Origin: Sacrospinous ligament
Nerve: Sacral nerves: S4, S5 or S3-S4
Action: Closing in the back part of the outlet of the pelvis
The Coccygeus is situated behind the preceding. It is a triangular plane of muscular and tendinous fibers, arising by its apex from the spine of the ischium and sacrospinous ligament, and inserted by its base into the margin of the coccyx and into the side of the lowest piece of the sacrum. It assists the Levator ani and Piriformis in closing in the back part of the outlet of the pelvis.