The sacrococcygeal symphysis (sacrococcygeal articulation, articulation of the sacrum and coccyx) is an amphiarthrodial joint, formed between the oval surface at the apex of the sacrum, and the base of the coccyx.

[2] Occasionally the coccyx is freely movable on the sacrum, most notably during pregnancy; in such cases a synovial membrane is present.

[2] The joint is palpable deep within the natal cleft, and can be felt as a horizontal groove.

With the palpating finger on the dorsal surface of the coccyx, a degree of rotation can be produced with an applied forward pressure.

[2] This article incorporates text in the public domain from page 309 of the 20th edition of Gray's Anatomy (1918)