Injuries to which rotator cuff muscle primarily affect abduction?

Injuries to which rotator cuff muscle primarily affect abduction?

• A. Infraspinatus
• B. Subscapularis
• C. Supraspinatus
• D. Teres minor

Answer: (C)

The correct choice is the supraspinatus muscle, which plays a crucial role in the abduction of the arm, particularly during the first 15 degrees of motion. This muscle is positioned on the superior aspect of the scapula and its primary function is to initiate the movement of the arm away from the body. When the supraspinatus is injured, the individual may experience difficulty with raising the arm or lifting it to the side, as the first stage of abduction is significantly hindered. This is essential because the deltoid muscle, which takes over to continue the process of abduction after the initial degrees, relies on the supraspinatus to initiate the movement efficiently. The other rotator cuff muscles have different primary functions. The infraspinatus and teres minor are primarily responsible for external rotation of the shoulder, while the subscapularis aids in internal rotation. Although these muscles support shoulder stability and contribute to overall arm movement, they do not primarily influence the initiation of abduction like the supraspinatus does. This distinction emphasizes the unique role of the supraspinatus in the mechanics of shoulder movement.

The correct choice is the supraspinatus muscle, which plays a crucial role in the abduction of the arm, particularly during the first 15 degrees of motion. This muscle is positioned on the superior aspect of the scapula and its primary function is to initiate the movement of the arm away from the body.

When the supraspinatus is injured, the individual may experience difficulty with raising the arm or lifting it to the side, as the first stage of abduction is significantly hindered. This is essential because the deltoid muscle, which takes over to continue the process of abduction after the initial degrees, relies on the supraspinatus to initiate the movement efficiently.

The other rotator cuff muscles have different primary functions. The infraspinatus and teres minor are primarily responsible for external rotation of the shoulder, while the subscapularis aids in internal rotation. Although these muscles support shoulder stability and contribute to overall arm movement, they do not primarily influence the initiation of abduction like the supraspinatus does. This distinction emphasizes the unique role of the supraspinatus in the mechanics of shoulder movement.