The coccyx (os coccygis) is a small triangular bone. It is formed from three or four vertebrae fused together. It articulates proximally with the apex of the sacrum. Coccygeal vertebrae are remnants of the tail and rudimentary vertebrae, fused together to form a single triangular bone, the coccyx. The number of coccygeal vertebrae varies from 3 to 5. The coccyx has only rudimentary vertebral elements of vertebra but these include:
Coccygodynia is a pain in or around the region of the coccyx. It is 5 times more common in women than in men. The most common are direct falls resulting in direct injury of the coccyx region. The result is an injury or partial dislocation of the sacrococcygeal junction that causes abnormal movement of the coccyx. In the majority of cases, the pain occurs only in the sitting position.