29.11)  from the ganglion impar.   The inferior hypogastric plexus (see Chapter 27) one  on each side of the rectum and other pelvic viscera is  formed by the corresponding hypogastric nerve from  the superior hypogastric plexus; branches from the  upper ganglia of the sacral sympathetic chain; and the  pelvic splanchnic nerves. Branches of the plexus  accompany the visceral branches of the internal iliac  artery; and are named:   The nervi erigentes represent the sacral outflow of the  parasympathetic nervous system. The nerves arise as  fine filaments from the ventral rami of S2, S3 and S4.  They join the inferior hypogastric plexus and are  distributed to the pelvic organs. Some parasympathetic  fibres ascend with the hypogastric nerve to the superior  hypogastric plexus and thence to the inferior mesenteric  plexus. Others ascend independently and directly to  the part of the colon derived from the hindgut.   The pelvic fascia is distributed in the extraperitoneal  space of the pelvis. It covers the lateral pelvic wall  and the pelvic floor called parietal pelvic fascia; and  also surrounds the pelvic viscera called visceral pelvic  fascia.    1 The fascia is dense and membranous over  nonexpansile structures, e.g. lateral pelvic wall, but  is only loosely arranged over expansile structures,  e.g. viscera, and over mobile structures, e.g. the  pelvic floor (Fig. 34.3).   2 As a rule the fascia does not extend over bare bones;  at the margins of the muscles it fuses with the  periosteum. In this respect, the fascia of Waldeyer is  an exception, which extends from the sacrum to the  ampulla of rectum.   1 The fascia covering the muscles of the lateral pelvic  wall is condensed to form thick and strong  membranes. It is closely adherent to the walls of the  pelvic cavity. It is attached along a line from  iliopectineal line to the inferior border of pubic bone.   2 The fascia covering the obturator internus is called  the obturator fascia. It shows a linear thickening or  tendinous arch for the origin of the levator ani. Below  this origin it is closely related to the lunate fascia  and to the pudendal canal.   3 The fascia covering the piriformis is thin. The nerves  over the piriformis, i.e. the sacral plexus lie external  to the pelvic fascia and, therefore, do not pierce the  fascia while passing out of the pelvis. The gluteal  vessels, on the other hand, lie internal to the pelvic  fascia and, therefore, have to pierce the fascia while  passing out of the pelvis (Fig. 34.4).   1 The pelvic fascia covers both the surfaces of the pelvic  diaphragm, forming the superior and inferior layers.  The inferior fascia is also known as the anal fascia.   2 In general, the fascia of the pelvic floor is loosely  arranged between the peritoneum and the pelvic  floor, forming a dead space for distension of the  bladder, the rectum, the uterus and the vagina.  Because of the loose nature of the fascia infections  can spread rapidly within it.    Fig. 34.4: Arrangement of structures on the walls of true pelvis   3 However, the fascia is condensed at places to form  fibromuscular ligaments which support the pelvic  viscera. The various ligaments are dealt with  individual viscera including the prostate, bladder,  uterus and the rectum.   This fascia surrounds the extraperitoneal parts of the  pelvic viscera. It is loose and cellular around distensible  organs like bladder, rectum and vagina, but is dense  around non-distensible organs, like the prostate. The  visceral layer is attached along a line extending from  the middle of back of pubis to the ischial spine.   Identify the origin of piriformis from the ventral surface  of the sacrum. Trace it through the greater sciatic  foramen to its insertion into the upper border of greater  trochanter of femur.   Feel the ischial spine and trace the fibres of  coccygeus and levator ani that arise from it. Trace the  origin of levator ani from thickened fascia, i.e. tendinous  arch over the middle of obturator internus muscle till  the back of body of the pubis. Note that the right and  left sheet like levator ani muscles are united and the  muscles are inserted into central perineal tendon or  perineal body, anal canal, anococcygeal ligament.   Detach the origin of levator ani from obturator fascia.  While removing obturator fascia identify pudendal canal  with its contents in the lower part of the fascia.   Trace the tendon of obturator internus muscle. This  tendon along with superior and inferior gemelli muscles  leaves through the lesser sciatic foramen to be inserted  into the medial surface of greater trochanter of femur.   1 Piriformis and obturator internus, which are short  lateral rotators of the hip joint and are described with  the muscles of the lower limb.   2 Levator ani and coccygeus, which with the  corresponding muscles of the opposite side, form the  pelvic diaphragm. The diaphragm separates the  pelvis from the perineum (Figs 34.5a and b).   The levator ani and coccygeus may be regarded as  one morphological entity, divisible from before  backwards into the pubococcygeus, the iliococcygeus  and the ischiococcygeus or coccygeus. They have a  continuous linear origin from the pelvic surface of the  body of the pubis, the obturator fascia or white line or  tendinous arch and the ischial spine. The muscle fibres  slope downwards and backwards to the midline,  making a gutter-shaped pelvic floor. These muscles are  described below.    Fig. 34.6: The levator ani, the coccygeus and the piriformis in  a female    rectum. In female the anterior portion of puborectalis  is thinner and shorter (see Fig. 33.12b).   3 The posterior fibres of the pubococcygeus arise from  the anterior half of the white line on the obturator  fascia. These get attached to anococcygeal ligament  and tip of coccyx.   1 The anterior fibres of this part arise from the medial  part of the pelvic surface of the body of the pubis. In  the male these fibres closely surround the prostate  and constitute the levator prostatae. In the female these  fibres surround the vagina and form the sphincter  vaginae. In both cases the anterior fibres are inserted  into the perineal body.   2 The middle fibres constitute the puborectalis. These  arise from the lateral part of the pelvic surface of the  body of the pubis. They partly form a loop or sling  around the anorectal junction; and are partly  continuous with the longitudinal muscle coat of the   1 The posterior half of the white line on the obturator  fascia.   2 The pelvic surface of the ischial spine. They are  inserted into the anococcygeal ligament and into the  side of the last two pieces of coccyx.   This muscle represents the posterior or ischiococcygeus  part of the pelvic diaphragm. It is triangular in shape.  It is partly muscular and partly tendinous.   b. The sacrospinous ligament. It is inserted into the  side of the coccyx, and into the fifth sacral vertebra.    Figs 34.5a and b: (a) Interlocking hands represent the enterlocking fibres of two levator ani muscles, and (b) openings in the pelvic  diaphragm in female   1 The levatores ani and coccygeus close The posterior  part of the pelvic outlet.   2 The levators ani fix the perineal body and support  the pelvic viscera.   3 During coughing, sneezing, lifting and other  muscular efforts, the levators ani and coccygei  counteract or resist increased intra-abdominal  pressure and help to maintain continence of the  bladder and the rectum.   In micturition, defaecation and parturition, a  particular pelvic outlet is open, but contraction of  fibres around other openings resists increased intra¬  abdominal pressure and prevents any prolapse  through the pelvic floor. The increase in the intra¬  abdominal pressure is momentary in coughing and  sneezing and is more prolonged in yawning,  micturition, defaecation and lifting heavy weights.  It is most prolonged and intense in second stage of  labour.   4 The coccygeus pulls forwards and support the  coccyx, after it has been pressed backwards during  defaecation, parturition or childbirth.   1 The superior or pelvic surface is covered with pelvic  fascia which separates it from the bladder, prostate,  rectum and the peritoneum.   2 The inferior or perineal surface is covered with anal  fascia and forms the medial boundary of the  ischioanal fossa (see Fig. 28.7).   3 The anterior borders of the two muscles are separated  by a triangular space for the passage of the urethra  and the vagina (Fig. 34.5b).   4 The posterior border is free and lies against the  anterior margin of coccygeus (Fig. 34.6).   1 In lower mammals, both the pubococcygeus and the  iliococcygeus are inserted only into the coccygeal  vertebrae and are responsible for movements of the  tail. With the disappearance of the tail during  evolution, the muscles have been modified to form  the pelvic diaphragm which supports the viscera.  Such support became necessary with the adoption  of the erect posture by man.    2 In lower mammals, the levator ani arises from the  pelvic brim. In man, the origin has shifted down to  the side wall of the pelvis.   3 The coccygeus muscle corresponds exactly with the  sacrospinous ligament, which is a degenerated part  of the aponeurosis of this muscle. The two are  inversely proportional in their development.    The muscles of the pelvic floor may be injured during  parturition. When the perineal body is torn, and has  not been repaired satisfactorily, the contraction of  anterior fibres of the levator ani increases the normal  gap in the pelvic floor, instead of decreasing it. This  results in prolapse of the uterus.   Remove the remains of any muscle of the back or  thoracolumbar fascia. Identify the iliolumbar and dorsal  sacroiliac ligaments. Remove the dorsal sacroiliac  ligament to identify the deeply placed interosseous  sacroiliac ligament. Divide this interosseous ligament  and open the joint from the posterior aspect.   Define the attachments of ventral sacroiliac ligament.  Cut through this thin ligament to open the sacroiliac  joint.   1 The joints and ligaments between the fifth lumbar  vertebra and the base of the sacrum are similar to  those between any two typical vertebrae. The  lumbosacral disc is very thick, and is thickest  anteriorly.   2 The stability of the fifth lumbar vertebra on the  sacrum is further increased by:   b. Strong iliolumbar ligament which extends from the  stout transverse process of the fifth lumbar  vertebra to the iliac crest. The ligament fans out  interiorly to be attached to the lateral part of  the ala of the sacrum as the lumbosacral ligament  (Figs 34.7a and b).    Figs 34.7a to c: Articular surfaces of the right sacroiliac joint, (a) Medial view of the upper part of the right hip bone, (b) right lateral  view of the sacrum, and (c) lumbosacral angle is 120° opening backwards    3 The body of the fifth lumbar vertebra makes an  angle of about 120 degrees opens backwards with  the sacrum. This is the lumbosacral or sacrovertebral  angle, and opens backwards (Fig. 34.7c).   4 This region is subject to a number of variations which  give rise to symptoms of backache. These are:   The sacrococcygeal joint is a secondary cartilaginous joint  between the apex of the sacrum and the base of the  coccyx. The bones are united by:   3 Deep dorsal sacrococcygeal ligament corresponding  to the posterior longitudinal ligament.   4 Superficial dorsal sacrococcygeal ligament,  completing the lower part of the sacral canal.   5 Lateral sacrococcygeal ligament corresponding to the  intertransverse ligament and completing the foramen  for the fifth sacral nerve.   6 Intercornual ligament, connecting the cornua of the  sacrum and the coccyx. In old age the joint is  obliterated and the ligaments are ossified. Sometimes  the joint is synovial, and the coccyx is freely mobile.  The inter coccygeal joints are present only in young   subjects. Fusion of the segments begins at the age of 20  years and is complete by about 30 years.   This is a synovial joint of the plane variety. The articular  surfaces are flat in infants; but in adults show  interlocking irregularities which discourage move¬  ments at this joint.   1 Auricular surface of the sacrum, which is covered  with fibrocartilage.   2 Auricular surface of the ilium, which is covered with  hyaline cartilage (Fig. 34.7).   1 The fibrous capsule is attached close to the margins of  the articular surfaces. It is lined by synovial  membrane (Fig. 34.8).   2 The ventral sacroiliac ligament is a thickening of the  anterior and inferior parts of the fibrous capsule. Its  lower part is attached to the preauricular sulcus.   3 The interosseous sacroiliac ligament is massive and very  strong, forming the chief bond of union between the  sacrum and the ilium. It connects the wide, rough  areas adjoining the concave margins of the auricular  surfaces, and is covered by the dorsal sacroiliac  ligament.   4 The dorsal sacroiliac ligament covers the interosseous  sacroiliac ligament, from which it is separated by  the dorsal rami of the sacral spinal nerves and  vessels.   a. Short transverse fibres or short posterior sacroiliac  ligament passing from the ilium to the transverse  tubercles of the first two sacral pieces.   b. A long, more vertical, band or long posterior sacroiliac  ligament passing from the posterior superior iliac  spine to the transverse tubercles of the third and  fourth sacral pieces; it is continuous laterally with  medial edge of the sacrotuberous ligament.   The vertebropelvic ligaments include the iliolumbar,  sacrotuberous and sacrospinous ligaments. These are  accessory ligaments to the sacroiliac joint and are  important in maintaining its stability.   a. The iliolumbar ligament is a strong, triangular  ligament, extending from the thick transverse  process of the fifth lumbar vertebra to the posterior  part of the inner lip of the iliac crest. It is  continuous with the middle and anterior layers  of the thoracolumbar fascia and gives partial  origin to the quadratus lumborum. It is covered  anteriorly by the psoas, and posteriorly by the  erector spinae. It prevents anteroinferior slipping  of the fifth lumbar vertebra under the influence  of body weight, and also prevents forward  movement at the sacroiliac joint (Fig. 34.8).   b. The sacrotuberous ligament is a long and strong  band which forms parts of the boundaries of the  pelvic outlet and of the sciatic foramina. Its  superomedial end or base is wide. It is attached  to the posterior superior and posterior inferior iliac  spines, the lower transverse tubercles of the  sacrum, the lateral margin of the lower part of the  sacrum and the upper part of the coccyx. The  inferolateral end is narrow. It is attached to the  medial margin of the ischial tuberosity. A part of    it that extends along the ramus of the ischium is  called the falciform process. The ligament is  covered by and also gives partial origin to gluteus  maximus, and is pierced by the perforating  cutaneous nerve, the fifth sacral and first coccygeal  nerves, and branches of the coccygeal plexus (see  Figs 5.14 and 34.8).   c. The sacrospinous ligament is a thin, triangular  ligament, which lies deep to sacrotuberous  ligament, and separates the greater and lesser  sciatic foramina. Its base is attached to the lateral  margins of the last piece of the sacrum and to the  coccyx and its apex to the ischial spine. Its pelvic  surface is covered by and also gives origin to the  coccygeus. Morphologically, the ligament is a  degenerated part of the coccygeus (Fig. 34.8).   1 Joint is covered by the erector spinae, the gluteus  maximus and the sacrotuberous ligament (Fig. 34.7b).   2 Dimple overlying the posterior superior iliac spine  lies opposite the middle of joint (see Fig. 5.1).   1 It is covered by the psoas and iliacus (see Fig. 2.5).   2 Deep to the psoas, the joint is crossed by the iliolumbar  vessels and the obturator nerve (see Fig. 15.11).   3 Femoral nerve is separated from the joint by the  iliacus muscle.   1 Lumbosacral trunk and the posterior division of the  internal iliac artery.   2 Internal iliac vein and the anterior division of the  internal iliac artery.   3 Superior gluteal vessels and the first sacral nerve (SI)  (Fig. 34.2).   Stability is the primary requirement of the joint as it  transmits body weight from the vertebral column to  the lower limbs. Stability is maintained by a number of  factors which are as follows.   2 Thick and strong interosseous and dorsal sacroiliac  ligaments play a very important role in maintaining  stability (Fig. 34.7).   3 Vertebropelvic ligaments, i.e. iliolumbar, sacro-  tuberous and sacrospinous, are equally important in  this respect.   4 With advancing age, partial synostosis of the joint  takes place which further reduces movements.   Sacroiliac joint is supplied by twigs from all the three  branches of posterior division of internal iliac artery, i.e.  iliolumbar, lateral sacral and superior gluteal arteries.   2 Ventral rami and the lateral branches of dorsal rami  of the first and second sacral nerves.   During flexion and extension of the trunk, stooping and  straightening, i.e. the sacroiliac joint permits a small  amount of anteroposterior rotatory movement around a  transverse axis passing 5 to 10 cm vertically below the  sacral promontory. This little movement serves the  important function of absorbing the shocks of jumping  and bearing of loads. The range of movement is  increased temporarily in pregnancy in which all the  ligaments of the pelvis become loose, under the  influence of hormones, to facilitate delivery of the foetus.   This is a secondary cartilaginous joint between the  bodies of the right and left pubic bones. Each articular  surface is covered with a thin layer of hyaline cartilage.  The fibrocartilaginous disc is reinforced by surrounding  ligamentous fibres. The fibres are thickest interiorly  where they form the arcuate pubic ligament. Anteriorly,  the fibres form the anterior pubic ligament (see Fig. 15.14a).    The pubic symphysis permits slight movement  between the hip bones, which helps in absorbing shocks.  The range of movement is increased during pregnancy.   The most important mechanical function of the pelvis  is to transmit the weight of trunk to the lower limb.  The weight passes mainly through the alae of sacrum  and through the thick part of hip bone lying between  sacroiliac joint and acetabulum.   Theoretically, the weight falling on the lumbosacral  joint is divided into two components.   a. One component of the force is expanded in trying to  drive the sacrum downwards and backwards  between the iliac bones. This is resisted by the  ligaments of pubic symphysis.   b. Second component of the force tries to push the upper  end of sacrum downwards and forwards towards  the pelvic cavity. This is resisted by the middle  segment of the sacroiliac joint, where the auricular  surface of the sacrum is wider posteriorly, i.e.  wedge-shaped and is concave for interlocking  with the reciprocal surface of the ilium.   Because of the poor wedging and poor locking of  the articular surfaces in the anterior and posterior  segments of the sacroiliac joint, the sacrum is forced to  rotate under the influence of body weight. In this  rotation, the anterior segment is tilted downwards and  the posterior segment upwards. The downward tilt of  the anterior segment is prevented chiefly by the dorsal  and interosseous sacroiliac ligaments; and the upward  tilt of the posterior segment is prevented chiefly by the  sacrotuberous and sacrospinous ligaments.   During all these movements the separation of iliac  bones is resisted by sacroiliac and iliolumbar ligaments,  and the ligaments of pubic symphysis.    • During pregnancy the pelvic joints and ligaments  are relaxed, so that the range of movement is  increased and locking mechanism becomes less  efficient. This naturally puts greater strain on the  ligaments. The sacroiliac strain thus produced may  persist even after pregnancy.   After childbirth the ligaments are tightened up  again, so that the locking mechanism returns to its  original efficiency. Sometimes locking occurs in the  rotated position of the hip bones adopted during  pregnancy. This results in subluxation of the joint,  causing low backache due to strain on ligaments.   * The diseases of the lumbosacral and sacroiliac joints  can be differentiated by the following tests.   a. In lumbosacral lesions, the tenderness is present  over the spines and above the dimple of posterior   superior iliac spine (over the iliolumbar  ligament); in sacroiliac lesions, the tenderness  is located inferomedial to the dimple (over the  posterior sacroiliac ligament) (Fig. 34.9).   b. In lumbosacral disease, the movements of  vertebral column are restricted in all directions;  in sacroiliac disease, the movements are free,  except for extreme forward bending, when the  tension on hamstrings causes backward rotation  of the hip bones, opposite to that of sacrum,  producing pain in a diseased joint.    • Inferior gluteal artery is the largest branch of  anterior division of internal iliac artery. It is also  part of the axial artery of lower limb.   • Pelvic viscera are supported by pelvic diaphragm  formed by levator ani and coccygeus muscles in  the large posterior part of pelvic outlet. In its small  anterior part, the muscles of urogenital region  support the viscera.   • Uterine artery is the additional artery exclusively  in the female.   • Ventral ramus of L4 nerve takes part both in  formation of lumbar plexus as well as sacral plexus  and is called nervi furcalis.   • Nerves forming sacral plexus lie outside the  parietal layer of pelvic fascia. Blood vessels of the  pelvis lie inside the parietal layer.   • Interosseous sacroiliac ligament is the strongest  ligament of the body.   • The free anastomoses between superior rectal vein  of portal and the middle and inferior rectal veins  of the caval system explain the metastases in the  liver from cancers of the genital organs.   • The sensory nerve supply of the ovary and  fallopian tube is from T10-T12 nerves.    An elderly person was hit by a speeding car. As he   fell down, he was run over by the vehicle. He was   • What type of joints are pubic symphysis and  sacroiliac joints?   • Pubic bone of one side is fractured and sacroiliac  joint of the other side is dislocated.   • Pelvic ring comprises of pubic rami, acetabulum,  ischium, ilium and sacrum.   • Pubic symphysis is secondary cartilaginous joint  and sacroiliac joint is plane synovial joint.    1. Following are the branches of anterior division of  the internal iliac artery except :   2. Following are the branches of posterior division of  internal iliac artery except :   3. Branches of anterior division of internal iliac artery  in female are as follows except :   5.. Parts of levator ani are as follows except :  a. Pubococcygeus b. Iliococcygeus    Two horizontal (transpyloric'and transtubercular) and  two vertical (right and left lateral) planes divide the  abdomen into nine regions (Fig. 35.1). These are  described in Chapter 18.   1 It is marked on the left side of the back, with its long  axis corresponding with that of the 10th rib.   2 The upper border corresponds to the upper border  of the 9th rib, and the lower border to the lower  border of the 11th rib (Fig. 35.2).   3 The medial end lies 4 to 5 cm from the posterior  midline; and the lateral end on the left midaxillary  line.   1 Cardiac orifice: It is marked by two short parallel lines  2 cm apart, directed downwards and to the left on  7th costal cartilage, 2.5 cm to the left of median plane  (Fig. 35.3). 
bdchaurasiashumananatomyvolume3headneckandbrain6thedition_201909 BD Chaurasia’s Human Anatomy, Volume 2 – Lower Limb, Abdoman and Pelvis, 6th Edition_djvu.txt