Which bone is U-shaped and does not articulate with any other bone?

• A. Mandible
• B. Sphenoid
• C. Ethmoid
• D. Hyoid

Answer: (D)

The hyoid bone is the one that fits this description. It sits in the front of the neck between the jaw and the larynx and is held in place by ligaments and muscles rather than forming a joint with another bone. Because it doesn’t connect to any other bone, it remains free-floating. Its shape is U-shaped, with a body and horns, which is why it’s described as U-shaped. The hyoid also plays a role in supporting the tongue and aiding swallowing and speech. In contrast, the mandible forms a joint with the temporal bone at the jaw, and the sphenoid and ethmoid are skull bones that articulate with multiple other bones, so they don’t share this non-articulating characteristic.