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.

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pectoralis major

[pek′tərā′lis, pek′tərəlis′]

Etymology: L, pectus, breast

a large muscle of the upper chest wall that acts on the joint of the shoulder. Thick and fan-shaped, it arises from the clavicle, the sternum, the cartilages of the second to the sixth ribs, and the aponeurosis of the obliquus externus abdominis. It serves to flex, adduct, and medially rotate the arm in the shoulder joint.