sacral hiatus

There are up to three lateral sacrococcygeal ligaments on either side of the sacral hiatus.

The sacral canal ends in an opening known as the sacral hiatus.

It stretches from median sacral crest and the free margin of the sacral hiatus to the dorsal surface of the coccyx.

The coccygeal nerve, the last spinal nerve, emerges from the sacral hiatus, unites with the ventral rami of the two last sacral nerves, and forms the coccygeal plexus.

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.

The laminae of the fifth sacral vertebra, and sometimes those of the fourth, fail to meet behind, and thus a sacral hiatus occurs in the posterior wall of the sacral canal.