Which muscle inserts at the greater tubercle of the humerus and has actions including flexion, adduction, and medial rotation at the shoulder?

Which muscle inserts at the greater tubercle of the humerus and has actions including flexion, adduction, and medial rotation at the shoulder?

• A. Latissimus Dorsi
• B. Infraspinatus
• C. Pectoralis Major
• D. Trapezius

Answer: (C)

The key idea is how a muscle’s insertion site on the humerus relates to the shoulder movements it can produce. Muscles that insert on the greater tubercle (like supraspinatus, infraspinatus, and teres minor) mainly contribute to rotation or abduction, not the combination of flexion, adduction, and medial rotation. The actions described align with the pectoralis major, which can flex the shoulder (especially the clavicular part), adduct the arm, and medially rotate the shoulder. However, pectoralis major does not insert on the greater tubercle; it attaches to the intertubercular groove (bicipital groove) of the humerus. That mismatch means the prompt combines an insertion site with actions that belong to a different insertion pattern. In short, the described actions point to pectoralis major, but the stated insertion site is incorrect for that muscle, and none of the listed choices perfectly matches both criteria.

The key idea is how a muscle’s insertion site on the humerus relates to the shoulder movements it can produce. Muscles that insert on the greater tubercle (like supraspinatus, infraspinatus, and teres minor) mainly contribute to rotation or abduction, not the combination of flexion, adduction, and medial rotation.

The actions described align with the pectoralis major, which can flex the shoulder (especially the clavicular part), adduct the arm, and medially rotate the shoulder. However, pectoralis major does not insert on the greater tubercle; it attaches to the intertubercular groove (bicipital groove) of the humerus. That mismatch means the prompt combines an insertion site with actions that belong to a different insertion pattern.

In short, the described actions point to pectoralis major, but the stated insertion site is incorrect for that muscle, and none of the listed choices perfectly matches both criteria.