9th intercostal nerve

Nervus intercostalis IX

NervousNervesAbdomenLeft and right

View left in 3D View right in 3D

What it is
The ventral ramus of the 9th thoracic nerve. It runs round the chest in the costal groove on the underside of the 9th rib, between the internal and innermost intercostal muscles and below the intercostal vein and artery, then leaves the costal margin to run forward between the internal oblique and transversus abdominis to the rectus sheath.
Function
Motor to the intercostal muscles and the anterior abdominal wall; sensation from a band of skin (lateral and anterior cutaneous branches) and from the parietal pleura and peritoneum.
Size
About 2-3 mm thick; 31-36 cm long
Clinical note
Anterior cutaneous branches can become trapped where they pierce the rectus sheath (ACNES), a cause of chronic abdominal-wall pain.

Nearby nervous structures 10th intercostal nerve, 11th intercostal nerve, Celiac plexus and ganglia, Enteric (myenteric) plexus - marker, L1 spinal nerve, L2 spinal nerve, L3 spinal nerve, L4 dorsal root ganglion, L4 spinal nerve, Superior mesenteric plexus