Serratus anterior

Musculus serratus anterior

// Structure & location

The muscle arises by separate slips from the upper ribs, hence the name (serratus = saw-toothed). It runs back between the rib cage and the shoulder blade and inserts on the inner edge of the scapula. In lean, trained people it is visible as a jagged pattern below the armpit.

// Function

It pulls the shoulder blade forward around the rib cage (protraction), as in a punch or a push. It also rotates it upwards, which is needed to raise the arm overhead, and presses it flat against the rib cage.

// For training & sport

• In a push-up plus you push the shoulders a bit further away from the floor at the top of each rep.
• Overhead and landmine presses challenge it while the shoulder blade rotates up.

// Good to know

If the muscle fails, for example after an injury to its nerve, the shoulder blade sticks out from the back like a wing (scapular winging). Because of its role in punching it is also called the boxer's muscle.

// Sources

• LehrbuchOpenStax – Anatomy and Physiology, 11.5 Muscles of the Pectoral Girdle and Upper Limbs ↗cite

// More from the atlas: Muscles