The anterior sacrococcygeal ligament or ventral sacrococcygeal ligament consists of a few irregular fibers, which descend from the anterior surface of the sacrum to the front of the coccyx, blending with the periosteum.1
Ebrall, Phillip S.; Sportelli, Louis; Donato, Phillip R. (2004). "Ligaments about the sacral apex", Assessment of the Spine. Elsevier Health Sciences. ISBN 0443072280.