Subcostal artery

At a glance

English

Subcostal artery

Latin (TA2)

Arteria subcostalis

System

Artery

Region

Trunk

Side

Paired, left and right

About the subcostal artery

The subcostal artery takes its name from its position just under the last rib. There is one on each side, and the pair are the final segmental branches given off by the thoracic aorta before it passes through the diaphragm. They belong to the same series as the posterior intercostal arteries, but because there is no rib below the twelfth they run in the body wall rather than in an intercostal space.

From the side of the aorta each vessel passes laterally along the lower edge of the twelfth rib. In this part of its course it has quadratus lumborum behind it and the kidney in front, and it travels alongside the subcostal nerve, the ventral ramus of the twelfth thoracic spinal nerve, with the subcostal vein nearby. Before reaching the rib it crosses the side of the twelfth thoracic vertebral body, passing behind the sympathetic trunk.

At the lateral border of quadratus lumborum the artery pierces the aponeurosis of origin of transversus abdominis. It then runs forwards in the neurovascular plane between transversus abdominis and the internal oblique, the same layer used by the lower intercostal nerves. Here it joins in a network of anastomoses with the superior epigastric artery, the lower posterior intercostal arteries and the lumbar arteries, so the anterolateral abdominal wall receives blood from several directions.

Close to its origin each subcostal artery gives a posterior (dorsal) branch, which behaves like the dorsal branch of an intercostal artery. It passes back to supply the muscles and skin of the back and sends a spinal branch into the vertebral canal. The artery is a landmark during flank approaches to the kidney, where the twelfth rib and its vessels and nerve lie in the operative field.

Course and supply

Arises from

The posterolateral aspect of the lowest part of the thoracic aorta, below the eleventh posterior intercostal artery.

Ends in

Ends in the abdominal wall between transversus abdominis and the internal oblique, linking with the lumbar arteries, the lower posterior intercostals and the superior epigastric artery.

Supplies

Supplies the muscles and skin of the upper posterolateral and anterior abdominal wall, and through its posterior branch the back muscles, skin and spinal canal at the twelfth thoracic level.