Subcostal artery

The subcostal artery is the last (most inferior) pair of branches arising from the thoracic aorta, located below the twelfth rib. Unlike the intercostal arteries, which run in the intercostal spaces between the ribs, the subcostal artery courses along the inferior border of the twelfth rib, making it distinct in its anatomical position.

Origin and Course

The subcostal artery originates from the posterior aspect of the thoracic (descending) aorta, just below the origin of the eleventh posterior intercostal artery. It passes laterally across the body of the T12 vertebra, posterior to the lateral arcuate ligament (lateral lumbocostal arch) of the diaphragm, and enters the abdominal wall beneath the twelfth rib.

Relations

• It travels posterior to the sympathetic trunk, the pleura, and the kidney.

• On the right side, it passes posterior to the thoracic duct.

• It runs along the inferior border of the twelfth rib, accompanied by the subcostal nerve (T12) and the subcostal vein.

Distribution

The subcostal artery supplies the muscles and skin of the upper abdominal wall and the lower posterolateral thoracic wall. Its terminal branches anastomose with the superior epigastric artery, the lumbar arteries, and the lower posterior intercostal arteries, contributing to the collateral arterial network of the trunk.

Branches

• A posterior (dorsal) branch, which supplies the spinal cord, vertebral column, and back muscles analogous to the dorsal branches of the posterior intercostal arteries.

Clinical Significance

The subcostal artery is an important landmark during procedures involving the retroperitoneal space, thoracolumbar spine surgery, and percutaneous renal access. Injury to this vessel can result in significant hemorrhage. It is also relevant in the context of coarctation of the aorta, where it may participate in collateral circulation.