Shoulder Bones and Joints
The glenohumeral joint (shoulder joint) is considered a ball and socket joint. The joint brings together the head of the humerus bone (the ball) and the glenoid fossa of the scapula (the socket.) The head of the humerus is large and the glenoid fossa is small. This gives the joint mobility, but causes it to be more unstable.
The acromioclavicular joint is formed by the meeting of the distal end of the clavicle (collar bone,) and the distal end of the acromion, a part of the scapula (shoulder blade.)
The sternoclavicular joint is formed but the juncture of the proximal end of the clavicle (collar bone) and the sternum.
The osseous joint surfaces all have articular cartilage, which covers the ends of the bones. The articular cartilage has a smooth and shiny surface that allows the ends of the bones in the joint to slide freely over each other.