Abdominal Wall, Peritoneum and Intestines - LO 3

3. Describe the neurovascular supply of the abdominal wall.

Innervation

• • The innervation is regular and segmented in the abdominal wall (similar to the thoracic wall) due to no plexus formations of ventral primary rami T7-T12 (thoraco-abdominal nn.; T12 = subcostal n.). The ventral primary ramus of L1 divides into two named nerves: iliohypogastric (superior; just superior to pubic symphysis) & ilio-inguinal (inferior; inguinal canal region). These spinal nerves provide both afferent and efferent innervation. Understanding the dermatome map of this area is of clinical importance, because visceral afferent pain sensation will often be felt in these areas.

Vasculature

• • There are various superficial vasculature that are located in the superficial fascial layer of the abdomen. Of clinical importance, the superficial epigastric v. is a tributary of the femoral v. With portal hypertension, these veins may become distended and anastomose with patent paraumbilical vv. This is known as caput medusae.

  • The main arterial supply and venous drainage of the abdominal wall are the superior & inferior epigastric aa. and vv. These vessels anastomose deep to the rectus abdominis m. Additional supply is derived from intercostal aa.

  • The superior epigastric a. is the continuation of the internal thoracic a. The superior epigastric v. drains into the subclavian v. via the internal thoracic v.

  • The inferior epigastric a. is a branch of the external iliac a. The inferior epigastric v. drains into the external iliac v.