Nerve · Core

Iliohypogastric nerve

Nervus iliohypogastricus

The highest branch of the lumbar plexus, and the one that behaves most like a thoracic nerve. It leaves the upper lateral border of psoas major, crosses quadratus lumborum behind the kidney, then pierces transversus abdominis above the iliac crest and travels forward between that muscle and internal oblique — the same plane the lower intercostal nerves use. On the way it supplies the lower fibres of both muscles and gives a lateral branch to the skin over the upper buttock, ending as an anterior branch that pierces the aponeurosis just above the pubis. It is one of the two nerves — the ilioinguinal is the other — that carry the motor supply to the lowest fibres of the abdominal wall, near the groin.