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# Iliococcygeus

The iliococcygeus is the thin, flat back part of the levator ani in the pelvic floor; it forms a shelf that supports the pelvic organs.

Official name: Iliococcygeus muscle

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## What it is

The thin back part of the levator ani, from a tendinous arch on the pelvic side wall to the coccyx.

## What it does

Forms the flat back of the pelvic floor that supports the organs.

## Key points

- With the back fibres of the pubococcygeus it forms the levator plate, a near-horizontal shelf behind the anorectum on which the rectum, upper [vagina](https://durgical.com/en/anatomy/vagina/) and uterus rest when standing
- Thinnest part of the [levator ani](https://durgical.com/en/anatomy/levator-ani/); it arises from fascia (the back part of the tendinous arch of levator ani) rather than from bone, plus the ischial [spine](https://durgical.com/en/anatomy/region/spine/)
- Fibres from both sides meet in the midline anococcygeal raphe between the anus and the [coccyx](https://durgical.com/en/anatomy/coccyx/)

## Key facts

**Origin**
Tendinous arch of levator ani (obturator fascia) and ischial spine

**Insertion**
Anococcygeal body and coccyx

**Action**
Forms the posterior pelvic floor plate; supports the viscera

**Nerve**
Nerve to levator ani (S3–S4) and [pudendal nerve](https://durgical.com/en/anatomy/pudendal-nerve/) (S2–S4) branches

**Blood supply**
Inferior gluteal, internal pudendal and inferior vesical/vaginal arteries

## Relations

**In front**
[Pubococcygeus](https://durgical.com/en/anatomy/pubococcygeus-muscle/), with which it often blends without a clear boundary

**Behind**
[Coccygeus](https://durgical.com/en/anatomy/coccygeus-muscle/), which continues the floor back to the [sacrum](https://durgical.com/en/anatomy/sacrum/)

**Lateral**
[Tendinous arch of levator ani](https://durgical.com/en/anatomy/tendinous-arch-of-levator-ani/) on the [obturator internus](https://durgical.com/en/anatomy/obturator-internus/); below the arch the obturator internus forms the outer wall of the ischioanal fossa

**Above**
Pelvic fascia, then the [rectum](https://durgical.com/en/anatomy/rectum/) and the pelvic organs that rest on the levator plate

**Below**
Fat of the ischioanal fossa, with the pudendal canal on its lateral wall

## How to find it

It cannot be felt from outside. On vaginal or rectal examination it is a thin sheet on the posterolateral wall, higher and less distinct than the [puborectalis](https://durgical.com/en/anatomy/puborectalis/) sling. In surgery it is seen from above when the [peritoneum](https://durgical.com/en/anatomy/peritoneum/) and pelvic fascia are lifted off the side wall.

## On imaging

On sagittal and coronal MRI the levator plate normally lies close to horizontal; in pelvic organ prolapse and with ageing it tilts downwards and the floor sags into a deeper bowl, widening the hiatus in front of it.

## Common problems

- Stretching or tearing in vaginal birth.
- Pelvic organ prolapse.
- Urinary or faecal incontinence.
- Overactive, painful pelvic floor (pain with sex, pelvic pain).

## How it is diagnosed

Pelvic examination, sometimes ultrasound or MRI of the pelvic floor.

## Treatment

- Pelvic floor muscle training (Kegel exercises) with a physiotherapist.
- A pessary (a removable support placed in the vagina).
- Surgery for prolapse that bothers the person.

## Clinical notes

- Iliococcygeus fascia fixation sutures the vaginal vault to the fascia over this muscle just below and in front of the ischial spine, an alternative to sacrospinous fixation for vault prolapse
- A downward-tilted levator plate is associated with uterine and vault prolapse, because the organs lose the shelf that holds them over the floor

## Anatomical variants

- A gap can exist between the muscle and its tendinous arch (hiatus of Schwalbe), a rare site of pelvic floor hernia
- MRI may show it thin or partly absent in some women; with ageing the genital hiatus widens

## Related conditions

- [Pelvic organ prolapse](https://durgical.com/en/conditions/pelvic-organ-prolapse/)
- [Anorectal abscess and fistula](https://durgical.com/en/conditions/anorectal-abscess-and-fistula/)
- [Rectal prolapse](https://durgical.com/en/conditions/rectal-prolapse/)

## Test yourself

Think of the answer, then tap the question to see it.

## What shelf does the iliococcygeus form with the back fibres of the pubococcygeus, and what rests on it?

The levator plate, a near-horizontal shelf on which the rectum, upper vagina and uterus rest when standing.

## From where does the iliococcygeus arise?

From fascia, the back part of the tendinous arch of levator ani, and from the ischial spine; it is the thinnest part of the levator ani.

## What is iliococcygeus fascia fixation used for?

Vaginal vault prolapse: the vault is sutured to the fascia over the iliococcygeus just below and in front of the ischial spine.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
musculus iliococcygeus TA2 2404

**Official Spanish (DeCS)**
Músculo iliococcígeo DeCS D017773

**English (TA2)**
Iliococcygeus muscle

## Related

- [Pubococcygeus](https://durgical.com/en/anatomy/pubococcygeus-muscle/)
- [Coccygeus](https://durgical.com/en/anatomy/coccygeus-muscle/)
- [Tendinous arch of levator ani](https://durgical.com/en/anatomy/tendinous-arch-of-levator-ani/)

Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=31203&filter=ths_termall&q=Diafragma%20P%C3%A9lvico); [Anatomy, Abdomen and Pelvis: Levator Ani Muscle](https://www.ncbi.nlm.nih.gov/books/NBK556078/); [Anatomy, Abdomen and Pelvis: Pelvic Floor](https://www.ncbi.nlm.nih.gov/books/NBK482200/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/iliococcygeus-muscle/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/iliococcygeus-muscle/