Conditions & Treatments - Rotator Cuff Tendonitis (Supraspinatus Tendonitis)

The rotator cuff is comprised of a group of four muscles in the shoulder: supraspinatus, infraspinatus, subscapularis and teres minor. These muscles help hold the head of the humerus (ball) inside the shoulder socket by providing strength and stability. This muscle group also assists in moving the arm inward (internal rotation), outward (external rotation) and to the side (abduction). The image displays the rotator cuff muscles. The most commonly injured muscle in this group is the supraspinatus. Pain is usually located at the anterior aspect of the shoulder and can increase by bringing the arm outwards or sideways. These movements of the arm are usually weaker as well. The injury is caused because the tendon of the supraspinatus (a tendon connects muscle to bone) is injured and inflamed because of overuse of the shoulder, sudden movement of the shoulder, improper mechanics or a fall onto the shoulder. (image work of the United States Federal Government)