Broken upper arm bone. Coloured X-ray of the right shoulder of a patient, showing a fracture (centre left) 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 humeral head articulates with the scapula (shoulder blade, upper right), forming the ball-and-socket shoulder joint (upper centre). Above the scapula, lies the clavicle (collar bone) that articulates with the scapula. The ribs of the chest are at lower right.