The teres major is a small, cylindrical muscle located in the upper back, specifically near the shoulder. It originates from the lower part of the scapula and attaches to the humerus, the bone of the upper arm. This muscle plays a key role in the movement of the shoulder, particularly in actions like internal rotation and adduction. Although it is often confused with the larger latissimus dorsi, the teres major assists in similar functions but is smaller in size. It is important for various activities, including lifting and pulling motions, contributing to overall shoulder stability and mobility.