Shoulder. Coloured X-ray of the bones in the human shoulder. Three bones meet at the shoulder joint. The largest is the humerus or upper arm bone (at left). At its top is a ball (at upper left) that fits into a socket in the scapula (shoulder blade), seen here at upper right. Above the scapula (at top) is the clavicle (collar bone). The shoulder is an example of a ball and socket joint, which allows movement in any direction.