Rotator cuff stability vary according to their stiffness and the direction of the force they apply upon the joint. In addition to stabilizing the glenohumeral joint and controlling humeral head translation, the rotator cuff muscles also perform multiple functions, including abduction, internal rotation, and external rotation of the shoulder. The infraspinatus and subscapularis have significant roles in scapular plane shoulder abduction (scaption), generating forces that are two to three times greater than the force produced by the supraspinatus muscle. However, the supraspinatus is more effective for general shoulder abduction because of its moment arm. The anterior portion of the supraspinatus tendon is
Rotator cuff tear cuff is made up of the supraspinatus, infraspinatus, teres minor, and subscapularis. The supraspinatus is the most commonly affected. Treatment may include pain medication such as NSAIDs and specific exercises. It is recommended that people who are unable to raise their arm above 90 degrees after 2 weeks should be further assessed. In severe cases surgery may be indicted. Rotator cuff tears are common. Those over the age of 40 are most often affected. The condition has been described since at least the early 1800s. Many rotator cuff tears have no symptoms. Both partial and full thickness tears have been