Serratus Anterior
Shoulder & Arm
The 'boxer's muscle' — essential for throwing punches. Damage to the long thoracic nerve causes 'winged scapula.'
Function
Protracts scapula, rotates scapula upward, holds scapula against thoracic wall
Origin
External surfaces of ribs 1-8/9
Insertion
Costal surface of medial border of scapula
Innervation
Long thoracic nerve (C5-C7)