collarbone A horizontal bone above the first rib that makes up the front part of the shoulder. Also known as the clavicle, the collarbone links the breastbone (sternum) with the scapula, a triangular bone in the back of the shoulder. One end of the collarbone connects to the sternum, forming one side of the sternoclavicular joint. The other end of the collarbone connects to the scapula, there forming one side of the acromioclavicular joint.
