Pelvic Blood Vessels and Lymphatics Anatomy
The pelvic walls and floor and the pelvic organs receive most of their arterial supply from branches of the internal iliac artery, which also provides branches to the perineum and lower limb. The rectum, however, receives its principal supply from the superior rectal artery (pp 182, 218 & 238), while the posterior wall of the pelvis is supplied by the median sacral artery (Fig. 5.31). The ovaries are supplied by the ovarian branches of the abdominal aorta (p. 190).
The internal iliac artery arises in front of the sacroiliac joint as one of the terminal branches of the common iliac artery (Fig. 5.32). The internal iliac artery runs downwards and backwards on the lateral pelvic wall, giving rise to visceral and parietal branches.
Before birth, the largest branch of the internal iliac artery is the umbilical artery, which conveys blood to the placenta. In the adult, only its proximal part is patent. It runs forwards, adjacent to the bladder, giving one or more superior vesical branches (Fig. 5.32) and a slender branch to the ductus deferens. Distally, the vessel becomes a fibrous cord, the occluded part of the umbilical artery or medial umbilical ligament, which continues through the extraperitoneal tissues of the anterior abdominal wall to the umbilicus (Fig. 4.30). The inferior vesical artery occurs only in the male and supplies the lower part of the bladder, the prostate, the seminal vesicle and the pelvic ureter. The uterine artery runs medially in the root of the broad ligament, crosses above the ureter (Fig. 5.13) and supplies the vagina and the uterine cervix, body and tube. The artery follows the lateral border of the body of the uterus, then runs laterally in the broad ligament, close to the uterine tube, and terminates by anastomosing with the ovarian artery.
The vagina is supplied by branches of the uterine artery together with one or two small vaginal arteries from the internal iliac artery.
The middle rectal artery (Fig. 5.32) supplies the muscle coat of the rectum and in the male, may give additional branches to the prostate and seminal vesicles.
The obturator artery runs downwards and forwards, with the corresponding vein and nerve, to enter the obturator canal. It supplies the proximal part of the medial compartment of the thigh and the hip joint (Figs 5.28 & 5.32). Occasionally, the obturator artery takes origin from the inferior epigastric artery and descends into the pelvis to reach the obturator canal. Such a vessel, an accessory or abnormal obturator artery (Fig. 5.30), passes close to the femoral ring. In the latter case, it may be damaged during femoral hernia operations (Figs 4.23 & 5.30, femoral ring).
The superior and inferior gluteal arteries pass through the greater sciatic foramen into the buttock, the superior artery running above piriformis (Fig. 5.31) and the inferior below (p. 271).
The internal pudendal artery provides the principal arterial supply to the perineum. The artery passes through the greater sciatic foramen into the gluteal region, curves round the ischial spine and then passes forwards through the lesser sciatic foramen into the perineum (p. 241).
The iliolumbar artery ascends the posterior abdominal wall to anastomose with the lower lumbar arteries.
The lateral sacral artery (Fig. 5.31) supplies the posterior wall of the pelvis and anastomoses with the median sacral artery.
Internal iliac vein and tributaries
The branches of the internal iliac artery are accompanied by veins that drain the buttock and perineum, the pelvic walls and most of the pelvic organs. These veins unite to form the internal iliac vein (Fig. 5.33), which ascends on the lateral pelvic wall posterior to the artery. The vein terminates by joining the external iliac vein to form the common iliac vein.
Most of the veins emerging from the pelvic organs anastomose freely, forming extensive venous plexuses (the vesical, prostatic, uterine and vaginal plexuses). While most blood from these plex- uses passes into the internal iliac vein, some enters either the superior rectal vein via portacaval anastomoses or the vertebral venous plexus via the anterior sacral foramina. Prostatic carcinoma can spread via these venous plexuses to the sacral and lumbar vertebrae.
Lymph from the pelvis is drained by lymphatic vessels that accompany the arteries. Most of the lymph drains into nodes adjacent to the internal iliac artery and then into efferent vessels that pass to the common iliac nodes (p. 196). However, lymphatic vessels from the ovaries and the rectum pass directly to the aortic nodes, and some vessels from the body of the uterus accompany the round ligament through the inguinal canal to terminate in the superficial inguinal nodes.