Which muscles assist shoulder flexion in addition to the primary movers?

• A. Coracobrachialis and Biceps Brachii
• B. Latissimus Dorsi
• C. Anterior Deltoid and Pectoralis Major
• D. Supraspinatus

Answer: (A)

When the shoulder moves into flexion, the main drivers are the anterior deltoid and the clavicular part of the pectoralis major. The muscles that can assist this motion beyond those primary movers are the coracobrachialis and the biceps brachii. Coracobrachialis reaches from the coracoid process to the humerus and helps lift the arm forward and slightly in toward the body, adding to flexion. The biceps brachii crosses the shoulder joint, and when the elbow is flexed and the forearm is supinated, it can pull the humerus upward and forward, contributing to shoulder flexion as well. Latissimus dorsi would pull the arm backward (extension and adduction), so it doesn’t assist flexion; supraspinatus mainly initiates and stabilizes abduction rather than flexion; and the described muscles are the ones that provide extra help beyond the primary movers.