The coccyx consists of how many fused vertebrae?

• A. 4 fused vertebrae
• B. 3 fused vertebrae
• C. 5 fused vertebrae
• D. 2 fused vertebrae

Answer: (A)

The coccyx is the tailbone at the end of the spine, and it usually forms from the last coccygeal vertebrae that fuse together in adulthood. The typical configuration is four coccygeal vertebrae that fuse into a single bone. That makes four fused vertebrae the correct answer. Some people can have anatomical variants with three or five coccygeal vertebrae, or incomplete fusion, but four fused vertebrae is the most common and best matches what the question is asking. A smaller number, like two, would not account for the usual structure of the coccyx, and three or five represent less typical variations rather than the standard arrangement.