The shoulder is a joint suspended by many muscles surrounding the upper extremity. The shoulder bones include the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). The only connection of the shoulder girdle to the remainder of the skeleton is the clavicle. The scapula is an important part of the shoulder joint as it serves as an anchor for many muscles and contains the socket part of the shoulder (glenoid). The upper end of the humerus has a ball-like shape that articulates with the socket, and the humerus also serves as an attachment point for many muscles and tendons. One of the most important is the rotator cuff. Disruption of any of these parts can create difficulty with the function of the shoulder.
Fracture type about the shoulder varies by age. The majority of fractures in children occur in the clavicle. In the adult, fractures within the upper part of the arm (proximal humerus) occur with increasing frequency with older age. Some fractures may occur with dislocation of the shoulder joint.