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

The muscle that is not part of the rotator cuff is Teres major. The rotator cuff is a group of four muscles that stabilize the shoulder joint and facilitate a wide range of shoulder movements. These four muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Each of these muscles has specific functions related to shoulder mobility and stability.

Teres major, while located nearby and involved with arm movements, is not included in the rotator cuff group. It plays a role in arm adduction and medial rotation but does not contribute to shoulder stabilization in the same way the rotator cuff muscles do. Therefore, recognizing the distinction between these muscle groups is key in understanding shoulder anatomy and function.