The circumflex iliac artery [Latin : circumflexa ilii], smaller than the preceding vessel, arises from the outer side of the iliac artery near Poupart's ligament, and is directed outwards behind that structure to the anterior superior spine of the ilium.

Following the crista of the bone, the artery gives branches to the iliacus muscle, furnishes others, which are distributed to the abdominal muscles, and anastomoses with the ilio-lumbar artery. In its course outwards this artery lies in front of the transversalis fascia, at its junction with the fascia iliaca.

Near the crest of the ilium, this artery gives off a branch which ascends on the fore part of the abdomen between the transversalis and internal oblique muscles; and having supplied those muscles, it anastomoses with the lumbar and epigastric arteries. This branch varies very much in size, and is occasionally represented by small muscular offsets.
Two veins accompany the circumflex iliac artery; these unite below into a single vessel, which crosses over the external iliac artery about an inch above Poupart's ligament, and enters the external iliac vein.

The place of origin of the circumflex iliac artery sometimes deviates from its ordinary position, — the artery arising at a distance not exceeding an inch above Poupart's ligament. Deviations in the opposite direction are more rarely met with ; it has in a few cases been observed to arise below the ligament, and therefore from the femoral artery. The circumflex iliac artery is sometimes represented by two separate branches from the external iliac.

From Quain's anatomy.