Pain in the region of the coccyx is referred to as coccygodynia. Despite being recognised for many centuries, coccydynia remains an unsolved mystery because of the perceived uncertainty in identifying the origin of the pain.
The coccyx is a triangular bone consisting of three to five segments: the first and largest of these vertebral segments articulates with the sacrum. The last three segments diminish in size and usually form a single piece of bone. The disc spaces in this region are extremely variable. Intact discs, discs with extensive clefts, discs with cystic or fibrocystic changes and discs replaced by synovial joints have all been reported.