The Rotator Cuff consists of four muscles that function to dynamically stabilize the shoulder joint.
Rotator Cuff Biomechanics and Function
The rotator cuff functions to approximate the humerus in the glenoid fossa. The supraspinauts muscle assists the deltoid in abduction of the upper extremity while the subscapularis, infraspinatus, and teres minor function to depress the humeral head. The muscles of the rotator cuff dynamically stabilize the joint during movement. Additionally the rotator cuff muscles act as essential force couples to aide in normal strength and function. When the muscles work together they contribute to rotational movement about the shoulder joint while providing stability and support to the entire shoulder complex
The supraspinatus muscle is involved in the initial 15 to 30 degrees of abduction required for elevation of the upper extremity into overhead motions. The infraspinatus is responsible for external rotation of the shoulder in conjunction with the teres minor. The subscapularis muscle completes the rotator cuff as it functions as an internal rotator of the shoulder. The muscle most commonly involved in rotator cuff pathologies is the supraspinatus. The supraspinatus muscle in vulnerable to tearing due to its anatomic position and the biomechanics of the shoulder complex
