veterinary anatomy term for hyoid bones, a modified portion of the ancestral branchial skeleton consisting of an articulated chain of bones extending from the mastoid region of the cranium on each side to the base of the tongue; in humans, it is reduced to a single bone, os hyoideum; in a typical mammal (the dog), it consists of a tympanohyoid cartilage attached to the cranium, followed by the stylohyoid, epihyoid, keratohyoid, basihyoid, and thyrohyoid bones. SYN: apparatus hyoideus.