General Anatomic Descriptions

The abdominal aorta divides into the common iliac arteries at approximately the level of L4. The middle sacral artery, usually a very small vessel, arises from the posterior surface of the aortic bifurcation and extends inferiorly along the anterior surface of the sacrum, in the midline, to the distal tip of the coccyx. The length of the common iliac artery is variable. Each common iliac artery divides into an external iliac artery and internal iliac artery (Fig. 73-1).

FIGURE 73-1 Schematic drawing of the pelvic arterial vessels.

(Adapted from Uflacker R. Atlas of Vascular Anatomy: An Angiographic Approach, 2nd ed. Philadelphia, Lippincott Williams & Wilkins, 2006.)

The external iliac artery has only two branches, the deep circumflex iliac and inferior epigastric arteries. Both arise approximately at the point where the inguinal ligament crosses anterior to the external iliac artery, and both serve as markers on arteriograms for the junction of the external iliac artery and common femoral artery. Some experts consider the inferior epigastric artery to arise from the proximal femoral artery. The deep circumflex iliac artery extends superolaterally from its origin on the lateral aspect of the external iliac artery, and supplies the pelvic side wall. It anastomoses with the iliolumbar and superior gluteal arteries, branches of the internal iliac artery, and with the ascending branch of the lateral circumflex femoral artery, a branch of the profunda femoral artery. The inferior epigastric artery arises from the medial aspect of the external iliac artery and dips inferiorly and medially before turning superiorly to course deep to the rectus abdominis muscle in the anterior abdominal wall (Fig. 73-2). Superiorly, it anastomoses with the superior epigastric artery, a branch of the internal thoracic artery.

FIGURE 73-2 A, Schematic drawing of the external iliac, common femoral, superficial femoral arteries, and branch vessels. B, Angiogram of the right external and common iliac arteries and branch vessels (contralateral oblique view).

(A, adapted from Uflacker R. Anatomy Atlas of Vascular Anatomy: An Angiographic Approach, 2nd ed. Philadelphia, Lippincott Williams & Wilkins, 2006.)

The internal iliac artery has anterior and posterior divisions. Branches of the anterior division primarily supply the pelvic viscera, whereas branches of the posterior division supply pelvic bones and muscles (Fig. 73-3A).

FIGURE 73-3 A, Angiogram of the right internal iliac artery, with anterior and posterior divisions. B, Angiogram of the posterior division of the left internal iliac artery.

Typically, the three branches of the posterior division are the iliolumbar artery, lateral sacral artery, and superior gluteal artery (see Fig. 73-3B). The iliolumbar artery extends laterally and superiorly to divide into two branches that supply the iliacus muscle and ilium (iliac branch) and the psoas major and quadratus lumborum muscles (lumbar branch). The lateral sacral artery extends medially and then superiorly to supply the spinal meninges and the roots of the sacral nerves. The superior gluteal artery, the largest branch of the internal iliac artery, extends laterally, passes above the piriformis muscle through the greater sciatic foramen as it leaves the pelvis posteriorly, and supplies the gluteal muscles, overlying soft tissues and skin. These posterior division branches may, on occasion, arise from the anterior division or from trunks formed by various combinations of internal iliac artery branches (see later).

The anterior division of the internal iliac artery divides into a number of named arteries. As with the posterior division branches, the anterior division vessels may occasionally arise from the posterior division or from trunks formed by various combinations of internal iliac artery branches.

The three principal branches of the anterior division are the obturator artery, inferior gluteal artery, and internal pudendal artery (Fig. 73-4A). The obturator artery courses along the pelvic brim, bifurcates above the obturator notch, and passes laterally through the obturator foramen to supply muscles of the thigh and ligament of the femoral head. It is usually the most lateral of the anterior division branches. A distal branch of the obturator artery anastomoses with the medial circumflex femoral artery, a branch of the profunda femoral artery. The inferior gluteal artery has a variable intrapelvic course, typically concave laterally. It courses inferiorly, anterior to the piriformis muscle and sacral plexus, extends laterally, and exits the bony pelvis via the greater sciatic notch. It supplies the muscles and skin of the buttock and posterior surface of the thigh. In rare cases, it gives rise to a persistent sciatic artery (see later). The internal pudendal artery courses inferiorly along the anterior surface of the piriformis muscle, lateral to the inferior gluteal artery, and enters the ischiorectal fossa through the lesser sciatic foramen. It has numerous small named branches. It supplies the perineum and external genitalia.

FIGURE 73-4 A, Angiogram of the anterior division of the left internal iliac artery. B, Angiogram of the left uterine artery, with cervicovaginal branch.

The remaining branches of the anterior division are less prominent (see Fig. 73-1). The superior vesical artery has an inferomedial course until it reaches the lateral aspect of the bladder, at which point it courses along the superior surface of the bladder; its position varies depending on the degree of bladder distention. It supplies up to 80% of the bladder, as well as the distal ureters and, in males, the ductus deferens. The inferior vesical artery has an inferomedial course whose position is not dependent on the degree of bladder distention. It is a small vessel, difficult to appreciate angiographically, which supplies the inferolateral surface of the bladder, the trigone and, in males, the seminal vesicles and prostate. In females, the analogous vessel is sometimes termed the vaginal artery. It supplies the vagina, posteroinferior portions of the bladder, and pelvic part of the urethra. The vaginal artery may be a single vessel or two or three separate arteries. The inferior vesical artery often forms a common trunk with the middle rectal artery. The middle rectal artery may arise from the anterior division, but is frequently a branch of another artery in the internal iliac artery distribution. This small vessel is the most posterior of the anterior division vessels, and descends inferomedially to the ipsilateral side of the middle portion of the rectum. It anastomoses with the superior and inferior rectal arteries to supply the rectum and sometimes inferior vesical–vaginal artery territory. The uterine artery has a characteristic U-shaped course; it descends, turns medially to course along the broad ligament, and then ascends in the parametrium along the lateral border of the uterus. The cervicovaginal artery, which supplies the cervix and vagina, arises near the junction of the medial and ascending portions. The ascending portion is typically convoluted and gives off numerous convoluted branches that extend medially (see Fig. 73-4B). In postpartum women, the uterine artery may extend superiorly, without demonstrating the U-shaped course typical of the nongravid uterus.

Other arteries arise outside the pelvis but terminate within it. These are the superior rectal artery, which is the continuation of the inferior mesenteric artery in the pelvis, and the gonadal arteries—internal spermatic (testicular) arteries in the male and ovarian arteries in the female. The gonadal arteries arise from the abdominal aorta at the L2 or L3 level and accompany the gonadal veins into the pelvis.

Detailed Description of Specific Areas

Normal Variants

The common iliac arteries are absent in fewer than 1% of individuals. In this case, the aorta divides into four branches, the internal and external iliac arteries bilaterally.

Variations of the internal iliac artery and its branches are common. Typically, the internal iliac artery divides into two branches, as noted earlier. However, this arrangement is seen in approximately 60% of cases, and the remaining 40% demonstrate one (10%), three (20%), or four or more (10%) principal trunks. The sequence of branch origins and trunk formation is extremely variable. The obturator artery may arise from the external iliac artery or the inferior epigastric artery. A persistent sciatic artery, which arises from the inferior gluteal artery, is a rare but clinically important variant (Fig. 73-5). Because it is often symptomatic, it is discussed separately later.

FIGURE 73-5 Schematic drawing of persistent sciatic artery.

Differential Considerations

Arterial bypass grafts for infrarenal aortic or iliac artery disease originate from the axillary artery or the infrarenal aorta and insert in the external iliac, common femoral, or profunda femoral arteries, depending on the site(s) of disease (Fig. 73-6). Common femoral artery to common femoral artery grafting can be performed for unilateral common iliac or external iliac artery disease (Fig. 73-7). Lower extremity atherosclerosis requiring surgical bypass can be treated with a graft originating at the common femoral artery and terminating at the popliteal artery (ideally, superior to the knee joint), posterior tibial artery, or anterior tibial artery, as required (Fig. 73-8).

FIGURE 73-6 CTA scan showing axillary-femoral (Ax-fem) bypass graft.

FIGURE 73-7 CTA scan showing femoral-femoral (Fem-fem) bypass graft.

FIGURE 73-8 CTA scan showing femoral-popliteal (Fem-pop) bypass graft.

In the pelvis, a persistent sciatic artery can be clinically important. The sciatic artery normally involutes by the 22-mm embryo stage, with remnants persisting as the proximal portion of the inferior gluteal artery, popliteal artery, and peroneal artery.¹ Rarely, the sciatic artery persists, either because of failure of development of the superficial femoral artery or failure of regression of the sciatic artery.² A persistent sciatic artery is the continuation of the internal iliac artery (see Fig. 73-5), arising from the anterior division distal to the origin of the internal pudendal artery. It follows the course of the inferior gluteal artery through the greater sciatic foramen, where it may accompany the posterior cutaneous nerve or sciatic nerve. It continues inferiorly along the posterior aspect of the adductor magnus and then passes through the popliteal fossa to form the popliteal artery and supply the leg and foot.¹

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