Which bone is uniquely described as the only bone in the body not attached to another bone?

The hyoid bone is indeed uniquely described as the only bone in the body not directly attached to another bone. It serves as a critical component in the anatomy of the neck and plays an essential role in several functions, including supporting the tongue and aiding in speaking and swallowing. The hyoid bone is suspended in the neck by a collection of ligaments and muscular attachments rather than by bony connections, which distinguishes it from other bones in the skeletal system.

This unique characteristic of the hyoid bone allows it to function effectively as a support structure without being anchored to the skeletal framework of the body. Its placement and design give it a significant role in various physiological processes, such as phonation and the movement of the airways. While other bones like the mandible, maxilla, and temporal bone are critical in the structure of the jaw and skull, they are all articulated (connected) to other bones, which is not the case for the hyoid.