Nerve · Core

Subcostal nerve

Nervus subcostalis

The nerve of the twelfth thoracic segment, and the odd one out of the chest wall's series. Its eleven neighbours run between two ribs and are called intercostal; this one runs below the last rib with no rib beneath it, which is exactly what its name records. It crosses the back of the abdomen over quadratus lumborum, pierces the transversus abdominis and then travels forward in the same plane the intercostal nerves use, supplying the abdominal wall muscles and a band of skin low on the belly. Its lateral branch descends over the iliac crest to reach skin on the upper outer buttock — the reason a nerve numbered as part of the chest ends up being felt near the hip.