What is the number of coccygeal vertebrae in an adult human?

In adults, the coccyx, commonly referred to as the tailbone, typically consists of one singular structure formed from the fusion of multiple coccygeal vertebrae. While infants are born with about four to five separate coccygeal vertebrae, these vertebrae gradually fuse together during development. By adulthood, this results in the coccyx being a single bone, which is often counted as one vertebra when referring to coccygeal vertebrae. This anatomical structure plays a role in supporting pelvic organs and providing attachment for ligaments and muscles. Understanding this aspect of human anatomy helps to clarify why the number of coccygeal vertebrae in an adult is considered to be one.