What are the primary actions of the teres major muscle?

The teres major muscle plays a crucial role in shoulder movement, primarily performing shoulder adduction, shoulder extension, and medial rotation. Located on the back side of the shoulder, the teres major originates from the inferior angle of the scapula and inserts into the humerus.

When the muscle contracts, it brings the arm closer to the body (adduction), moves the arm backward (extension), and rotates the arm towards the body (medial rotation). This combination of actions allows for significant mobility and stability during various activities, such as reaching behind, pulling, or performing certain lifting motions.

Understanding the function of teres major in relation to these primary actions is essential for comprehending shoulder mechanics and the coordination of muscle groups during various movements. The other options reflect different sets of actions that do not accurately characterize the teres major's role.