The common iliac vein is formed by the union of the external iliac and internal iliac veins, opposite the sacroiliac articulation at the inlet of the pelvis. The right common iliac vein is the shorter of the two, and holds a more vertical course than the left. It lies behind, and then to the posterolateral side of the right common iliac artery. The left common iliac vein runs a more oblique course. It lies on the medial side of the left common iliac artery and then crosses beneath the right common iliac artery to join the right common iliac vein, in front of the right side of the body of the fifth lumbar vertebra, to form the inferior vena cava. It is crossed by the sigmoid mesocolon and the superior rectal vessels.

Vena iliaca communis

Veine iliaque commune