Shoulder anatomy and function

The shoulder is the most mobile and flexible joint in the human body. We all depend upon our shoulders for a very important reason -- the shoulder joint is what allows us to control where we can move our arms in order to use them. Shoulder pain can be one of the most frustrating problems for patients because a shoulder that is not working normally interferes with almost every part of daily life. There is a very fine balance between mobility and stability in the shoulder that allows us to have freedom of movement throughout our entire lives, with a minimal amount of pain and problems. Although there are many reasons why this balance can be upset, the causes of the more common shoulder problems are easy to understand once you gain a little knowledge about how your shoulder works.

The shoulder can be considered a "ball and socket joint," but it is very different from the hip joint, which is also a ball and socket joint. The hip joint has more natural stability than a shoulder joint because the ball of the hip is almost entirely surrounded by the socket of the pelvis. In contrast, the shoulder is much more similar to a golf ball resting on a tee. In the shoulder, the position of the golf ball on the tee is controlled by a complicated arrangement of muscles, tendons, ligaments, and nerves. This arrangement is a delicate balancing act, and injuries to the shoulder can upset the balance, causing you to have a significant amount of pain and shoulder problems. In the following pages, we will discuss many aspects of shoulder anatomy including which bones, muscles, tendons, ligaments, and nerves make up the shoulder and how they function normally.

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