Pelvic blood vessels

The pelvic cavity contains the organs of reproduction, urinary bladder, pelvic colon, rectum and numerous muscles. Its arterial supply is largely via the internal iliac artery, with some smaller arteries providing additional supply.

The pelvis is a bony case that houses gastrointestinal and urogenital viscera, and provides support for locomotion. There is a vast neurovascular network traversing this region to supply the region with oxygenated blood and to convey neuronal impulses between the region and the central nervous system. While the general vasculature and neuronal networks are common in both males and females, there are some differences based on sexual dichotomy.

The arteries of the pelvis are derived from the abdominal aorta, which bifurcates into a left and right common iliac artery on the left hand side of the fourth lumbar vertebra. Similarly, the common iliac veins, which are formed from venous tributaries of the region, unite at the fifth lumbar vertebra to form the inferior vena cava.

Internal iliac artery is one of the bifurcations of the common iliac artery. The bifurcation occurs over the sacroiliac articulation. It measures about 2 cm. Ureter lies anteriorly and the internal iliac vein, posteriorly. It soon divides into anterior and posterior divisions. Only the anterior division supplies the pelvic viscera. 

The uterine artery arises either directly from the internal iliac artery or in common with the obliterated umbilical artery. It runs downwards and forwards along the lateral pelvic wall almost in the same direction as the ureter until it reaches the base of the broad ligament. It then turns medially and crosses the ureter anteriorly from above and at right angle to it; about 1.5-2 cm lateral to, at the level of internal os. On reaching the side of the uterus, it runs upwards and takes a spiral course along the lateral uterine wall between the layers of broad ligament. It ultimately anastomoses end on with the tubal branch of the ovarian artery in the mesosalpinx.

Segmental arcuate arteries are the branches from the ascending part. These pierce about one- third of the myometrium and then divide into anterior and posterior branches. These anastomose with the corresponding branches of the opposite side in the midline. Thus, the middle of the uterus is comparatively avascular. From the arcuate arteries, a series of radial arteries arise almost at right angles, which stretch through the entire length of the myometrium.

The vaginal artery arises either from the uterine artery or directly from the anterior division of the internal iliac artery. It is in relation to the lateral fornix and then runs down along the lateral wall of the vagina. Numerous transverse branches are sent off anteriorly and posteriorly, which anastomose with the similar branches of the other side to form azygos arteries of the vagina-one anterior and one posterior.

Internal Pudendal Artery is one of the parietal branches of the anterior division of the internal iliac artery. It leaves the pelvic cavity along with its vein and pudendal nerve through the greater sciatic foramen and re-enters the ischiorectal fossa to lie in the pudendal canal (Alcock's canal) after winding round the ischial spine. Here, it gives off inferior rectal artery. Thereafter, it sends numerous branches to supply the perineal and vulvar structures, including the vestibular bulb and clitoris. The terminal branches of the artery anastomose with superficial and deep pudendal arteries, branches of the femoral artery. This will help in maintaining the blood supply of the bladder when the vesical branch of the internal iliac artery is ligated.

Ovarian artery arises from the front of the aorta, a little below the renal artery. It enters the pelvic cavity after crossing the external iliac vessels. It then runs medially along the infundibulopelvic ligament to enter the mesovarium. As it enters the hilum of the ovary, it breaks up into numerous branches to supply the organ.

Superior rectal artery is a continuation of the inferior mesenteric artery and descends down to the base of pelvic mesocolon. It then divides into two and each courses down on either side of the rectum to supply it by numerous branches.

The ovarian veins on each side begin from the pampini-form plexus, which lies in between the layers of broad ligament near the mesovarium. Beyond the infundibu-lopelvic ligament, there are two ovarian veins on each side, which ascend up along the course of the corresponding artery. Higher up, the veins become one and ultimately drains into left renal vein on the left side and inferior vena cava on the right side. Venous drainage from the uterine, vaginal, and vesical plexuses chiefly drain into internal iliac vein. Venous drainage from the rectal plexus drains via superior rectal vein into the inferior mesenteric vein. The middle and inferior rectal veins drain into the internal pudendal vein and thence to the internal iliac vein.

Published : Dec 12 2023