The coccyx, commonly known as the tailbone, is a small, triangular bone located at the very end of the vertebral column in humans and tailless primates. It's formed by the fusion of typically four (but sometimes three or five) coccygeal vertebrae.
Structure and Location
- The coccyx sits inferior to the sacrum, which is the large, triangular bone at the base of the spine.
- It is the final segment of the vertebral column.
- It's composed of fused vertebrae, meaning they are joined together into a single bony structure.
- The size and shape of the coccyx can vary between individuals.
Function
While often referred to as a vestigial structure (a remnant from a time when humans had tails), the coccyx still serves several important functions:
- Attachment point for muscles and ligaments: Several muscles of the pelvic floor and ligaments attach to the coccyx, providing stability and support to the pelvic region.
- Support during sitting: When sitting, the coccyx helps to bear weight, contributing to stability and balance. This function is most important when leaning back while seated.
- Potential source of pain: Despite its size, the coccyx can be a source of pain (coccydynia) due to injury (such as falls), childbirth, or repetitive strain.
Clinical Significance
- Coccydynia (Tailbone Pain): Pain in the coccyx can be caused by various factors, including falls, direct trauma, repetitive strain injuries (like cycling or rowing), childbirth, or, in some cases, no identifiable cause.
- Fractures: Although less common, the coccyx can be fractured due to significant trauma.
- Dislocation: The coccyx can be dislocated, particularly during childbirth.
Summary
The coccyx, or tailbone, is a small but significant bone at the end of the spine, providing crucial attachments for muscles and ligaments, contributing to stability and support during sitting, and, unfortunately, sometimes becoming a source of pain.
