What are the prime movers for shoulder flexion?

What are the prime movers for shoulder flexion?

• A. Anterior deltoid & Coracobrachialis
• B. Latissimus dorsi & Teres major
• C. Posterior deltoid & Infraspinatus
• D. Pectoralis major & Subscapularis

Answer: (A)

Shoulder flexion is driven mainly by the anterior deltoid and the coracobrachialis. The anterior deltoid, which crosses the shoulder from the clavicle and acromion to the humerus, actively lifts the arm forward. The coracobrachialis originates from the coracoid process and assists by flexing the humerus toward the chest, acting as a synergist to the deltoid. Other muscles listed do not flex the shoulder: latissimus dorsi and teres major extend, adduct, and internally rotate; the posterior deltoid extends and horizontally abducts; infraspinatus and subscapularis rotate the shoulder and stabilize the joint. Pectoralis major can contribute to flexion in certain positions, but the primary movers in standard shoulder flexion testing are the anterior deltoid and coracobrachialis.

Shoulder flexion is driven mainly by the anterior deltoid and the coracobrachialis. The anterior deltoid, which crosses the shoulder from the clavicle and acromion to the humerus, actively lifts the arm forward. The coracobrachialis originates from the coracoid process and assists by flexing the humerus toward the chest, acting as a synergist to the deltoid. Other muscles listed do not flex the shoulder: latissimus dorsi and teres major extend, adduct, and internally rotate; the posterior deltoid extends and horizontally abducts; infraspinatus and subscapularis rotate the shoulder and stabilize the joint. Pectoralis major can contribute to flexion in certain positions, but the primary movers in standard shoulder flexion testing are the anterior deltoid and coracobrachialis.