 The rotator cuff is comprised of the subscapularis, biceps, supraspinatus, infraspinatus, and teres minor muscles. The subscapularis muscle may be divided into nine bellies. The muscle acts as the main internal rotator of the shoulder joint and provides support against traumatic posterior dislocation. The supraspinatus is the main abductor of the arm until 30 degrees after which the deltoid muscle takes over. It constitutes the posterior margin of the rotator cuff interval. A fusion between the infraspinatus and teres minor tendons is so common that the latter is sometimes considered the inferior belly of the infraspinatus. Hence, the presence of a separate teres minor tendon should be considered a variation. The infraspinatus acts in oppositions of the subscapularis as the main external rotator of the arm and works in conjunction with teres minor in completing this objective. Teres minor also assists with extension of the arm1,10. 