The arterial blood supply to the pelvis and perineum are briefly reviewed. Venous drainage for the most part parallels the arterial vessels. The aorta bifurcates at the level of the fourth lumbar vertebrae into the common iliac arteries (Fig. 8). The arteries run anterior and lateral to the veins at this level (1).
The common iliacs divide into the external and internal iliac arteries at the level of the sacroiliac joint. The external iliac runs along the medial aspect of the iliopsoas and exits the pelvis posterior to the inguinal ligament as the femoral artery.
In pelvic reconstructive surgery, the pertinent branches of the femoral artery are the external pudendal artery to the labial fibrofatty pad and the inferior epigastric artery, which supplies the rectus abdominus muscle. These relationships are important during rotational flap techniques.
The internal iliac artery divides into an anterior and posterior trunk. The posterior trunk gives off the superior gluteal, ascending lumbar, and lateral sacral arteries.
The anterior trunk has seven branches: superior vesical, middle rectal, inferior vesical, uterine, internal pudendal, obturator, and inferior gluteal arteries (1). The course and relationships of several of the branches are highlighted as they pertain to pelvic floor surgery.
Fig. 7. Schematic of urethral and anterior vaginal wall support.
The obturator canal is an opening in the membrane overlying the obturator internus through which the obturator vessels and nerve pass.
The obturator nerve arises from the L2 through S1 nerve roots and exits the pelvis through the obturator canal, where it divides into anterior and posterior divisions to supply the muscles of the adductor compartment.
The obturator canal is nearly 5 cm superolateral to the midpoint of the ischiopubic ramus. This relationship should be kept in mind when passing a device around the ischiopubic ramus for a transobturator procedure (5).
Fig. 8. Pelvic circulation. (From ref. 16.)
The internal pudendal vessels and the pudendal nerve (S2-S4) exit the pelvis through the greater sciatic foramen, wrapping around the ischial spine and SSL laterally (Fig. 9).
Care must be taken to avoid these structures when placing sutures in the SSL. The pudendal nerve and vessels then pass through the lesser sciatic foramen and course alongside the lateral aspect of the ischiorectal fossa to enter the pudendal canal (Alcock’s canal) in the posterior perineum. The pudendal nerve branches into the inferior rectal, perineal, and dorsal (clitoral) nerves (6).
Fig. 9. Nerves of the female perineum. (From ref. 16.)
Understanding lymphatic drainage is mainly significant in treating pelvic malignancy but can be relevant in inflammatory states. The pattern of lymphatic drainage parallels the venous circulation.
The vulvar lymphatic vessels, including the distal urethra and lower third of the vagina, drain into the inguinal lymph nodes. The bladder, proximal urethra, uterus, and upper two-thirds of the vagina drain into the pelvic lymph nodes (obturator, internal, and external iliac).
The ovarian lymphatics follow the gonadal vessels and drain into the para-aortic nodes (3).
Melissa Fischer, MD, Priya Padmanabhan, MD, and Nirit Rosenblum, MD