innerbody
Diagram

Internal Iliac Vein

The internal iliac veins come from deep in the pelvic region and rise to the lower portion of the abdomen, where they join with the right and left external iliac veins and form the common iliac veins. These, in turn, merge to produce the inferior vena cava at the level of the fifth lumbar vertebra. In the pelvic region, blood is carried away from organs of the reproductive, urinary, and digestive systems Continue Scrolling To Read More Below...

Continued From Above... by vessels leading to the internal iliac veins. These veins have many interconnections that form a network (called plexuses) in the region of the rectum, urinary bladder, and prostate gland (in the male) or uterus and vagina (in the female).