Shoulder Muscles and Actions

Trapezius Upper (Descending fibers)

Elevates, retracts and upwardly rotates scapula; extends and laterally flexes cervical spine

Trapezius Middle (Transverse fibers)

Retracts scapula

Trapezius Lower (Ascending fibers)

Depresses, retracts and upwardly rotates scapula

Levator Scapulae

Elevates and downwardly rotates scapula; extends, laterally flexes, and ipsilateral rotates cervical spine

Rhomboid Major

Retracts and downwardly rotates scapula

Rhomboid Minor

Retracts and downwardly rotates scapula

Supraspinatus

Abducts and stabilizes arm at GH joint

Infraspinatus

Externally rotates, transversely abducts and stabilizes arm at GH joint

Subscapularis

Internally rotates and stabilizes arm at GH joint

Teres Major

Adducts and internally rotates arm at GH joint

Teres Minor

Externally rotates, transversely abducts and stabilizes arm at GH joint

Triceps Long Head

Extends forearm at elbow joint; assists shoulder extension and adduction

Triceps Lateral Head

Extends forearm at elbow joint

Triceps Medial Head

Extends forearm at elbow joint

Latissimus Dorsi

Adducts, internally rotates, and extends arm at GH joint

Biceps Long Head

Flexes forearm at elbow joint; supinates forearm at radioulnar joints; assists shoulder flexion at GH joint

Biceps Short Head

Flexes forearm at elbow joint; supinates forearm at radioulnar joints; assists shoulder flexion at GH joint

Coracobrachialis

Adducts and flexes arm at GH joint

Brachialis

Flexes forearm at elbow

Serratus Anterior

Protracts scapula and assists in upward rotation

Deltoid Anterior

Flexes and internally rotates arm at GH joint

Deltoid Middle

Abducts arm at GH joint

Deltoid Posterior

Extends, externally rotates and transversely abducts arm at GH joint

Subclavius

stabilizes clavicle

Pectoralis Major (both heads)

Adducts, internally rotates, and transversely adducts arm at GH joint

Pectoralis Minor

Protracts and depresses scapula; assists in downward rotation of scapula