Which action is performed by the teres major muscle?

• A. Flexes and extends shoulder
• B. Rotates shoulder laterally
• C. Adducts and rotates shoulder medially
• D. Flexes shoulder and rotates shoulder medially

Answer: (D)

The teres major muscle is primarily responsible for adducting and medially rotating the shoulder joint. While some sources might describe its function as also assisting in shoulder flexion, its predominant actions emphasize adduction and medial rotation over flexion alone.

The correct choice reflects the combination of actions that the teres major performs: it effectively adducts the arm toward the body and rotates it medially. This function is vital for movements that require bringing the arm closer to the center line of the body, as well as when lifting or maneuvering the arm in various activities, which is often seen in overhead motions and pulling movements.

Understanding the role of the teres major is essential for grasping the dynamics of shoulder movement and how different muscles contribute to the range of motion and stability in the shoulder girdle.