What most people call the shoulder is really several joints that combine with tendons and muscles to allow a wide range of motion in the arm — from scratching your back to throwing the perfect pitch.
Mobility has its price, however. It may lead to increasing problems with instability or impingement of the soft tissue or bony structures in your shoulder, resulting in pain. You may feel pain only when you move your shoulder or all of the time. The pain may be temporary or it may continue and require medical diagnosis and treatment.