Subcostal artery

The subcostal artery (Latin: arteria subcostalis) is a paired blood vessel that travels below the last pair of ribs. The subcostal arteries are the lowest parietal branches of the thoracic aorta. They mainly supply the flat abdominal muscles, such as the external obliques, internal obliques, and transversus abdominis.

Each subcostal artery passes along the inferior border of the 12th rib behind the kidney and in front of the quadratus lumborum muscle. On its course, it is accompanied by the 12th thoracic spinal nerve. The subcostal artery then pierces the aponeurosis of the transversus abdominis muscle.

The artery passes forward between the transversus abdominis and the internal oblique muscles, where it anastomoses with several vessels, including the superior epigastric, lower intercostal, and lumbar arteries. Each subcostal artery gives off a posterior branch that has a similar course as the posterior branches of the posterior intercostal arteries. It also participates in supplying the spinal cord and soft tissue structures of the back.