Pectoralis Major

Pectoralis major muscle (lat. musculus pectoralis major) is a muscle on the anterior part of the chest.
 * Origin: It arises from the anterior surface of the sternal part of the clavicle (pars clavicularis), from the sternum (pars sternalis) and from the cartilages of the true ribs (pars abdominalis).
 * Insertion: The muscle is inserted into the greater tubercle of the humerus.
 * Inervation: lateral (C8, Th1) and medial (C5–C7) pectoral nerves (plexus brachialis).
 * Function
 * flexion of humerus;
 * horizontal adduction;
 * inward rotation;
 * secondary inspiratory muscle.