Aspiration is diagnostic and mandatory in patients with suspected septic arthritis. It is a lso recommended if patients have crystal arthritis or haemarthosis. Aspiration is therapeut ic in patients with tense effusions, to remove irritants such as pus, which damages cartila ge and to facili- tate joint lavage in septic arthritis. Injectable therapies \200 The commonest injected agents are local anesthetic and steroid therapy. There is evidence t o support use of steroids in in \202 ammatory arthritis and osteoarthritis, as well as som e soft tissue conditions. However, because steroid injections have been used for many years in routine practice, the evidence base is less robust than for newer therapies, which have been introduced more recently. Sclerosants have been used for many years in the treat- men t of soft tissue and spinal disease, despite a limited evidence base for their ef \201 cac y. Hyalgan therapy has a role in the treatment of early osteoarthritis, but is not currentl y supported by National Institute of Clinical Excellence (NICE). More novel agents include autologous blood, botulinum toxin, and heparin. However, the evidence base for these therap ies is poor and no randomized controlled trials have been published to date. Route of injection Injections may be delivered into: \200 \200 \200 \200 Joints. Tendon sheaths. Bursae. Muscle. Injections may also be delivered around nerves to i nduce nerve blockade. Tendons are structurally hard and injecting substances into tendons i s therefore dif \201 cult. Dry-needling tendons has a role in the treatment of calci \201 c tendinitis, and plantar fasciitis. Dry needling is believed to induce a local in \202 a mmatory reaction, which then is then followed by tissue regeneration. Indications for injections Magnetic resonance (MR) studies have con \201 rmed the ef \201 cacy of intra-articular steroid injection in reducing syno- vitis in rheumatoid arthritis. The effect of the steroid is greater if arthrocentesis is performed prior to administratio n of the steroid and the joint aspirated to dryness. In osteo- arthritis, the largest liter ature surrounds injections into the knee. It is estimated that around 1 in 4 with osteoarth ritis of the knee will respond to an intra-articular steroid injec- tion, but identifying t he subgroup who will respond is com- plex. There is a growing literature supporting the ef \201 cacy of steroid into and around soft tissue lesions, although in general this remains an under researched area. Complications Local anesthetic Injection of local anesthetic is relatively safe, but cardia c toxicity limits the dose of anesthetic, which can be injected. Contraindications to arthrocentesis/injections There are no absolute contraindications to a rthrocentesis or joint or soft tissue injections. However, there are some instanced where s pecial precautions are required. \200 Steroid therapy Injection of steroid has a greater number of potential side effects, althou gh many of those reported are rare and by association. Patients should, however, be warned about these prior to the procedure being performed. \200 Bleeding diathesis or anticoagulation. Anticoagulation is not a contraindication to joint o r soft tissue injection, but the INR should be checked prior to the procedure and the proce dure abandoned if the INR is greater than 3. In patients with an INR lower than this, there is an increased risk of haemarthrosis. It is common practice to apply an ice pack after th e procedure to increase vaso- constriction in anticoagulated patients. Prosthetic joints. P rostheses may become infected, but arthrocentesis carries the risk of introduction of infec tion The risk of sepsis following injection is estimated to be between 1 in 15 000 and 1 in 50 0 00 injections. There are no observational studies, and the estimation has been extrapolated from arthroscopic data. Patients who develop a hot, swollen joint after injection should b e investigated and treated as those with a de novo swollen joint (see chapter 16 p. 446). CHAPTER 4 Rheumatological procedures: injection therapy 107 and should only be undertaken by orthopedic surgeons in the sterile environment of theaters . Infection of the overlying skin is a contraindication to arthrocentesis as infection may be introduced into an otherwise sterile joint. No response to previous injection if there h as been no response to a previous injection, the rationale of repeating the procedure shoul d be questioned. While hydrocortisone is easily mixed with local anaes- thetic, methylprednisolone forms a v isible sediment, as does triamcinolone, although this is less marked than with methylpredni solone. The volume of local anesthetic de- pends on the joint to be injected, but normally a volume of 2 \200\2234 ml is suf \201 cient. If a number of joints are to be injected at the same visit, the cumulative dose of local anesthetic should be calculated to ensure toxi city does not occur. The side effects of local anesthetic include allergy, so patients shou ld be observed for 30 min following injection, and especially in high doses as there is a r isk of cardiac toxicity. Ef \201 cacy of different preparations The steroid preparations used have a strong glucoco rticoid action and less of a mineralocorticoid action, therefore optimizing the anti-in \202 ammatory response. The commonest preparations are hydrocortisone, which is relatively short acting, but may have a slightly weaker glucocorticoid action, and methylprednisolone and triamcinolone, which are both longer acting. The longer-acting preparations are used fo r large joint injections, and the shorter acting for small joints and soft tissue lesions. See table 4.1 for suggested doses. Frequency of injections Soft tissue injections can be repeated after an interval of 3 \200 \2236 weeks and joint injections may be repeated after a period of 3 \200\2234 months. In a patient requiring more frequent injections, for example, in a patient with rheumatoid arth ritis, the overall disease management should be reviewed. Table 4.3 Dose and maximum safe volumes of local anesthetic Table 4.1 Suggested doses for steroid injections Drug Strength Maximum safe dose Depomedrone/- methylprednisolone 80 mg Knee 40 mg Ankle Lidocaine 1% 20 ml Wrist 2% 10 ml Elbow Procaine 1% 100 ml Shoulder 2% 50 ml Plantar fasciitis Bupivacaine 0.25% 60 ml Hydrocortisone 25 mg Epicondylitis 0.5% 30 ml 10 \200\22325 mg Carpal tunnel Rest Ef \201 cacy in knee injections is improved in patients who rest for 24 \200\22348 h after injection. It is reasonable to extend this advice to all who receive soft tissue and joint injections, advising avoidance of heavy manual activities for 2 weeks. Tenosynovitis Local anesthetic Local anesthetic is useful both diagnostically and thera- peutically. In c ases where the diagnosis is not clear cut, accurately injected local anesthetic may abolish symp- toms, making a diagnosis more obvious. Local anesthetic is used for the majority of injections as it reduces the initial pain of a post-injection \202 are. Accuracy of injection There ef \201 cacy of a joint injection is greater if the steroid an d local anesthetic are injected directly into the joint, rather than into the periarticular soft tissues. The accuracy is improved if the injection is undertaken under image guidance , and increasingly, USS is used to increase accuracy of injections. Table 4.2 Basic pharmacokinetics of commonly used local anesthetics Drug Onset of action Duration of action Lidocaine 1 \200\2232 min 1 h Procaine 1 min 30 min Bupivacaine 30 min 8 h PROCEDURE 108 Procedure Preparation of equipment \200 The needle and syringes should be disposed of in a sharps bin. The patient should be reasse ssed after the procedure, and the procedure recorded in the medical notes. A number of different needles and syringes are available. Selection of the correct needle l ength is important and if arthrocentesis is to be undertaken, a narrow bore needle will not allow passage of viscous \202 uid. If a large volume of synovial \202 uid is to be asp irated, a container or a number of syringes must be available. A sterile universal containe r is necessary if synovial \202 uid is to be sent for analysis. The steroid and local ane sthetic should be mixed in advance, and the doses and expiry dates checked. Once the drugs are drawn up, a clean needle should be attached to the syringe. Current recommendation is t hat gloves be worn during the procedure to protect the clinician against potential infectio n from bodily \202 uids. These do not need to be sterile. Injection techniques Shoulder girdle Glenohumeral joint The glenohumeral joint is most easi ly accessed from the posterior approach. From behind, palpate the tip of the acromion and i dentify the corocoid process. The needle should be inserted perpendicular to the skin, 2.5 cm inferi- orly and 2.5 cm medially to the tip of the acromion, with the tip of the needle aiming towards the corocoid process. Preparation of the patient \200 The patient should be warned about the potential complication. The procedure should be expl ained and informed consent obtained. The patient should be comfortable, with relaxed muscle s around the site to be injected. The site of entry should be marked in the skin, either us ing pressure of the needle sheath or using a pen. The skin should be cleaned with an antise ptic. The skin should be allowed to dry before the procedure as it is the drying of the ant iseptic, such as alcohol, which kills skin \202 ora. Administration of the injection \200 A no touch technique should be used, so that once the skin has been cleaned, it is not touc hed again. Injections should not be painful. The most uncomfortable part of the procedure s hould be the needle moving through the skin. The concentration of sensory nerve endings is higher on the skin of the hands and feet, and lower in areas such as the shoulder. In the m ajority of cases, local anesthetic is not required separately to the skin, but con \201 de nt introduction of the needle into the correct site will cause little discomfort. Once the needle is in place, aspiration should be under- taken to ensure the needle is not in a bloo d vessel. If it is, the needle should be removed, pressure applied over the puncture site u ntil bleeding has stopped, and the procedure repeated with the needle repositioned. If syno vial \202 uid is aspirated, the joint should be aspirated to dryness. If there is concern about the possibility of infection, steroid should not be administered and synovial \202 uid sent for analysis. The local anesthetic/steroid combination should \202 ow without r esistance. If resistance is experienced, the needle tip may be up against bone and small ad justments to the needle position are necessary. Once the injection has been administered, t he needle may be withdrawn and pressure applied over the site to prevent bleeding. A plaste r should be applied if there is no history of allergy to plasters. Fig 4.1 Posterior approach to the glenohumeral joint \200 The anterior approach requires the needle to be inserted just medially to the corocoid proc ess. The ante- rior approach is less commonly use than the posterior due to the relative pr oximity of the large vessels and brachial plexus. Needle: 21G, inserted approximately 4 cm. Steroid: depomedrone 40 mgB. \200 CHAPTER 4 Rheumatological procedures: injection therapy 109 Sternoclavicular joint \200 The sternocalvicular joint is best accessed with the patient \200\231s arm in external rota tion. The joint is accessed from a superiolateral approach, with the needle angled down and into the joint. Needle: 25G, inserted 1 cm. Steroid: depomedrone 20 mg. \200 Fig 4.2 Anterior approach to the glenohumeral joint Fig 4.4 Approach to the sternoclavicular joint. Acromioclavicular joint \200 Subacromial space and rotator cuff \200 The acromioclavicular joint is identi \201 ed 1 cm medially from the tip of the acromion. It can be felt to move when the shoulder is shrugged. The patient sits with their arm handi ng by their side and the needle is inserted at an angle of 30 medially as the joint sits at an angle. This can be a dif \201 cult joint to inject, but \200\230walking \200\231 th e needle slowly and gently across the acromion can help in identi- fying the acromioclavicu lar joint. Needle: 25G, inserted 1 cm. Steroid: depomedrone 20 mg. The patient sits with the arm hanging by their side. This opens up the subacromial space be tween the acromion and humeral head. The lateral edge of the acromion should be palpated an d the needle inserted below the midpoint of the acromion. Needle: 21G, inserted 3 cm. Stero id: depomedrone 40 mg. \200 \200 Fig 4.5 Approach to the subacromial bursa Fig 4.3 Approach to the acromioclavicular joint PROCEDURE 110 Medial epicondylitis \200 The elbow region The elbow capsule \200 The patient sits with the arm supported and in exten- sion. The medial epicondyle is identi \201 ed and the needle inserted perpendicular to the anterior facet until bone is touched . The steroid combination should be injected in a fan like approach over the bone. Needle: 25 G, inserted 1 cm. Steroid: hydrocortisone 10 \200\22325 mg. The elbow capsule houses the radio-humeral, radioulnar and humero-ulnar joints. The joint i s most easily accessed from a lateral approach. The patient sits with the elbow at 90 of \202 exion. The needle is inserted into the space between the head of the radius and the o lecranon proc- ess of the humerus, with the needle parallel to the top of the radius. Needl e: 25G, inserted 2 cm. Steroid: depomedrone 40 mg. \200 \200 Fig 4.8 Approach for medical epicondylitis Olecranon bursa \200 The patient sits with the elbow \202 exed to 90 . The area of tenderness is palpated and the needle inserted into the central tenderness. Needle: 23G. Steroid: hydrocortisone 25 m g. \200 Fig 4.6 Lateral approach to the elbow joint Lateral epicondylitis \200 The patient sits with the elbow at 90 and the arm supported. The lateral epicondyle is pa lpated and the needle inserted in line with the cubital crease. The ster- oid combination s hould be injected in a fan like approach over the bone. Needle: 25G, inserted 1 cm. Steroid : hydrocortisone 10 \200\22325 mg. \200 Fig 4.9 Approach for the olecranon bursa Wrist and hand Wrist \200 The hand is placed palm down, and just proximal to the capitate is a hollow, within the mid carpus bones. The needle is inserted into the hollow. Needle: 23G, inserted 2 cm. Steroid: depomedrone 40 mg. \200 Fig 4.7 Approach for lateral epicondylitis CHAPTER 4 Rheumatological procedures: injection therapy 111 Thumb carpometacarpal joint \200 The arm is positioned on the ulnar border of the fore- arm with the thumb uppermost. The jo int space between the trapezium and the metacarpal is easily identi \201 ed. Traction on t he thumb helps to open up the joint space. The needle may be inserted in to the joint. Need le: 25G, inserted 0.5 cm Steroid: hydrocortisone 10 mg \200 Fig 4.10 Approach to the wrist Distal radioulnar joint \200 The hand is placed palm down, and the joint line identi- \201 ed midway between the radia l and ulnar styloids. The needle is inserted perpendicular to the skin. Needle: 25G, insert ed by 1.5 cm. Steroid: depomedrone 40 mg. \200 Fig 4.12 Approach to the carpometacarpal joint De Quervain \200\231s tenosynovitis \200 The arm is positioned on the ulnar border of the fore- arm with the thumb uppermost. The ab ductor pollicus longus and extensor pollicis brevis tendons run together in one tendon shea th. The gap between the tendons is identi \201 ed and the needle inserted into the gap. As the injection is administered, there may be a swelling as the \202 uid moves out of the opposite end of the tendon sheath. Needle: 25G, inserted 0.5 cm. Steroid: hydrocortisone 10 mg. \200 Fig 4.11 Approach to the radioulnar joint PROCEDURE 112 Trigger \201 nger \200 A nodule is often palpable at the base of the \201 nger in the \202 exor tendon sheath. The nodule is directly injected with steroid. Needle: 25G, inserted 0.5 cm. Steroid: hydro cortisone 10 mg. \200 Fig 4.13 Approach for de Quervan \200\231s tenosynovitis Carpal tunnel syndrome \200 The hand is placed with the palm facing up. Identify the proximal wrist crease. The palmaru s longus tendon should be identi \201 ed. The needle should be inserted on the ulnar side of the palmarus longus tendon at an angle of 45 with the needle aiming towards the tip of the third (middle) \201 nger. If there is acute worsening of pain and numbness in the di stribution of the median nerve, the needle should be removed and repositioned as is within the median nerve. Patients should be warned that the symptoms may deteriorate in severe car pal tunnel due to increase in pressure around the nerve. Local anaes- thetic is not normall y administered as local anesthetic may worsen the paraesthesia in the short term. Needle: 2 3G, inserted 1.5 cm. Steroid: hydrocortisone 25 mg. Fig 4.15 Approach for trigger \201 nger The hip region The hip \200 The hip is a deep joint and should only be injected under radiological guidance. Needle 21G , inserted by around 4 cm. Steroid: depomedrone 80 mg. \200 \200 Trochanteric bursitis \200 The patient lies on their side with the painful hip upper- most. The site of maximum tender ness is palpated over the greater trochanter. The needle is injected perpen- dicular to the skin and the steroid and local anesthetic mixture injected in a fan like approach in the t ender region. Needle: 21G, inserted 4 cm. Steroid: depomedrone 40 mg. \200 Fig 4.14 Approach to the carpal tunnel CHAPTER 4 Rheumatological procedures: injection therapy 113 Coronary ligament \200 The knee is bent to 90 and the foot of that leg exter- nally rotated. The tibial plateau is palpated to \201 nd the area of tenderness, and the needle is inserted on to the plate au. Needle: 25G, inserted 2 cm. Steroid: hydrocortisone 25 mg. \200 Medial collateral ligament \200 The knee is supported in slight \202 exion and the medial joint line identi \201 ed. The area of tenderness is palpated and the needle inserted to the point of tenderness, but not deep enough to penetrate the joint capsule. Needle: 25G, inserted 2 cm. Steroid: hydrocort isone 25 mg. \200 Infrapatellar bursa \200 The knee is slightly \202 exed and supported. The deep infrapatellar burse sits beneath t he patellar tendon and the needle is inserted beneath the tendon, either from a medial or a lateral approach. It is important not to insert the needle into the patellar tendon. Needl e: 23G, inserted 2 cm. Steroid: hydrocortisone 25 mg. \200 Fig 4.16 Approach for trochanteric bursitis Adductor tendinitis \200 The patient lies on their back with the leg abducted and laterally rotated. The origin of t he tendon is identi \201 ed and the needle inserted on to the bone at that point. The ster oid is peppered around the origin of the tendon. Needle: 23G, inserted 1.5 cm. Steroid: hyd rocortisone 25 mg \200 The knee region The knee \200 Fig 4.18 Approach to the infrapatellar bursa The patient is positioned on lying on their back with the knee in slight \202 exion and s upported. Either a medial or a lateral approach can be taken. The medial approach requires identi \201 cation of the midpoint of the patellar and insertion of the needle under the p atella and above the femoral condyle. In the lateral approach, the same technique is applie d, but from the lateral aspect (see Plate 23). Needle: 21G, inserted 3 \200\2234 cm. Steroi d: depomedrone 80 mg. Anserine bursa \200 The knee is supported in extension. The pes anserine tendon is identi \201 ed by \202 ex ing the knee against resist- ance. The point of insertion can be palpated on the tibia, and the bursa lies deep to this, and is tender. The needle is inserted into the central area o f tenderness, and onto the bone. Needle: 23G, inserted 2 cm. Steroid: hydrocortisone 25 mg. \200 \200 Fig 4.17 Medial approach to the knee PROCEDURE 114 \200 Needle 25G. Steroid: depomedrone 40 mg. First metatarsal phalangeal joint. \200 The patient lies with the foot supported. The joint line can be palpated and identi \201 e d by passively moving the great toe. The needle is inserted perpendicularly, avoid- ing the extensor tendon in the midline. Needle: 25G, inserted 1 cm. Steroid: hydrocortisone 25 mg. \200 Fig 4.19 Approach for the anserine bursa Ankle and foot Ankle mortice \200 The foot is supported in neutral. The ankle joint lies between the lateral and medial malle oli, and the ankle joint may be followed laterally, and identi \201 ed by passively \202 exing and extending the ankle. The needle is inserted directly into the joint, passing thr ough the capsule. Needle: 23G, inserted 2 cm. Steroid: depomedrone 40 mg. \200 Fig 4.21 Approach to the \201 rst metatarsophalangeal joint The Achilles tendon and bursa. \200 The Achilles tendon should not be injected as there is no tendon sheath, and injection may result in rupture. The Achilles bursa sits beneath the Achilles tendon and should be inject ed under ultrasound control. Needle 23G, inserted 2 cm. Steroid: hydrocortisone 25 mg. \200 The peroneal tendons \200 The patient lies supine. The two tendons of peroneus longus and brevis share a tendon sheat h which can be identi \201 ed by palpation. The needle should be inserted between the two tendons and the needle slid towards the lateral malleolus. This should ensure the needle is within the tendon sheath. Needle: 25G, inserted 1 cm. Steroid: Hydrocortisone 25 g. \200 Fig 4.20 Approach to the ankle mortice joint Subtalar joint and midtarsal joints \200 The subtalar and midtarsal joints are difficult to access blindly and should therefore be i njected under ultrasound control. CHAPTER 4 Rheumatological procedures: injection therapy 115 Procedure \200 \200 Informed consent should be obtained. The patient should be examined to measure the angle of the straight leg raise. Blood pressure should be measured. The patient lies prone with the abdomen supported by a pillow. If patients are uncomfortable lying in this position, it is possible for the procedure to be performed with the patient lying on their side. At the to p of the buttocks, a small bony protruberance is palpable on the sacrum at S4 and S5 under which lies a sacral hiatus. This should be marked and the skin steri- lized with iodine or a similar antiseptic. Local anesthetic, such as 2 ml of 2% lidocaine should be applied to t he skin. Whilst this is working the epidural solution should be drawn up. This consists of 5 ml of bupivacaine 0.25%, 80 mg of depomedrone and 10 ml of sterile normal saline. Using e ither a 21G needle, or a spinal needle, the needle is inserted through the sacral hiatus at an angle of 45 directed towards the umbilicus. No resistance should be encountered. With the needle in the hiatus, the syringe should be detached and the patient asked to cough. T his is to ensure the dura has not been perforated. If cerebrospinal \202 uid is seen, the procedure must be abandoned. The epidural should be slowly introduced into the epi- dural space over a period of a minute of two. The patient may feel a pushing sensation in the low back. The needle is then removed. A plaster can be applied to the puncture site. Blood pre ssure should be monitored immediately and then after 15 and 30 min. The straight leg raise should be examined again before the patient is discharge. The epidural may be repeated, par ticularly if there has been a response to the previous epidural. It is not clear how often or what the interval should be between epidural injections. Fig 4.22 Approach to the peroneal tendon sheath Plantar fasciitis \200 The patient lies with foot relaxed. The needle should be aimed at the calcaneum, having bee n inserted either from a lateral approach through the soft tissues, or from the soft part o f the sole of the foot. Needle: 21G, inserted 2 \200\2233 cm. Steroid: depomedrone 40 mg. \200 Caudal (sacral) epidural Caudal epidurals are performed for low back pain with radicular sy mptoms. Potential complications include wors- ening of radicular symptoms, headache, hypote nsion, infec- tion, the risk of which is similar to that of iatrogenic joint infection, and spinal block. \200 Fig 4.23 Approach for plantar fascilitis Fig 4.24 Approach for a caudal epidural PROCEDURE 116 Further reading Dangoisse MJ, et al. Suprasacpular nerve block (using bupivacaine and methy lprednisolone acetate] in chronic shoulder pain. Acta Anaesthesiol Belg 1994; 45: 49 \200 \22354. Speed CA. Injection therapies for soft-tissue lesions. Best Pract Res Clin Rheumatol 2007; 21: 333 \200\22347. Fig 4.25 Approach for a suprascapular nerve block Suprascapular nerve block The suprascapular nerve provides sensory \201 bres to the acrom ioclavicular joint and to the shoulder joint. \200 The technique involves injecting anesthetic into the \202 oor of the supraspinatus fossa to block the nerve. The solution of 8 ml of 0.5% bupivicaine and 80 mg depomedrone should b e drawn up in advance. Informed consent must be obtained having explained the potential com plications of pneumothorax, and damage to the suprascapular nerve and vessels. A sterile, n o touch approach should be undertaken. The skin is cleaned with iodine or another antisepti c. The spine of the scapula is identi \201 ed and the needle is inserted into the fossa, 1 cm cephalad to the middle of the spine of the scapula and into the \202 oor of the fossa . The solution should be injected slowly. Patients should be observed for an hour after the procedure. \200 \200 \200 117 Chapter 5 Regional musculoskeletal anatomy and conditions The spine 118 Cervical spine: regional musculoskeletal conditions 124 Thoracic spine and ch est wall: regional musculoskeletal conditions 128 Lumbar spine: regional musculoskeletal co nditions 130 The shoulder 136 The shoulder girdle: regional musculoskeletal conditions 140 The elbow 146 The elbow: regional musculoskeletal conditions 148 The hand and wrist 152 Han d and wrist: regional musculoskeletal conditions 158 Pelvis, hip, and groin 164 Pelvis, hip and groin: regional musculoskeletal conditions 168 The knee 174 The knee: regional musculo skeletal conditions 178 Lower leg and foot 184 Lower leg and foot: regional musculoskeletal conditions 188 Conditions of the ankle and hindfoot 190 Conditions of the mid and forefoot 194 THE SPINE 118 The spine pedicles to the posterior elements. The posterior elements comprise the lamina, the superio r and inferior articular processes, the transverse processes, and the spinous pro- cesses. The facet joints articulate via a true synovial joint. This is especially relevant in rheum atoid arthritis. The ver- tebral body consists predominantly of cancellous bone surrounded by a cortical shell. Between them they resist the compressive forces applied to the anterio r part of the spinal column. The vertebral body on its superior and infe- rior surfaces is covered by a layer of cartilage beneath which lies a condensation of bone referred to as th e sub- chondral plate. The subchondral plate is perforated by nutrient arteries which in ch ildhood form end-arterioles The spine is the central axis of the body. The cervical and lumbar vertebrae provide flexib ility and the thoracic spine along with the ribs provides a protective cage for the content s of the thorax. Regional anatomy The spinal column consists of seven cervical, twelve thoracic and \201 v e lumbar vertebrae. It also consists of \201 ve fused sacral segments and the fused coccy geal segments. See Figure 5.1. Bones The overall structure of each vertebra is similar with some regional variation. Each consists of a vertebral body, which constitutes the anterior element and this is joined via odontoid process atlas axis cervical spinous processes cervical neural arches 7 C7 3 T3 1st rib 7 thoracic thoracic T7 transverse processes 6th rib intervertebral foramena 12 12th rib laminae lumbar lumbar inter cristal plane vertebral bodies sacrum site for lumbar puncture coccyx (a) (b) Figure 5.1 Vertebral column: (a) lateral view; (b) posterior view. CHAPTER 5 Regional musculoskeletal anatomy and conditions 119 within the cartilaginous endplate. The loss of vascularity associated with advancing age ha s been implicated as one of the causes of disc degeneration. cervical and lumber spine. The transverse processes bear facets for the tubercles of the ri bs. The thoracic vertebral foramena are relatively small. See Figure 5.2. Cervical spine In the cervical spine the lateral ends of the superior part of the C3 \200 \223C6 vertebral bodies \202 are out to form the uncinate processes, which articulate wit h the under surface of the cervical vertebra cranial to it. The transverse processes have b ecome adapted and contain a foramen transversar- ium, which accommodates the vertebral arte ry from the C6 up to the C1 level. The \201 rst and second cervical verte- brae are atypi cal. The vertebral body of C1 is, in fact, part of the C2 vertebra and presents as a crania l projection of the C2 body that is known as the odontoid peg. The C1 vertebra, therefore, is more like a ring than a typical verte- bra. The articulations between the skull and the atlas (C1 vertebra), and the C1 and C2 vertebra (axis) are relatively \202 attened. This allows a signi \201 cant range of movement particularly with regard to rotation in the tra nsverse plane. The odontoid process on the body of C2 allows identi \201 ca- tion of this vertebra. The facet joints on this vertebral body articulate with the anterior arch of the atlas on the ante- rior surface and with the transverse ligament of the atlas on the poster ior aspect. The articulations between the other cervical vertebrae are inclined at approxim ately 45 to the transverse plane. This accounts for the signi \201 cant degree of \202 exion that is achievable in the cervical spine. Lumbar spine The facet joints in the lumbar region are inclined at approximately 45 to th e coronal plane. Pure movements such as \202 exion, extension, and rotation of the spine are rare in that such movements often elicit a so called cou- pled movement in another plan e. For example, axial rota- tion of the cervical spine is associated with lateral \202 ex ion as a consequence of coupled movement. See Figure 5.3. Intervertebral disks The vertebrae are separated anteriorly by intervertebral disks. These constitute a tough outer ring referred to as the annulus \201 brosis with a central nucle us pulposus. See Figure 5.4. The annulus consists of concentric rings of collagen \201 - bres, which resist rotational forces within the spine, as well as tensile forces. The nucle us consists predominantly of water that accounts for more than 70% of the nuclear con- tent . It also contains a collagenous matrix, as well as pro- teoglycans and mucopolysaccharides . The cell content is extremely low and consists mainly of chondrocyte-like cells. The disc is bound superiorly and inferiorly by cartilaginous endplates, which are comprised of hyal ine cartilage. (a) Thoracic spine Each thoracic vertebra is larger than that immediately above it. Each has an upper and lower hemifacet joint which articulates with the heads of the ribs. The spinous processes are long in comparison with those of the spinal nerve hemi articulation for head of rib spinous process articulation for tubercle of rib annulus fibrosus nucleus pulposus superior articular facet (b) pedicle posterior primary ramus inferior articular facet Figure 5.2 Typical thoracic vertebra (T5) from side. superior articular facet pedicle body anterior primary ramus lamina Figure 5.4 (a) Lumbar intervertebral disc viewed from below. (b) Prolapse of nucleus pulpos us ( \200\230slipped disc \200\231). spinous process Ligaments The ligaments of the spine are classi \201 ed as long or short. The short ligame nts include: \200 Interspinous ligaments, which attach adjacent spinous processes. Intertransverse ligaments, which attach adjacent trans- verse processes. inferior articular facet Figure 5.3 Typical lumbar vertebra (L4) from above and the side. THE SPINE 120 Ligamenta \202 avum, elastic ligaments, which attach to the laminae of adjacent arches. T he long ligaments include: The anterior longitudinal ligament on the anterior surface of th e vertebral bodies. The posterior longitudinal ligament on the posterior surface of the ver tebral bodies. The supraspinous ligament, which attaches to the tip of the spinous processe s. exits the spinal cord cranial to the C1 vertebra and this dictates the nomenclature of all the nerve roots thereafter. The C8 nerve root exits the spine cranial to the T1 verte- bra and the T1 root, therefore, exits under the pedicle of T1. This pattern is continued in the lumbar spine. For example, the L5 nerve root exits under the L5 pedicle in the L5/S1 exit foramen. This is of particular importance in nomenclature with respect to neural compressio n. Spinal tracts The spinal cord has an ellipsoid cross-section and has a central H-shaped are a referred to as the gray matter, which contains the cell bodies. The surrounding white mat ter contains the ascending and descending columns of nerve \201 bres. The white matter is divided anatomically into the posterior white column, the lateral white column and the ant erior white column. The alar ligaments extend from the top and sides of the odontoid peg to the foramen magnum. The cruciate ligament is the name given to the transverse ligament of the atlas. Muscles Longus colli and longus capitus extend from the base of the skull to the upper thor acic vertebrae with attachments to the cervical vertebrae and result in \202 exion of the cervi- cal spine. In the lumbar spine, \202 exion is primarily achieved by contraction o f the psoas muscles, a powerful paraverte- bral muscle whose origin is the transverse proce sses of the lumbar vertebrae and insertion is the lesser trochanter of the femur. Lateral \202 exion is achieved by contraction of the scalene muscles, the origin of which is the t ransverse pro- cesses of the cervical vertebrae, and insertion is the \201 rst and second ribs. Extension of the spine arises due to the action of short, deep muscles that attach t ransverse pro- cesses to adjacent spinous processes, more super \201 cial me- dium length muscles, and longer, superficial muscles including the erector spinae muscles. Afferent impulses usually enter the spinal cord via the \201 rst order neurons, whose cel l bodies reside in the poste- rior root ganglion of the spinal nerves. These synapse with s econd order neurons, which are usually located in the spinal cord. Subsequent synapses are on to third order neurons whose cell bodies reside in the thalamus, although this is a fair ly simplistic schema, and in reality several varia- tions and complex patterns exist. The efferent pathways are divided in to the direct cortical spinal or pyramidal system and the indirect cortical spinal or extra pyramidal system. The pyramidal system originates wit h cell bodies in the cerebral cortex with \201 bres extending directly onto the anterior horn cells within the spinal cord. In the extra pyramidal system, the cortical \201 bres synapse with intermediate neurons located either in the pons, cerebellum, thalamus, or any other number of nuclei. Cells from these intermediate nuclei then project on to the anterio r horn cells and this accounts for the reference to this system as an indirect cortical spi nal pathway. Anatomy of the spinal cord In the adult human, the spinal cord extends from the foramen mag num to its termination at approximately the L1/2 disc space. In the fetus, the cord extends down to the lower lumbar segments, but the termination of the cord migrates cranially due to the greater velocity of longitudinal growth of the spinal column compared with the spina l cord. At birth, the cord terminates at the L1/2 level. As a conse- quence of this the ner ve roots in the cervical region exit almost transversely from the cord whereas distal to th e L1 level the nerve roots follow an oblique course until they exit through their respectiv e foraminae. The C1 nerve root Dermatomes Main nerve roots supplying the lower limb \200 Hip: \200 Knee: \200 \200 Ankle: \200 \200 Subtalar joint: \200 \200 Toes: \200 \200 \200 \202 exion, adduction L2, 3, 4. extension, abduction L4, 5, S1; extension L3, 4. Main nerve roots supplying muscles of the upper limb \200 Shoulder: \200 \200 Elbow: \200 \200 Forearm: \200 \200 Wrist: \200 Fingers: \200 Hand: \200 abduction, lateral rotation C5; adduction, medial rotation C6, 7, 8. \202 exion L5, S1; plantar \202 exion L4, 5. \202 exion C5, 6; extension C7, 8. dorsi \202 exion L5, S1; inversion L5. supination C6; pronation C7, 8. eversion, plantar \202 exion L5, S1; \202 exion L5, S1, 2; dorsi \202 exion S1, 2, 3. \202 exion and extension C6, 7. \202 exors and extensors C7, 8. intrinsic muscles C8, T1. CHAPTER 5 Regional musculoskeletal anatomy and conditions 121 C2 C3 C2 C3 C4 T4 T2 T4 T7 T2 T2 T7 T10 C5 C5 C5 C5 T12 L1 T1 T1 C6 C6 T10 T1 T1 L3 C6 S5 T12 L2 L2 S4 C6 L1 L1 C8 S3 S3 C8 C8 C8 L2 L2 C7 C7 C7 C7 S2 S2 L3 L3 L3 L3 L5 L5 L5 L5 L4 L4 L4 L4 S1 S1 S1 S1 L5 L5 Figure 5.5 Dematome chart. Ascending tracts The three principle ascending tracts are: \200 \201 bres located more laterally and therefore more super \201 - cially in the cord. Ant erior and posterior spinal cerebellar tracts are responsible for unconscious proprioception and trans- mit information from the periphery to the cerebellum. Posterior gracile and cuneate tracts: the gracile tracts transmit \201 bres from the lowe r limb and trunk, and the cunate tracts from the upper limb and trunk. They convey proprioc eptive impulses and light touch and vibration sensibility. Anterior lateral tract: afferent \201 bres from the periph- ery cross to the contralateral side of the spinal cord and al so usually ascend to a variable extent. They may do so for over up to 5 segments. Ten per c ent of \201 bres within the anterior lateral tract synapse in the thalamus and are usuall y responsible for perception of super \201 cial pain, such as pin prick. Eighty per cent o f the \201 bres in the anterior lateral tract are, in fact spinoreticular thalamic \201 bres and reach the thalamus after synapsing in the reticular nucleus. These are responsibl e for deep pain perception such as muscle squeeze. These \201 bres are laminated with sac ral Descending tracts \200 \200 The three principle descending tracts are: The lateral cortical spinal tracts, which are fo rmed from the motor decussation in the lower medulla are the principle motor tracts. The re ticular spinal tracts, which modulate activity of the anterior horn cells, are divided into a lateral and medial reticular spinal tract. The lateral vestibular spinal tracts transmit information from the vestibular nucleus of the medulla to the ante- rior horn cells, and a re responsible for trunk and limb musculature posture and balance. THE SPINE 122