[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › EPL tendon [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # EPL tendon The extensor pollicis longus tendon runs on the back of the wrist to the thumb tip; it pulls the thumb back and can rupture after a wrist fracture. Official name: Extensor pollicis longus tendon [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=epl_tendon&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The thumb's long extensor tendon, which turns around a bump on the radius (Lister's tubercle). ## What it does Lifts the thumb back; it can wear through after a wrist fracture. ## Key points - Rupture after a distal radius fracture typically follows an undisplaced fracture by weeks; the intact retinaculum leaves a tight, poorly supplied tunnel - The retropulsion test is the reliable one: the thenar muscles can still extend the thumb IP through the hood after an EPL rupture - Dorsal screw tips from a volar plate can protrude into the 3rd compartment and fray it ## Key facts **Attaches** 3rd dorsal compartment, turning around Lister's tubercle of the radius, to the base of the [distal phalanx of the thumb](https://durgical.com/en/anatomy/distal-phalanx-of-the-thumb/) **Function** Extends the thumb's interphalangeal joint and lifts the thumb back; back border of the anatomical snuffbox; can rupture weeks after a distal radius fracture **Tight in** Thumb flexion with wrist flexion ## Relations **Course** From the back of the [ulna](https://durgical.com/en/anatomy/ulna/) and interosseous membrane its tendon runs in the 3rd dorsal compartment, turns sharply round Lister's tubercle, crosses over the [ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/) and [ECRB](https://durgical.com/en/anatomy/extensor-carpi-radialis-brevis/) tendons and runs along the back of the thumb **Lateral** ECRL and ECRB tendons in the 2nd compartment at the wrist, which it then crosses superficially **Medial** [Extensor digitorum](https://durgical.com/en/anatomy/extensor-digitorum/) and [extensor indicis](https://durgical.com/en/anatomy/extensor-indicis/) tendons in the 4th compartment **Deep** Lister's tubercle of the distal [radius](https://durgical.com/en/anatomy/radius/), its pulley; further on, the [radial artery](https://durgical.com/en/anatomy/radial-artery/) crossing the floor of the anatomical snuffbox ## How to find it With the palm flat on a table and the thumb lifted upward, the tendon stands out as the dorsal border of the anatomical snuffbox; it is followed back to Lister's tubercle, a bump on the back of the distal radius in line with the third metacarpal. ## Examination - Retropulsion test: the hand flat on a table and the thumb lifted off it; inability to lift it means an EPL rupture - Thumb IP extension alone is not proof of an intact tendon, since the thenar muscles can extend it through the hood ## On imaging Ultrasound shows the gap and the retracted ends. Dorsal screws standing proud of the dorsal cortex are hard to see on standard views; a dorsal tangential (skyline) view or CT shows them better. ## Common problems - Can wear through and rupture weeks after a distal radius fracture, even a minor one, or rub on a screw tip. - Then the thumb cannot lift off a flat table. ## How it is diagnosed Exam: the patient cannot lift the thumb up off the table. Ultrasound shows the gap. ## Treatment - Tendon transfer (usually extensor indicis) or graft to restore thumb lifting. - Correct screw length during wrist plating helps prevent it. ## Clinical notes - Attrition rupture also happens over Lister's tubercle in rheumatoid arthritis - Transfer of the extensor indicis to the EPL is the usual reconstruction, as the ends are frayed and retracted - Dorsal approaches to the wrist often open the 3rd compartment and move the EPL radially out of the way ## Anatomical variants - Rare duplicated or accessory EPL tendons and extra slips are described ## Test yourself Think of the answer, then tap the question to see it. ## Around which landmark does the EPL tendon turn? Lister's tubercle of the radius, in the 3rd dorsal compartment. ## Why does the EPL tendon rupture weeks after an undisplaced distal radius fracture? The intact retinaculum leaves a tight, poorly supplied tunnel at Lister's tubercle, where the tendon frays. ## Which test reliably shows an EPL tendon rupture? The retropulsion test: hand flat, thumb cannot be lifted off the table; IP extension alone is unreliable, as thenar muscles can extend it. ## What is the usual reconstruction for a ruptured EPL tendon? Transfer of the extensor indicis to the EPL, since the ends are frayed and retracted. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/extensor-pollicis-longus-tendon/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** tendo musculi extensoris longi pollicis TA2 2516 **Official Spanish (DeCS)** Tendón del músculo extensor largo del pulgar **English (TA2)** Extensor pollicis longus tendon ## Related - [Radius](https://durgical.com/en/anatomy/radius/) - [Extensor tendon sheaths](https://durgical.com/en/anatomy/wrist-extensor-tendon-sheaths/) - [EPL](https://durgical.com/en/anatomy/extensor-pollicis-longus/) - [1st metacarpal](https://durgical.com/en/anatomy/1st-metacarpal/) - [Distal phalanx, thumb](https://durgical.com/en/anatomy/distal-phalanx-of-the-thumb/) - [Proximal phalanx, thumb](https://durgical.com/en/anatomy/proximal-phalanx-of-the-thumb/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Hand Extensor Pollicis Longus Muscle](https://www.ncbi.nlm.nih.gov/books/NBK544294/); [Anatomy, Shoulder and Upper Limb: Hand Anatomical Snuff Box](https://www.ncbi.nlm.nih.gov/books/NBK482228/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/extensor-pollicis-longus-tendon/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/extensor-pollicis-longus-tendon/