The deep dorsal sacrococcygeal ligament (ligamentum sacrococcygeum posterius profundum) is a continuation of the posterior longitudinal ligament.

[1] A flat band arising inside the sacral canal, posteriorly at the orifice of the fifth sacral segment, it descends to the dorsal surface of the coccyx under its longer fellow described below.

[3] The superficial dorsal sacrococcygeal ligament (ligamentum sacrococcygeum posterius superficiale) originates on the free margin of the sacral hiatus to attach on the dorsal surface of the coccyx.

It closes the posterior aspect of the most distal part of the sacral canal and corresponds to the ligamenta flava.

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