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# Pisiform

The pisiform is the small pea-shaped wrist bone felt at the base of the palm on the little-finger side; it sits inside a wrist tendon.

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## What it is

A pea-sized bone in the flexor carpi ulnaris tendon, felt at the heel of the hand.

## What it does

One of the eight carpal bones that let the wrist bend and carry load to the forearm.

## Key points

- A sesamoid bone in the flexor carpi ulnaris tendon, which continues distally as the pisohamate and pisometacarpal ligaments
- With the hook of the hamate it bounds Guyon's canal, through which the ulnar nerve and ulnar artery enter the hand
- Attachment of the flexor retinaculum on the ulnar side and origin of the abductor digiti minimi

## Key facts

**Joints with**
Triquetrum only

**Landmarks**
Sesamoid in the FCU tendon; medial wall of Guyon's canal

## Relations

**Behind**
[Triquetrum](https://durgical.com/en/anatomy/triquetrum/), at the pisotriquetral joint

**Above**
[Flexor carpi ulnaris tendon](https://durgical.com/en/anatomy/flexor-carpi-ulnaris-tendon/), which ends in it

**Below**
[Pisiform ligaments](https://durgical.com/en/anatomy/pisohamate-and-pisometacarpal-ligaments/) to the hook of the [hamate](https://durgical.com/en/anatomy/hamate/) and the base of the [5th metacarpal](https://durgical.com/en/anatomy/5th-metacarpal/); origin of the abductor digiti minimi

**Lateral**
Guyon's canal with the [ulnar nerve](https://durgical.com/en/anatomy/ulnar-nerve/) and [ulnar artery](https://durgical.com/en/anatomy/ulnar-artery/), then the hook of the hamate

**In front**
Palmaris brevis and [skin](https://durgical.com/en/anatomy/skin/) of the hypothenar eminence

## How to find it

The easiest carpal bone to feel: a pea-sized knob at the base of the hypothenar eminence, on the distal wrist crease on the little-finger side. With the wrist relaxed in slight flexion it can be moved from side to side, and the flexor carpi ulnaris tendon is followed down to it.

## Examination

- Pisotriquetral grind: pressing and rolling the pisiform against the triquetrum reproduces pain in pisotriquetral arthritis or instability

## On imaging

Overlaps the triquetrum on the PA view; it is seen clear of other bones on a lateral view in slight supination or on a [carpal tunnel](https://durgical.com/en/anatomy/carpal-tunnel/) view.

## Clinical notes

- Ulnar nerve compression in Guyon's canal (for example in cyclists leaning on handlebars) weakens the intrinsic hand muscles, with or without numbness of the little finger
- A fall on the hypothenar eminence can fracture it; painful nonunion or arthritis may be treated by removing it
- Landmark for an ulnar nerve block at the wrist: just proximal to it, the nerve lies under the radial edge of the flexor carpi ulnaris tendon, with the ulnar artery on its radial side

## Development

The last carpal bone to ossify, around age 9–12, sometimes from more than one centre, which can mimic a fracture.

## Test yourself

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

## In which tendon is the pisiform a sesamoid bone?

The flexor carpi ulnaris tendon, which continues as the pisohamate and pisometacarpal ligaments.

## Which canal do the pisiform and the hook of the hamate bound, and what passes through it?

Guyon's canal, through which the ulnar nerve and ulnar artery enter the hand.

## Which is the last carpal bone to ossify?

The pisiform, around age 9–12, sometimes from more than one centre, which can mimic a fracture.

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

## Its names

**Official Latin (TA2)**
os pisiforme TA2 1254

**Official Spanish (DeCS)**
Hueso pisiforme

**English (TA2)**
Pisiform

## Related

- [Abductor digiti minimi](https://durgical.com/en/anatomy/abductor-digiti-minimi/)
- [FCU tendon](https://durgical.com/en/anatomy/flexor-carpi-ulnaris-tendon/)
- [Flexor carpi ulnaris](https://durgical.com/en/anatomy/flexor-carpi-ulnaris/)
- [Flexor retinaculum](https://durgical.com/en/anatomy/flexor-retinaculum/)
- [Pisiform ligaments](https://durgical.com/en/anatomy/pisohamate-and-pisometacarpal-ligaments/)
- [Wrist capsule](https://durgical.com/en/anatomy/wrist-joint-capsule/)
- [Wrist collateral ligaments](https://durgical.com/en/anatomy/radial-and-ulnar-collateral-ligaments-of-the-wrist/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Carpal Bones](https://www.ncbi.nlm.nih.gov/books/NBK535382/).

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Representative model, for educational purposes only.

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