American Academy of Orthopeadic Surgeons
| The shoulder is the most moveable joint in the body. However, due to the large range of motion this ball and socket joint is extremely susceptible to injury. Both the large freedom of movement and the associated injury susceptibility are directly related to the anatomy of the shoulder. The shoulder is composed of three bones: the clavicle (collar bone), the scapula (shoulder blade), and the humerus (upper arm). The shoulder joint is actually composed of two separate articulations which together underlie the movement of the shoulder: the acromioclavicular (scapula to clavicle) and the glenohumoral joint (humerus to scapula). These two joints are held together by ligaments, with several muscles assisting to hold the glenohumoral joint. Finally, there are two main bursas contained in the shoulder; these fluid-filled sacs help to lubricate the shoulder joint, especially to allow easy movement of muscle tendons over the joint capsule. A subscapular bursa and a subacromial bursa open into the joint cavity. A common misconception with a shoulder injury is that a dislocation and a separation are one in the same. However, these two types of injuries are very different and involve entirely different anatomy. A separated shoulder is when the acromialclaviclar (AC) joint is disrupted whereas a dislocated shoulder is when the head of the humerus is displaced from the glenoid socket of the scapula (1). | |
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American Academy of Orthopeadic Surgeons
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