Common iliac artery

The abdominal aorta divides, on the left side of the body of the fourth lumbar vertebra, into the two common iliac arteries.

Each common iliac artery is about 5 cm. in length. They diverge from the termination of the aorta, pass downward and lateralward, and divide, opposite the intervertebral fibrocartilage between the last lumbar vertebra and the sacrum, into two branches, the external iliac and internal iliac arteries; the former supplies the lower extremity; the latter, the viscera and parietes of the pelvis. 

• The right common iliac artery is somewhat longer than the left, and passes more obliquely across the body of the last lumbar vertebra. In front of it are the peritoneum, the small intestines, branches of the sympathetic nerves, and, at its point of division, the ureter. Behind, it is separated from the bodies of the fourth and fifth lumbar vertebræ, and the intervening fibrocartilage, by the terminations of the two common iliac veins and the commencement of the inferior vena cava. Laterally, it is in relation, above, with the inferior vena cava and the right common iliac vein; and, below, with the Psoas major. Medial to it, above, is the left common iliac vein. 

• The left common iliac artery is in relation, in front, with the peritoneum, the small intestines, branches of the sympathetic nerves, and the superior hemorrhoidal artery; and is crossed at its point of bifurcation by the ureter. It rests on the bodies of the fourth and fifth lumbar vertebræ, and the intervening fibrocartilage. The left common iliac vein lies partly medial to, and partly behind the artery; laterally, the artery is in relation with the Psoas major.  

The common iliac arteries give off small branches to the peritoneum, Psoas major, ureters, and the surrounding areolar tissue, and occasionally give origin to the iliolumbar, or accessory renal arteries.