Arm and Forearm Muscles (actions)

Modulates action of deltoid, preventing humeral head from sliding upward as arm is abducted; rotates humerus laterally; origin at lateral border and adjacent posterior surface of scapula

Supinates forearm

Prime mover of elbow flexion

Extends elbow; may help to control ulnar movement during pronation

Extends and medially rotates humerus; contributes to arm swinging

Flexes and medially rotates arm; resists deviation of arm from frontal plane during abduction

Adducts and medially rotates humerus; extends the shoulder joint as in pulling on the oars of a rowboat; produces backward swing of arm in such actions as walking or bowling

Extends elbow; long head extends and adducts humerus

Rapid and forceful supination of forearm; synergist in elbow flexion; slight shoulder flexion; tendon of long head stabilizes shoulder by holding humeral head against glenoid cavity

Modulates action of deltoid, preventing humeral head from sliding upward; rotates humerus laterally; origin at infraspinous fossa of scapula