 The pec minor also works in conjunction with the rhomboid muscle and levator scapulae to perform downward rotation of the scapulae.Muscles which attach to the scapulae that adduct and extend the arm include the posterior deltoid muscles, the teres major, and minor stabilizing contribution from some rotator cuff muscles (infraspinatus and teres minor as lateral rotators, subscapularis as medial rotators).Muscles which flex the elbow joint such as the biceps brachii muscle, brachialis muscles and brachioradialis muscle are active to improve leverage.