Human Anatomy, Part 1 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2002

Special Section
Arthrology, artrologia [the study of bone joints] — Classification of joints and their general characteristics
Sacrococcygeal joint

Due to the fact that the coccyx consists of rudimentary vertebrae, the sacrococcygeal joint, junctura sacrococcygeal, has certain specific features. Between the bodies of the fifth sacral and the first coccygeal vertebrae lies an intervertebral disc, just like in true vertebral joints, with the sole difference that inside it, instead of a Nucleus pulposus, There is a small cavity. Running along the anterior surface of the coccyx is the ventral sacrococcygeal ligament, lig. sacrococcygeum ventrale, which is a continuation of the anterior longitudinal ligament. Along the posterior surface of the bodies of the sacral vertebrae and the coccyx runs the deep dorsal sacrococcygeal ligament, lig. sacrococcygeum dorsale profundum, analogous to the anterior longitudinal ligament. The inferior sacral hiatus is closed by the superficial sacrococcygeal ligament, lig. sacrococcygeum dorsale superficiale, which extends from the median sacral crest and the margins of the sacral hiatus downwards onto the posterior surface of the coccyx. It corresponds to the supraspinous and ligamenta flava. The lateral sacrococcygeal ligament, lig. sacrococcygeum laterale, is a homologue of the intertransverse ligament and runs along the lateral surfaces of the sacrum and coccyx.