Paul, you may be interested in what the Laser Spine Institute has to say (shown below).
It's a little different than the other websites which are determined to keep the TOE from suffering any embarrassment.
Of special interest, you may note that the
Sphincter ani externus is dependent on this "vestigial" body part.
In other words, without it, you wouldn't be able to control your bowels.
Enjoy this:
The tailbone, more properly known as the coccyx, is situated at the very end of the spinal column. The tailbone is made up of three to five fused vertebral bones, though four is most common. The tailbone derived its name because some people believe it is a leftover part from human evolution, though the notion that the tailbone serves no purpose is wrong. The coccyx is an extremely important source of attachment for tendons, ligaments and muscles, though it is structured quite differently than other parts of the spine.
The tailbone, or
coccyx, is the last of five regions of the spine below the cervical spine (neck), thoracic spine (middle back), lumbar spine (lower back) and sacrum (lower back). The tailbone connects to the sacrum via a cartilaginous joint called the sacrococcygeal symphysis. Interestingly, this joint is similar in composition to the spines intervertebral discs.
Muscles that attach to the tailbone and contribute to sitting, standing and bowel control include:
- Gluteus maximus large gluteal muscle; helps keep body erect
- Levator ani thin muscle; helps support organs of the pelvis
- Sphincter ani externus flat muscle; assists in bowel function
- Coccygeus triangular muscle; supports the pelvic floor
The tailbone is referred to as the coccygeal region and the bones diminish in size as they go down. Unlike the vertebral bones in most other spinal regions, the tailbone has no spinous processes, pedicles or laminae. Any pain that is felt in the coccyx is referred to as coccydynia. Sometimes, pain that is felt in the region of the tailbone is due to damage or injury in other parts of the spine. For instance, radicular, or radiating pain, that is felt shooting down the legs could be from foraminal stenosis in the lumbar spine, a condition that involves the narrowing of the foramen, or open spaces between the vertebrae through which nerve roots travel. If these spaces become narrow, increased stress is put on the nerves, which could contribute to symptoms of traveling pain, numbness and tingling. Other consequences could include a loss of ability to move properly. Needless to say, because the tailbone does support so much weight, injuries in this area transfer large amounts of increased stress to other areas of the spine, thereby making them more prone to damage