ABSTRACT

The iliohypogastric nerve originates from the L1 nerve root with contributions from the T12 nerve root. The nerve passes between the bundles of the psoas muscle to arch over the quadratus lumborum muscle to run superiorly and laterally behind the kidney. It pierces the aponeurosis at the origin of the transversus abdominis muscle and internal oblique muscle, innervates these muscles, and turns inferiorly to run between the internal and external oblique muscles above the inguinal ligament. In this area, the lateral cutaneous branch separates from the main trunk to pierce the internal and external oblique muscles above the middle of the iliac crest before innervating the area of skin overlying the gluteus medius and tensor fasciae latae muscles. It terminates near the rectus abdominus muscle with one final branch, the anterior cutaneous nerve. This sensory branch tracts medially above the annulus inguinalis subcutaneous, pierces the anterior sheath of the rectus abdominus muscle, and innervates the skin above the inguinal ligament and symphysis.