There are typically four pairs of dorsal sacral foramina.  These communicate with the sacral canal  via the intervertebral foramina.  The foramina transmit the dorsal rami of the first to fourth sacral spinal nerves, their coverings, lateral sacral arteries and venous plexuses.

Just medial to the foramina is a vertical row of four small tubercles, which constitute the intermediate sacral crest.