NCIt definition : Muscles of the upper chest. The term may refer to one of two muscles, the pectoralis
major and pectoralis minor. The former is a thick muscle in the anterior portion of
the chest. Its action involves flexion, medial rotation, and adduction of the humerus.
The latter is a thin muscle located beneath the pectoralis major. Its action involves
lowering the scapula and raising the ribs.;
Alternative definition : CDISC: A group of muscles on the exterior of the thorax, in general extending from
the sternum to the humerus; primary function is movement of the upper forelimb.;