The coccyx (/ˈkɒksɪks/ kok-siks; plural: coccyges), commonly referred to as the tailbone, is the final segment of the vertebral column in humans and apes. Comprising three to five separate or fused coccygeal vertebrae below the sacrum. It is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between the sacrum and the coccyx.