Situated on the inner aspect of the arm. It is broad above, and becomes narrower as it descends. In front it presents a thick fleshy mass, while its posterior part is flat and thin. This muscle forms the prominence so conspicuous in front of the breast.
Insertion.-Into the ridge in front of the humerus bounding the musculo-spiral groove, and into the fascia covering the inner surface of the arm.
By some anatomists this muscle is divided into two parts, termed the anterior and posterior superficial pectoral.