The hyoid bone is a U-shaped bone just under the mandible. The hyoid is closely associated with the skull but is not strictly a part of it. It anchors muscles, especially those of the tongue, and is the only bone in the body that is not linked to another. The blood vessels into and out of the hyoid bone are small branches of the external carotid artery, and are called superior thyroid arteries andmycontentbreak superior thyroid veins.