Which set of muscles contributes to internal rotation of the shoulder?

Which set of muscles contributes to internal rotation of the shoulder?

• A. Subscapularis and pectoralis major.
• B. Pectoralis major, latissimus dorsi, and teres major.
• C. Subscapularis, pectoralis major, latissimus dorsi, teres major, and anterior deltoid.
• D. Subscapularis, pectoralis major, and teres minor.

Answer: (C)

Internal rotation of the shoulder is produced by muscles that pull the humerus toward the midline. The main contributors are subscapularis, pectoralis major, latissimus dorsi, and teres major. Subscapularis sits on the anterior aspect of the scapula and is the primary internal rotator, also helping stabilize the joint. Pectoralis major, attaching to the humerus, acts as a strong internal rotator, especially when the arm is flexed or adducted. Latissimus dorsi and teres major pull the humerus inward and also assist with adduction and extension. The anterior deltoid can contribute to internal rotation in certain arm positions due to its line of pull, providing an additional aiding role. Other options either miss one of these key internal rotators or include a muscle that primarily facilitates external rotation (such as teres minor). That combination makes the listed set the most complete and accurate for internal rotation.

Internal rotation of the shoulder is produced by muscles that pull the humerus toward the midline. The main contributors are subscapularis, pectoralis major, latissimus dorsi, and teres major. Subscapularis sits on the anterior aspect of the scapula and is the primary internal rotator, also helping stabilize the joint. Pectoralis major, attaching to the humerus, acts as a strong internal rotator, especially when the arm is flexed or adducted. Latissimus dorsi and teres major pull the humerus inward and also assist with adduction and extension. The anterior deltoid can contribute to internal rotation in certain arm positions due to its line of pull, providing an additional aiding role.

Other options either miss one of these key internal rotators or include a muscle that primarily facilitates external rotation (such as teres minor). That combination makes the listed set the most complete and accurate for internal rotation.