Subcostal muscles are the thin muscles found on the inner surface of the posterior thoracic wall bridging two or three intercostal spaces. Together with the intercostal, serratus posterior, levatores costarum, and transversus thoracis muscles they comprise the intrinsic musculature of the chest wall.

The subcostal nerve (anterior division of the twelfth thoracic nerve) is a mixed motor and sensory nerve contributing to the lumbar plexus. It runs along the lower border of the twelfth rib, often gives a communicating branch to the first lumbar nerve, and passes under the lateral lumbocostal arch.

The subcostal nerve provides motor supply to the rectus abdominis, intercostal muscles and anterior abdominal wall muscles. The nerve communicates with the iliohypogastric nerve and gives a motor branch to pyramidalis. [8] We aimed to stimulate the nerve using landmark guidance.