The teres major muscle is located in the posterior aspect of the upper arm, forming part of the scapulohumeral (shoulder) muscles. It is a relatively small muscle compared to some of the surrounding muscles in the region.
Originating from the inferior angle of the scapula, the teres major takes its starting point from the bony prominence on the posterior aspect of the shoulder blade.
The muscle inserts into the intertubercular groove of the humerus, specifically at the crest of the lesser tubercle. This insertion site establishes a connection with the upper part of the arm bone.
Functionally, the teres major is a powerful medial rotator and adductor of the arm at the shoulder joint. It plays a key role in turning the humerus inward and drawing the arm toward the midline of the body. Additionally, the muscle assists in extending and stabilizing the shoulder joint, contributing to movements such as pulling the arm backward. The teres major works synergistically with other muscles of the shoulder girdle, providing strength and coordination in various upper limb movements.