The teres major muscle is part of six muscles in the human body referred to as the scapulohumeral muscles. The muscle is located on the underside of the upper arm, in the area between the shoulder and elbow. It has a flat shape and is supplied with nerves from the lower subscapular nerve. The arteries supply blood and oxygen to the muscle. The muscle is located near the teres minor muscle, which is the primary muscle found surrounding the rotator cuff. The teres minor controls movement of the rotator cuff, but the teres major has no impact on the rotator cuff. It starts just below the underarm or armpit and stops at the top of the humerus. The teres major muscle is considered a medial rotator and helps control movement of the humerus. The muscle helps the latissimua dorsi in moving the humerus back and down, when extended. The humerus is the large bone of the upper arm. The teres muscle stabilizes the upper portion, or head, of the humerus.