Pectoralis Major

Origin: Clavicle, Sternum, Ribs 1-6, and External Oblique muscle (via an aponeurosis)

Insertion: Humerus (Intertubercular groove and crest of greater tubercle)

Action: Shoulder Adduction, Medial Rotation, Flexion of an extended arm, Extension of a flexed arm, Horizonal Adduction