Muscle
Serratus anterior
Boxer's muscle
High-yield
Long thoracic nerve (C5–C7) injury causes medial scapular winging. "C5, 6, 7 raise your arms to heaven."
Overview
A fan-shaped muscle on the lateral thoracic wall that protracts the scapula and anchors it to the ribs, enabling overhead reach.
Reference facts
- Origin
External surfaces of ribs 1–8 (upper 8–9 ribs)
- Insertion
Anterior (costal) surface of the medial border of the scapula
- Action
Protracts and rotates the scapula for overhead abduction; holds the scapula against the thoracic wall
- Innervation
Long thoracic nerve (C5, C6, C7)
- Blood supply
Lateral thoracic and superior thoracic arteries
Clinical correlation
Long thoracic nerve palsy → winged scapula and inability to raise the arm above horizontal.