The rotator cuff is a group of muscles and tendons that surround the shoulder joint and help to provide stability and allow for a wide range of motion. The rotator cuff muscles include the supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles and tendons attach the upper arm bone (humerus) to the shoulder blade (scapula) and help to raise, rotate, and lower the arm. The rotator cuff is essential for many everyday activities, such as reaching, lifting, and throwing. A rotator cuff injury can cause pain and difficulty with shoulder movement. Treatment for a rotator cuff injury may include rest, physical therapy, and in some cases, surgery.