The caudal vertebrae are the lowermost bones in the human vertebrae and are generally formed by the fusion of three to five degenerated bone fragments.
The spine from top to bottom are the cervical, thoracic, lumbar, sacral and coccygeal vertebrae. The caudal vertebrae, also known as the coccyx, are generally formed by the fusion of 3 to 5 degenerated bone fragments, which are pointed at the bottom and broad at the top, resembling a triangular conical bone, connected to the sacral vertebrae with cartilage and ligaments above, and connected to the iliacs on both sides by the ligaments of the pelvis, the coccygeal muscles, the levator ani muscles and other tissues.
As there are more ligaments and muscles attached near the coccyx, after long-term friction and other factors, the patient’s buttocks are prone to localized inflammation, causing buttock pain and other discomforts. In addition, the skin on the back side of the coccyx is weak, which may lead to coccyx fracture in case of trauma such as squatting. Since women’s pelvic cavity is wider and flatter than men’s, the tailbone is relatively easy to be injured when sitting down.