Coccyx · What Is It, Function, Injuries, and More

The coccyx is located in the terminal part of the vertebral column, or spinal column, which consists of 33 vertebrae organized into five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal. In some individuals, there can be one more or one less coccygeal vertebra with the resulting coccyx being the fusion of five or three vertebrae, respectively.  

The coccyx consists of a base, apex, anterior surface, posterior surface, and two lateral surfaces. The base is located superiorly and attaches to the apex of the sacrum, forming the sacrococcygeal joint. The apex is a rounded prominence that forms the endpoint of the vertebral column and serves as a site of attachment for muscles and ligaments of the pelvic floor. The anterior surface is smooth and slightly concave, whereas the posterior surface is convex. The coccygeal cornua are two large articular processes that project upwards from the base of the coccyx to articulate with the sacrum. Finally, the lateral surfaces of the coccyx are marked by two small transverse processes similar to those of the rest of the vertebrae.  

The coccyx can become injured due to several mechanisms. The most common injury is a fall onto the buttocks, which may occur when someone falls backwards or from a chair. Direct trauma to the tailbone can result in a bruised, dislocated, or broken coccyx. This condition is often managed conservatively with pain medications and rest while the bone heals.  

Another common condition is pain in the region of the coccyx called coccydynia. The most common cause of coccydynia is trauma to the coccyx, either due to a backwards fall or prolonged sitting on a hard or uncomfortable surface. In addition, the location of the coccyx makes it particularly susceptible to injury during childbirth, especially with prolonged or instrumented vaginal births. Non-traumatic coccydynia can result from a number of causes, including degenerative disc disease; hypermobility or hypomobility of the sacrococcygeal joint; infectious causes (e.g., pilonidal cyst); sacrococcygeal tumors; or psychological disorders, like somatization disorder.  

Individuals with coccydynia typically experience pain over the coccyx, commonly described as tailbone pain. The pain generally worsens with prolonged sitting, leaning back while seated, prolonged standing, and when arising from a seated position. Pain may also get worse with sexual intercourse or defecation. Fortunately, many cases of coccydynia resolve without any treatment or with simple supportive measures. Common measures include adopting a proper sitting position; using modified wedge-shaped cushions to relieve pressure from the coccyx when sitting; applying hot or cold compresses to the area; and medications, like acetaminophen or NSAIDs, to help relieve the pain. In cases of chronic coccydynia, treatment may include physical therapy; pelvic floor rehabilitation; osteopathic manipulative treatment; and interventional procedures, such as injections of local anesthetic around the coccyx area. If all other treatments fail, coccygectomy, or surgical removal of the coccyx, may be indicated.