Which of the following is NOT part of the rotator cuff muscles?

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

Answer: (C)

The rotator cuff is a group of four muscles that stabilize the shoulder by hugging the head of the humerus into the glenoid during movements. Among the options, supraspinatus, infraspinatus, and subscapularis are all classic members of this cuff, each contributing to stabilizing the joint and guiding motion. The one that is not part of the rotator cuff is teres major. Teres major lies with other shoulder adductors and internal rotators, and while it helps move the arm, it does not encircle the shoulder to stabilize the humeral head the way the true rotator cuff muscles do. It is structurally separate from the cuff, and its primary actions are internal rotation, adduction, and extension, not the stabilizing role of the cuff muscles.