The iliohypogastric nerve (also known as the iliopubic nerve) is a mixed nerve that originates from the lumbar plexus and innervates the skin in the inguinal, pubical and gluteal regions, as well as abdominal muscles. 

The nerve originates from the ventral rami of the twelfth thoracic (T12) and first lumbar (L1) nerves. It emerges from the lateral side of the psoas major, descends obliquely and above the iliac crest. Then it penetrates the transversus abdominus muscle, runs between it and the internal abdominal oblique, and further between the internal abdominal oblique and external abdominal oblique muscles.

On its course, the iliohypogastric nerve gives off two cutaneous branches (anterior and lateral) to innervate the skin, and several motor branches to the abdominal muscles.

• The anterior cutaneous branch pierces the aponeurosis of the external abdominal oblique muscle and innervates the skin in the inguinal and pubical regions.
• The lateral cutaneous branch innervates the skin below the iliac crest and in the gluteal region.
• The motor branches of the iliohypogastric nerve innervate the transversus abdominis, as well as the external and internal abdominal oblique muscles.