These nerves are the ventral rami of the thoracic spinal nerves T7-T11 and subcostal nerves T12. They supply the anterolateral muscles and overlying skin. These nerves are supplemented by the anterior terminal branches of the subcostal nerves and by a branch of the iliohypogastric nerve (L1) of the lumbar plexus after passing through the muscles, they are sensory nerves of the skin.