The muscles of the urogenital diaphragm anteriorly reinforce the pelvic diaphragm and are intimately related to the vagina and the urethra. They are enclosed between the inferior and superior fascia of the urogenital diaphragm. The muscles include the deep transverse perineal and sphincter urethrae (Table 5.1).
Blood Vessels The pelvic blood vessels supply genital structures as well as the following:  Urinary and gastrointestinal tracts  Muscles of the abdominal wall, pelvic ﬂoor and perineum, buttocks, and upper thighs  Fasciae, other connective tissue, and bones  Skin and other superficial structures
Classically, vessels supplying organs are known as visceral vessels and those supplying supporting structures are called parietal vessels.
Major Blood Vessels The course of the major vessels supplying the pelvis is illustrated in Figure 5.5; their origin, course, branches, and venous drainage are presented in Table 5.2. In general, the venous system draining the pelvis closely follows the arterial supply and is named accordingly. Not infrequently, a vein draining a particular area may form a plexus with multiple channels. Venous systems, which are paired, mirror each other in their drainage patterns, with the notable exception of the ovarian veins. Unusual features of venous drainage are also listed in Table 5.2.
Figure 5.5 The blood supply to the pelvis. A: The sagittal view of the pelvis without the viscera. B: The blood supply to one pelvic viscera.
Table 5.2 The Major Blood Vessels of the Pelvis
Ovarian Arises from ventral Crosses over common iliac vessels; in To ovaries, fallopian tubes, broad ligament; often Right side drains into the surface of aorta just proximity to ureter over much of its small branches to ureter inferior vena cava; left below the origin of the course, crosses over ureter while drains into the left renal vessels superficial to the psoas muscle and renal vein runs just lateral to the ureter when entering the pelvis as part of the infundibulopelvic ligament
Inferior mesenteric Unpaired left-sided IMA and its branches pass over the left 1. Left colic—originates above pelvic brim; Inferior mesenteric vein artery (IMA) retroperitoneal artery psoas muscle and common iliac supplies left transverse colon, splenicﬂexure, empties into the arising from the aorta vessels; IMA courses anterior to the descending colon splenic vein 2–5 cm proximal to its ureter and ovarian vessels above the 2. Sigmoid—several branches; supply sigmoid 3. Superior rectal (hemorrhoidal)—divides into two terminal branches to supply rectum
Common iliac Terminal division of the Oblique and lateral course, about 1. External iliac Lie posterior and slightly artery aorta at fourth lumbar 5 cm in length medial to arteries; drain 2. Internal iliac
External iliac Lateral bifurcation of Along the medial border of the psoas femoral artery common iliac, begins muscle and lateral pelvic side wall; opposite the becomes femoral artery after passing lumbosacral joint under the inguinal ligament to supply lower extremity 1. Superficial epigastric—supplies skin and subcutaneous tissue of lower anterior abdominal wall 2. External pudendal—supplies skin and subcutaneous tissue of mons pubis and anterior vulva 3. Superficial circumﬂex iliac—suppliesskin/subcutaneous tissues of theﬂank 4. Inferior epigastric—supplies musculofascial layer of lower anterior abdominal wall 5. Deep circumﬂex iliac—suppliesmusculofascial layer of lower abdominal wall
Lie posterior and then medial to the artery as it enters the anterior thigh; drain into common iliac veins