Iliohypogastric nerve

At a glance

English

Iliohypogastric nerve

Latin (TA2)

Nervus iliohypogastricus

System

Nerve

Region

Abdomen

Side

Paired, left and right

About the iliohypogastric nerve

The iliohypogastric nerve is the first branch of the lumbar plexus. Its fibres come mainly from the upper part of the anterior ramus of the first lumbar nerve, with a contribution from the twelfth thoracic nerve carried across by the subcostal nerve. It runs a course much like an intercostal nerve, wrapping around the trunk between the layers of the abdominal wall, and is accompanied a little lower down by the ilio-inguinal nerve.

It appears at the upper part of the lateral border of psoas major and crosses the front of quadratus lumborum behind the kidney. Just above the iliac crest it pierces transversus abdominis and then divides, in the plane between transversus and internal oblique, into two branches. The lateral cutaneous (iliac) branch pierces both oblique muscles just above the crest and descends to the skin of the upper lateral buttock, behind the territory of the subcostal nerve; when one of these two is large, the other tends to be small. The anterior cutaneous (hypogastric) branch carries on forwards between the two deeper muscles, pierces internal oblique and then the external oblique aponeurosis roughly 2.5 cm above the superficial inguinal ring, and spreads in the skin above the pubis.

Along its course the nerve exchanges fibres with both the subcostal and ilio-inguinal nerves. It is absent in a sizeable minority of people, perhaps up to one in five, and its fibres then travel in a neighbouring nerve, usually the ilio-inguinal.

The nerve is most often injured during operations. Its lateral branch lies right over the front of the iliac crest and is the nerve most at risk when bone graft is taken from the anterior crest, leaving a numb or painful patch on the hip. Where it pierces the oblique muscles it can be caught by sutures or scar after lower abdominal incisions. It is commonly blocked together with the ilio-inguinal nerve for pain relief after groin surgery.

Course and supply

Arises from

The anterior ramus of L1, joined by T12 fibres brought by the subcostal nerve; it emerges at the upper lateral border of psoas major.

Ends in

Divides between transversus abdominis and internal oblique into a lateral cutaneous branch to the buttock and an anterior cutaneous branch to the suprapubic skin.

Supplies

Motor to internal oblique and transversus abdominis; sensory to the skin of the upper lateral gluteal region and the hypogastric (suprapubic) region.