Iliolumbar artery

Course

The iliolumbar artery is usually the first branch of the posterior division of the internal iliac artery. From its origin, it arches backward and ascends laterally out of the pelvic inlet toward the iliac fossa. It travels anterior to the sacroiliac joint and lumbosacral nerve trunk, passing behind the external iliac vessels to reach the medial border of the psoas major muscle.

Just posterior to the medial border of the psoas major muscle, the iliolumbar artery divides into lumbar and iliac branches.

Branches and supply

The iliolumbar artery has two main branches that contribute to the arterial supply of the posterior abdominal wall muscles and other structures in that region;

• The lumbar branch supplies the psoas major and quadratus lumborum muscles. It forms an anastomosis with the fourth lumbar artery. Additionally, it gives rise to a small spinal branch that travels through the intervertebral foramen between the fifth lumbar vertebra (L5) and the first sacral vertebra (S1). This branch supplies the cauda equina.
• The iliac branch travels laterally into the iliac fossa to supply the iliacus muscle and the iliac bone. This branch also forms anastomoses with iliac branches of the obturator artery, the deep circumflex iliac artery, the lateral circumflex femoral artery as well as the superior gluteal artery. Through these anastomoses, the iliac branch contributes to the arterial supply of the gluteal and abdominal wall muscles.

Anatomical variations

Although the iliolumbar artery typically arises from the posterior division of the internal iliac artery, its origin is variable. It can commonly arise directly from the main trunk of the internal iliac artery. It has also been reported to arise less commonly from the superior gluteal artery, common iliac artery or lateral sacral artery.