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How do rotator cuff muscles help stabilize the shoulder joint?

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The human hip and pelvis — ball-and-socket joint Anterior view of the hip and pelvis, showing attachment of ligaments to the femur, ilium, ischium, and pubis.

The rotator cuff is composed of four muscles: the supraspinatus, infraspinatus, teres minor, and subscapularis, along with their tendons. These muscles form a supportive sleeve around the shoulder joint, which is a ball-and-socket joint. This arrangement helps to keep the head of the humerus (the upper arm bone) securely within the shoulder socket, thereby stabilizing the shoulder joint while allowing for a wide range of motion. The supraspinatus and deltoid muscles are the primary muscles responsible for lifting the arm away from the body (abduction).123