Shoulder adduction relies on which muscle group?

• A. Latissimus dorsi, pectoralis major, teres minor.
• B. Latissimus dorsi, pectoralis major, teres major, and coracobrachialis.
• C. Pectoralis major and teres minor.
• D. Latissimus dorsi and coracobrachialis.

Answer: (B)

Shoulder adduction is moving the arm toward the body's midline, powered by muscles that cross the glenohumeral joint and can pull the humerus medially. The main players are latissimus dorsi and teres major, which pull the arm downward and inward. Pectoralis major also contributes to adduction, especially with the arm in certain positions, and helps rotate the arm toward the body. Coracobrachialis, while smaller, assists in adduction as the arm moves inward, particularly when the arm is flexed. Because these four muscles together can produce adduction, they form the best answer. Note that teres minor mainly helps with external rotation and does not serve as an adductor, which is why it isn’t part of the adduction group.