Answer
The main function of the muscles that move the pectoral girdle is to stabilize the scapula to aid movements of the humerus.
Work Step by Step
The humerus can be moved in many different ways: it can be flexed, extended, abducted, adducted, and rotated medially or laterally. This requires that many muscles operate at the shoulder joint to effect these complex movements, and combination of movements. Some of these muscles are the latissimus dorsi, pectoralis major, deltoid, subscapularis, supraspinatus and the coracobrachialis.
Some of these muscles stabilize the scapula to facilitate movements of the humerus by others..
