pectoralis major

pec·to·ral·is major (pkt-rls)

n.

A muscle with origin from the clavicle, the anterior surface of the episternum, the sternum, the cartilages of the first to the sixth ribs, and the aponeurosis of the external oblique abdominal muscle; with insertion into the greater tubercle of the humerus, with nerve supply from the anterior thoracic nerve, and whose action adducts the arm and rotates it medially.