Anterior sacral foramina

At the ends of the transverse ridges of the pelvic surface of the sacrum are seen the anterior sacral foramina (or pelvic sacral foramina), four in number on either side, somewhat rounded in form, diminishing in size from above downward, and directed lateralward and forward.

They give exit to the anterior divisions of the sacral nerves and entrance to the lateral sacral arteries.