Which muscle medially rotates the shoulder?

Which muscle medially rotates the shoulder?

• A. Supraspinatus
• B. Biceps Brachii
• C. Subscapularis
• D. Flexor Carpi Radialis

Answer: (C)

Medial rotation of the shoulder is produced by muscles that pull the humerus inward toward the body. The primary muscle for this action is the subscapularis, a rotator cuff muscle. It originates on the subscapular fossa of the scapula and inserts onto the lesser tubercle of the humerus. When it contracts, it pulls the front of the humerus toward the chest, rotating the arm inward and helping stabilize the glenohumeral joint. Supraspinatus mainly initiates and assists with arm abduction and helps stabilize the head of the humerus, but it does not medially rotate. Biceps brachii can flex the shoulder and forearm supination, but it is not the primary internal rotator of the humerus. Flexor carpi radialis acts at the wrist, not the shoulder, so it has no role in shoulder rotation.

Medial rotation of the shoulder is produced by muscles that pull the humerus inward toward the body. The primary muscle for this action is the subscapularis, a rotator cuff muscle. It originates on the subscapular fossa of the scapula and inserts onto the lesser tubercle of the humerus. When it contracts, it pulls the front of the humerus toward the chest, rotating the arm inward and helping stabilize the glenohumeral joint.

Supraspinatus mainly initiates and assists with arm abduction and helps stabilize the head of the humerus, but it does not medially rotate. Biceps brachii can flex the shoulder and forearm supination, but it is not the primary internal rotator of the humerus. Flexor carpi radialis acts at the wrist, not the shoulder, so it has no role in shoulder rotation.