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 region, and the abdominal muscles. 

It originates from the ventral rami of the twelfth thoracic (T12) and first lumbar (L1) nerves. 

The iliohypogastric nerve emerges from the lateral side of the psoas major, descends obliquely and above the iliac crest. Then it penetrates the transverse abdominal muscle, runs between it and the abdominal internal oblique muscle, and further between the abdominal internal oblique and external oblique muscles.

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

• Anterior cutaneous branch - pierces the aponeurosis of the abdominal external oblique muscle and innervates the skin in the inguinal and pubical regions. 

• Lateral cutaneous branch - innervates the skin below the iliac crest and in the gluteal region.

• Motor branches - innervate the transverse abdominis, as well as the external and internal oblique muscles.