How does the shoulder work, and what does the rotator cuff do?
The shoulder is a joint with three main bones: the upper arm bone (humerus), the collarbone (clavicle), and the shoulder blade (scapula). The bones are held together by muscles, tendons, and ligaments. The rotator cuff keeps the upper arm bone in the shoulder socket and lets you raise and twist your arm. The shoulder is a ball-and-socket joint. The ball at the top of the upper arm bone fits into the socket of the shoulder blade. This socket is shallow, which lets you move your arm in a wide range of motion. But it also means that the muscles and tendons of the rotator cuff have to work hard to hold the bones in place. As a result, they are easy to injure and are prone to wear and tear. What causes rotator cuff disorders? Most rotator cuff disorders are caused by a combination of: • Normal wear and tear. Using your shoulder for many years slowly damages the rotator cuff. As you age, everyday activities can lead to changes in the rotator cuff, such as thinning and fraying of the tendons
