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
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 facts
- Attaches
- 3rd dorsal compartment, turning around Lister's tubercle of the radius, to the base of the 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 and interosseous membrane its tendon runs in the 3rd dorsal compartment, turns sharply round Lister's tubercle, crosses over the ECRL and ECRB 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 and extensor indicis tendons in the 4th compartment
- Deep
- Lister's tubercle of the distal radius, its pulley; further on, the 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.
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
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Hand Extensor Pollicis Longus Muscle; Anatomy, Shoulder and Upper Limb: Hand Anatomical Snuff Box.
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.
