The coccyx is the lowest section of the spine below the sacrum. It consists of 4 to 5 small vertebrae, whose original joints have usually grown together to form a total bone structure. The coccyx serves mainly as an attachment point for tendons and ligaments of the pelvic floor and hip.
What is the coccyx?
Tailbone pain should be medically evaluated. Prolonged and ergonomically incorrect sitting could be the cause. The coccyx is the lowest part of the spine, immediately following the sacrum. It consists of 4 to 5 somewhat atrophied vertebrae, whose vertebral joints have usually been stiffened by the body itself through ossification and have usually grown together to form a total bone structure. It is very likely a phylogenetic regression (rudiment) of the tail, which was no longer of use due to the specific way of life of man and his ancestors. The regression is not complete because the coccyx performs an important function for the statics of the body as a counter-bearing for the force absorption of tendons, ligaments and muscles of the pelvic floor, pelvis and hips. Total regression of the coccyx would result in problems with strength and statics in the hips and pelvis. Evolutionary regression can occur when random genetic mutations alter certain body characteristics or physiological conversions. If the changes involve a favorable adaptation to new environmental or living conditions, they prevail population-genetically. In the opposite case, the gene mutation would not assert itself population-genetically and would gradually be lost again.
Anatomy and structure
A characteristic feature of the coccyx is the fusion of the 4 to 5 coccygeal vertebrae into a single bony body. This process is called synostosis. The intervertebral discs and intervertebral cartilage that were originally present lost their function and were replaced by bone tissue. Only at the uppermost coccygeal vertebra are the rudimentary structures of a vertebral body still recognizable, while the remaining – downward tapering – vertebrae have fused together to form a cone-shaped, bony structure. The end of the coccyx is formed by a small, button-like piece of bone. The uppermost coccygeal vertebra is connected to the sacrum above it, which also consists of 5 vertebrae fused together and is connected to the ilium of the pelvis by the rather fixed and not very mobile sacroiliac joint (sacroiliac joint). Thus, the sacrum forms part of the spine and the ilium at the same time.
Function and tasks
The main function of the coccyx is to absorb forces from the attached muscles, ligaments and tendons of the pelvic floor, pelvis and hips. It thus fulfills an important role in the statics of the body. The fusion into a coherent bone favors its suitability as a support for tendons and ligaments of the pelvic floor and hips. During the embryonic phase, the coccyx temporarily protrudes and is reenclosed by tissue during further development well before birth. Further regression of the coccyx during evolution would require a greatly altered solution for the attachment points of the ligaments and tendons, which currently make use of the coccyx.
Diseases and ailments
The exposed position of the coccyx makes it susceptible to injury from falls on the buttocks or from direct impact. It can result in sprains, contusions, or even a painful classic fracture or, less commonly, dislocation. The necessary immobilization of the coccyx to heal the fracture is practically impossible, so further pain cannot be prevented and can only be treated symptomatically. To relieve the pressure on the fracture site, a ring cushion can be used for sitting positions, which partially diverts the occurring pressure forces to the gluteal muscles. The less common dislocation, which is not always easy to diagnose, can be reset by an experienced physician or therapist using the thumb and middle finger. The middle finger is inserted into the rectum to push the coccyx back into the correct position, assisted by the thumb, which must simultaneously exert pressure on the coccyx from the outside. If the “dislocation” is successful, the pain is quickly relieved.Nonspecific pain in the coccyx can also disappear without treatment. However, if the pain is prolonged and becomes chronic, it is coccygodynia or coccygodynia with very different causes. A common cause of long-lasting coccyx pain is inflammation of the tendons, ligaments or muscles at the point of attachment to the coccyx, or microtrauma, which is promoted by overloading due to an unfavorable sitting posture or by unaccustomed constantly recurring movement patterns. They may require – usually protracted – therapy with anti-inflammatory and analgesic agents. Nerve irritation due to a herniated disc in the lower part of the lumbar spine can also be the cause of coccygodynia. In rare cases, the condition is caused by tumors.
