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[Joints and ligaments](https://durgical.com/en/anatomy/system/joints-and-ligaments/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/)

# Sacrotuberous ligament

The sacrotuberous ligament is a long band from the [sacrum](https://durgical.com/en/anatomy/sacrum/) to the sitting bone (ischial tuberosity); it steadies the [pelvis](https://durgical.com/en/anatomy/region/pelvis/).

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## What it is

A long, strong band from the sacrum and coccyx to the ischial tuberosity (sitting bone).

## What it does

Keeps the lower sacrum from tipping and helps steady the pelvis. Part of the hamstring origin blends with it.

## Key points

- Forms the posterolateral border of the perineum, which runs from the [pubic symphysis](https://durgical.com/en/anatomy/pubic-symphysis/) along the ischiopubic rami and ischial tuberosities to the [coccyx](https://durgical.com/en/anatomy/coccyx/)
- The pudendal nerve can be trapped between it and the sacrospinous ligament (pudendal neuralgia)
- Pierced by the perforating cutaneous nerve (S2–S3), which supplies the [skin](https://durgical.com/en/anatomy/skin/) of the lower buttock

## Key facts

**Attaches**
Posterior iliac spines, lateral sacrum and coccyx to ischial tuberosity

**Function**
Resists nutation (upward tilt of lower sacrum); with sacrospinous turns sciatic notches into foramina

**Tight in**
Sacral nutation

## Relations

**Superficial**
[Gluteus maximus](https://durgical.com/en/anatomy/gluteus-maximus-muscle/), which partly arises from it

**Deep**
[Sacrospinous ligament](https://durgical.com/en/anatomy/sacrospinous-ligament/), with the [pudendal nerve](https://durgical.com/en/anatomy/pudendal-nerve/) and internal pudendal vessels crossing between the two near the ischial [spine](https://durgical.com/en/anatomy/region/spine/)

**Below**
Ischial tuberosity and the [long head of biceps femoris](https://durgical.com/en/anatomy/long-head-of-biceps-femoris/); its falciform process curves forward along the ischial ramus

## How to find it

Deep in the lower buttock: firm pressure between the ischial tuberosity and the side of the lower sacrum and coccyx meets a taut band through gluteus maximus.

## On imaging

Radiographs do not show it unless it calcifies, seen as a linear density from the sacrum to the ischial tuberosity. MRI shows it as a thick dark band blending with the hamstring origin at the tuberosity; this junction is checked in hamstring avulsions. In suspected pudendal entrapment, CT or ultrasound is used mainly to guide an injection between it and the sacrospinous ligament.

## Clinical notes

- Surgical decompression of pudendal nerve entrapment may divide this ligament
- Torn in unstable pelvic ring injuries (rotationally or vertically unstable)
- Lies close to the pudendal canal (Alcock canal), which runs along the side wall of the ischioanal fossa

## Anatomical variants

- Its lower fibres often run straight on into the [tendon of the long head of biceps](https://durgical.com/en/anatomy/tendon-of-the-long-head-of-biceps/) femoris; some texts regard the ligament as the cut-off upper end of that tendon

## Related conditions

- [Sacroiliac joint pain](https://durgical.com/en/conditions/sacroiliac-joint-pain/)

## Test yourself

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

## Where does the sacrotuberous ligament attach?

From the posterior iliac spines, lateral sacrum and coccyx to the ischial tuberosity.

## Between which two ligaments can the pudendal nerve be trapped, causing pudendal neuralgia?

Between the sacrotuberous and sacrospinous ligaments, near the ischial spine.

## What do the sacrotuberous and sacrospinous ligaments do to the sciatic notches?

They turn the greater and lesser sciatic notches into foramina; the sacrotuberous ligament also resists sacral nutation.

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

## Its names

**Official Latin (TA2)**
ligamentum sacrotuberale TA2 1850

**Official Spanish (DeCS)**
Ligamento sacrotuberoso

**English (TA2)**
Sacrotuberous ligament

**Also called**
sacrotuberal ligament · ligamentum sacrotuberosum

## Related

- [Sacrospinous ligament](https://durgical.com/en/anatomy/sacrospinous-ligament/)
- [Biceps femoris (long head)](https://durgical.com/en/anatomy/long-head-of-biceps-femoris/)
- [Sacrum](https://durgical.com/en/anatomy/sacrum/)
- [Hip bone](https://durgical.com/en/anatomy/hip-bone/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb: Pelvic Joints](https://www.ncbi.nlm.nih.gov/books/NBK538523/); [Anatomy, Abdomen and Pelvis: Ligaments](https://www.ncbi.nlm.nih.gov/books/NBK493215/); Anatomy of the Human Body (20th ed.): Articulations of the Pelvis (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain.

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Representative model, for educational purposes only.

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