The only bone in the human body not attached to another bone is the hyoid bone.
The hyoid is a small, U-shaped bone in the front of the neck, positioned between the lower jaw and the thyroid cartilage. Unlike bones in the skeleton’s joints, it does not form a direct bony articulation with another bone. Instead, muscles and ligaments suspend it in place, linking it functionally to the skull, tongue, larynx, and surrounding structures.
This unusual arrangement allows the hyoid to move during swallowing and speech. Muscles attached to it help raise or lower the tongue and larynx, while the hyoid also provides an anchor for muscles in the floor of the mouth. Its mobility is one reason it is important in the coordinated actions of eating, breathing, and speaking.
The hyoid is sometimes described as “floating,” but that does not mean it moves freely without support. It is firmly held by muscles and connective tissues. The sternum and clavicle are connected to other bones, and the patella is embedded in the quadriceps tendon and connected through the knee’s tendon-and-ligament system.
The name hyoid comes from a Greek word meaning “shaped like the letter upsilon.”