CorpusHuman Anatomy
MuscularMuscle

Coccygeus

Musculus coccygeus

Also known as: ischiococcygeus

A small triangular muscle forming the posterior part of the pelvic diaphragm. It runs from the ischial spine to the side of the lower sacrum and coccyx.

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Overview

Coccygeus (ischiococcygeus) lies posterior to iliococcygeus, on the pelvic surface of the sacrospinous ligament, with which it is fused and of which it is the muscular remnant. Its fibres fan from the ischial spine to the lateral margins of the lower sacrum and coccyx. It completes the pelvic diaphragm posteriorly, supports the pelvic viscera and pulls the coccyx forward after it has been pushed back during defecation or childbirth. In tailed mammals, its homologue wags the tail.

Anatomy

Origin

Ischial spine (and sacrospinous ligament).

Insertion

Lateral margins of the inferior sacrum and the coccyx.

Action

Supports the pelvic floor; pulls the coccyx forward.

Innervation

Direct branches of the anterior rami of S4–S5.

Nerve roots

S4–S5

Arterial supply

Inferior gluteal and internal pudendal arteries.

Function

  • Completes the posterior pelvic diaphragm
  • Supports the pelvic viscera
  • Flexes the coccyx

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.