The shoulder is not a simple joint. Properly described as a complex, the shoulder consists of a system of three interconnecting bones, ligaments and muscles. Due to its complexity, the shoulder enjoys seveal unique features:

• The range of motion (ROM) of the shoulder is the greatest of all the joints in the body.
• The shoulder joint is very shallow, and therefore not very stable.
• Ligaments hold every other joint in the body, but the shoulder is held together by the capsule and by the small rotator cuff muscles.

Because of the intricacy, the shoulder complex carries the risk of unique injury. Many people develop complaints of the shoulder. The problems have a suprising variety. Otherwise healthy people and people who are already in hospitals both may feel the rath of an injured shoulder.

Despite the various populations of patients and the variety of injuries that may occur, shoulder problems can be grouped into several general categories. For patients who have been receiving some prior treatment, shoulder complaints often arise from overuse. For these patients injuries might occur secondary to wheelchair use, or to compensation for a functional loss (amputation, stroke). Many patient's who have already suffered one injury are prone to a second. For patients with no prior problems, injuries may include:

It is impossible to discuss damage to the shoulder without using the names of bones, muscles and nerves. It is very difficult to describe the function and location of the anatomy without using some technical language. The following pages lay out basic anatomy and its common terms before progressing to the discussion of diseases and their treatments.