Lumbar arteries

At a glance

English

Lumbar arteries

Latin (TA2)

Arteriae lumbales

System

Artery

Region

Trunk

Side

Paired, left and right

About the lumbar arteries

The lumbar arteries are the abdominal counterparts of the posterior intercostal arteries of the chest. There are usually four on each side, springing in pairs from the back of the abdominal aorta at the levels of the first to fourth lumbar vertebral bodies. A small fifth pair, when present, comes from the median sacral artery; otherwise the lumbar branch of the iliolumbar artery takes over that level.

Each artery curves backwards and outwards around the side of its vertebral body, passing behind the sympathetic trunk. Those on the right also run behind the inferior vena cava; on both sides the highest two pass behind the crus of the diaphragm. All of them go under the fibrous arches from which psoas major takes origin, then behind psoas and the lumbar plexus, to reach the gaps between neighbouring transverse processes. They then cross quadratus lumborum, the upper three usually behind it and the lowest usually in front.

Between the transverse processes each artery gives a dorsal branch. This runs back to supply the deep muscles and skin of the back, and sends a spinal branch through the intervertebral foramen to the vertebra, the meninges and the nerve roots or cauda equina. The main stem continues forwards: at the lateral edge of quadratus lumborum it pierces the aponeurosis of transversus abdominis and runs between that muscle and the internal oblique, like an intercostal artery in the abdominal wall.

In the wall they join the lower posterior intercostal and subcostal arteries above and the iliolumbar, deep circumflex iliac and inferior epigastric arteries below. These links give collateral flow round a blocked lower aorta. The lumbar arteries can bleed into an aortic aneurysm sac after a stent graft has been placed (a type II endoleak), and they are at risk in surgery on the lumbar spine from the front or side.

Course and supply

Arises from

Usually four pairs from the posterior surface of the abdominal aorta opposite the first to fourth lumbar vertebrae; a small fifth pair may come from the median sacral artery.

Ends in

Each divides into a dorsal branch to the back and a spinal branch to the vertebral canal, and continues forwards between transversus abdominis and the internal oblique.

Supplies

Supplies the lumbar vertebrae, spinal cord coverings and nerve roots, the muscles and skin of the lower back, psoas major, quadratus lumborum and the posterolateral abdominal wall.