What nerves innervate the anterior abdominal wall?

The anterior abdominal wall is innervated by spinal nerves from T7 to L1. These include the lower intercostal nerves (T7–T11), subcostal nerve (T12), and the iliohypogastric and ilioinguinal nerves (both L1). They provide motor and sensory functions to muscles and skin.

What is the function of the intercostal nerves in the abdominal wall?

The lower intercostal nerves (T7–T11) supply motor innervation to the rectus abdominis muscle and sensory innervation to the overlying skin. They travel in the neurovascular plane between internal oblique and transversus abdominis muscles.

How do the iliohypogastric and ilioinguinal nerves differ?

Both are derived from L1, but they have distinct paths and functions. The iliohypogastric nerve supplies internal oblique, transversus abdominis, and skin of the gluteal region, and does not enter the rectus sheath. The ilioinguinal nerve enters the inguinal canal, supplies skin on the medial thigh and scrotum/labium majus, and also does not enter the rectus sheath.

Why are the ilioinguinal and iliohypogastric nerves important in surgery?

These nerves are at risk during lower abdominal surgeries, such as hernia repairs. Injury can lead to numbness or weakness in the lower abdominal wall, so careful surgical technique is essential to avoid damage.

What role does the subcostal nerve play?

The subcostal nerve (T12) supplies the pyramidalis muscle and overlying skin. It also gives a lateral cutaneous branch to the gluteal region, making it relevant for procedures involving the lower back or hip.

How is pain referred from the abdomen related to these nerves?

Visceral pain, such as from appendicitis, can be referred to dermatomes supplied by these nerves. For example, pain may be felt in the umbilical region due to innervation by the T10 nerve, illustrating segmental pain referral patterns.

Abdominal Wall Nerves – T7–L1 Innervation