Which muscle is NOT considered part of the rotator cuff?

The deltoid muscle is not considered part of the rotator cuff. The rotator cuff is made up of four specific muscles: supraspinatus, infraspinatus, subscapularis, and teres minor. These muscles work together to stabilize the shoulder joint and allow for a range of motion.

The deltoid, while a key muscle in shoulder movement, primarily functions to abduct the arm and contributes to the shoulder's overall strength and mobility. It sits on the outer shoulder and is distinct in its anatomical role compared to the rotator cuff muscles, which lie deeper and are involved primarily in shoulder stabilization during movements.

Understanding this distinction is crucial for recognizing the functional anatomy of the shoulder and diagnosing related injuries or conditions.