Which muscles are involved in shoulder extension?

Which muscles are involved in shoulder extension?

• A. Posterior Deltoid, Latissimus Dorsi, and Teres Major
• B. Anterior Deltoid and Pectoralis Major
• C. Biceps Brachii and Brachialis
• D. Latissimus Dorsi alone

Answer: (A)

Shoulder extension is moving the arm backward at the shoulder joint. The muscles that most effectively produce this action are the posterior part of the deltoid, the latissimus dorsi, and the teres major. The posterior deltoid pulls the humerus backward when the arm is in front of the body or raised. Latissimus dorsi, spanning from the lower back and hip to the humerus, powers pulling the arm downward and backward, extending the shoulder and aiding inward rotation and adduction. Teres major, attaching near the inferior angle of the scapula to the humerus, adds extension and adduction as well. Together, these three provide strong, coordinated shoulder extension across different positions. The other options don’t fit as well because the anterior deltoid and pectoralis major mainly flex the shoulder, moving the arm forward. The biceps brachii and brachialis focus on elbow flexion, with only a limited, non-primary role in shoulder movement.

Shoulder extension is moving the arm backward at the shoulder joint. The muscles that most effectively produce this action are the posterior part of the deltoid, the latissimus dorsi, and the teres major. The posterior deltoid pulls the humerus backward when the arm is in front of the body or raised. Latissimus dorsi, spanning from the lower back and hip to the humerus, powers pulling the arm downward and backward, extending the shoulder and aiding inward rotation and adduction. Teres major, attaching near the inferior angle of the scapula to the humerus, adds extension and adduction as well. Together, these three provide strong, coordinated shoulder extension across different positions.

The other options don’t fit as well because the anterior deltoid and pectoralis major mainly flex the shoulder, moving the arm forward. The biceps brachii and brachialis focus on elbow flexion, with only a limited, non-primary role in shoulder movement.