Clavicle, also called the collarbone, curved anterior bone of the shoulder (pectoral) girdle in vertebrates; it functions as a strut to support the shoulder. The clavicle is present in mammals with prehensile forelimbs and in bats, and it is absent in sea mammals and those adapted for running. In humans the two clavicles, on either side of the anterior base of the neck, are horizontal, S-curved rods that articulate laterally with the outer end of the shoulder blade (the acromion) to help form the shoulder joint; they articulate medially with the breastbone (sternum).

Source: Britannica