Broken upper arm bone. Coloured X-ray of the shoulder and arm of an adult man, showing a complete fracture (upper centre) of the head of the upper arm bone (humerus). This type of injury may require the bone to be pinned in place to heal. The head of the humerus articulates with the scapula (shoulder blade, upper left), forming a ball-and-socket shoulder joint. Above the scapula lies the clavicle (collar bone) that articulates with the scapula. The ribs of the chest are at lower left.