The Common Iliac Veins (Fig. )

These (V. iliacæ communes) are two very large but short trunks which result from the union of the internal and external iliac veins of each side at the sacro-iliac articulation. The left one is the longer and crosses obliquely over the terminal part of the aorta. The chief tributaries of each are as follows:

1. The last lumbar vein.

2. The circumflex iliac veins (Vv. circumflexæ ilium profundæ) are the two satellites of each corresponding artery, on either side of which they are placed. They may open directly into the posterior vena cava or into the external iliac vein.

3. The ilio-lumbar vein (V. iliolumbalis) may open into the common iliac, the external iliac, or the internal iliac vein.