[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/) › APL and EPB tendons [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # APL and EPB tendons The abductor pollicis longus and extensor pollicis brevis tendons run along the thumb side of the wrist; de Quervain tenosynovitis inflames them. Official name: Abductor pollicis longus and extensor pollicis brevis tendons [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=apl_epb_tendons&side=r) Opens in the Durgical app, no sign-up needed. ## What it is Two tendons side by side in the first tunnel on the thumb side of the wrist. ## What it does Move the thumb out and back; they form the front edge of the 'snuffbox'. ## Key points - A septum often divides the 1st compartment and gives the EPB its own tunnel; leaving it closed at surgery is a classic cause of persistent de Quervain pain - Finkelstein test (examiner pulls the thumb and tilts the wrist ulnarly) and Eichhoff test (thumb in the fist) differ; Eichhoff gives more false positives - Intersection syndrome is a separate problem a few centimetres above the wrist, where these tendons cross over ECRL and ECRB - Branches of the superficial radial nerve cross over the compartment and are at risk in de Quervain release ## Key facts **Attaches** 1st dorsal compartment over the radial styloid: APL to the base of the [1st metacarpal](https://durgical.com/en/anatomy/1st-metacarpal/) (often in several slips), EPB to the base of the thumb's proximal phalanx **Function** Abduct and extend the thumb; front border of the anatomical snuffbox; de Quervain tenosynovitis (Finkelstein test) **Tight in** Thumb flexed into the palm with ulnar deviation of the wrist ## Relations **Course** They wind obliquely from the back of the forearm over the [ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/) and [ECRB](https://durgical.com/en/anatomy/extensor-carpi-radialis-brevis/) tendons, pass through the 1st dorsal compartment over the radial styloid and diverge to the thumb **Superficial** [Extensor retinaculum](https://durgical.com/en/anatomy/extensor-retinaculum-of-the-wrist/) and the branches of the [superficial radial nerve](https://durgical.com/en/anatomy/superficial-branch-of-the-radial-nerve/); the [cephalic vein](https://durgical.com/en/anatomy/cephalic-vein/) begins nearby **Deep** Radial styloid and, just beyond it, the [radial artery](https://durgical.com/en/anatomy/radial-artery/) as it enters the anatomical snuffbox **Behind** [EPL tendon](https://durgical.com/en/anatomy/extensor-pollicis-longus-tendon/), the opposite border of the anatomical snuffbox ## How to find it With the thumb extended and pulled back (hitchhiker position), the tendons form the palmar border of the anatomical snuffbox; they are followed back over the radial styloid, where tenderness and swelling point to de Quervain tenosynovitis. ## Examination - Finkelstein test: the examiner grasps the thumb and tilts the wrist ulnarly; sharp pain over the radial styloid suggests de Quervain tenosynovitis - Eichhoff test: the fist is closed over the thumb and the wrist tilted ulnarly; pain over the radial styloid is positive, but many normal wrists also hurt - Pain and creaking (crepitus) a few centimetres above the wrist on wrist movement point to intersection syndrome instead ## On imaging Ultrasound shows thick tendons and sheath, fluid and the septum dividing the compartment, and is used to guide injections; it also shows the swelling where they cross the radial wrist extensors in intersection syndrome. ## Common problems - De Quervain's tenosynovitis: the tendons and their sheath swell in the first tunnel, causing pain at the thumb side of the wrist. - Common in new parents lifting a baby and with repeated thumb use. ## How it is diagnosed Pain when the thumb is tucked into the fist and the wrist is tilted toward the little finger (Finkelstein-type test). ## Treatment - Thumb splint, activity changes and a steroid injection, which helps most people. - Surgical release of the first tunnel's roof, protecting the superficial radial nerve. ## Clinical notes - De Quervain release: the superficial radial nerve branches are protected and any separate EPB tunnel is opened - Intersection syndrome affects rowers, paddlers and weightlifters, from friction where the tendons cross - Thumb basal joint arthritis and [scaphoid](https://durgical.com/en/anatomy/scaphoid/) fracture cause pain nearby; the grind test and snuffbox tenderness help tell them apart ## Anatomical variants - The APL usually has two or more slips; extra slips of both tendons are common - A septum divides the 1st compartment in many wrists, more often in people with de Quervain tenosynovitis ## Related conditions - [De Quervain tenosynovitis](https://durgical.com/en/conditions/de-quervain-tenosynovitis/) ## Test yourself Think of the answer, then tap the question to see it. ## Where do the APL and EPB tendons insert? APL on the base of the 1st metacarpal (often in several slips); EPB on the base of the thumb's proximal phalanx. ## What classic cause of persistent de Quervain pain involves the EPB tendon? A septum giving the EPB its own tunnel in the 1st compartment, left unopened at surgery. ## Which nerve branches are at risk in de Quervain release of the APL and EPB tendons? Branches of the superficial radial nerve, which cross over the 1st compartment. ## Which border of the anatomical snuffbox do the APL and EPB tendons form? The front (palmar-radial) border; the EPL forms the back border. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/abductor-pollicis-longus-and-extensor-pollicis-brevis-tendons/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** tendines musculorum abductoris longi et extensoris brevis pollicis TA2 2517 **Official Spanish (DeCS)** Tendones de los músculos abductor largo y extensor corto del pulgar **English (TA2)** Abductor pollicis longus and extensor pollicis brevis tendons ## Related - [1st compartment sheath](https://durgical.com/en/anatomy/tendon-sheath-of-the-1st-dorsal-compartment/) - [Superficial radial nerve](https://durgical.com/en/anatomy/superficial-branch-of-the-radial-nerve/) - [Radial artery](https://durgical.com/en/anatomy/radial-artery/) - [1st metacarpal](https://durgical.com/en/anatomy/1st-metacarpal/) - [Proximal phalanx, thumb](https://durgical.com/en/anatomy/proximal-phalanx-of-the-thumb/) - [Radius](https://durgical.com/en/anatomy/radius/) - [APL](https://durgical.com/en/anatomy/abductor-pollicis-longus/) - [EPB](https://durgical.com/en/anatomy/extensor-pollicis-brevis/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb: Hand Anatomical Snuff Box](https://www.ncbi.nlm.nih.gov/books/NBK482228/); [Anatomy, Shoulder and Upper Limb, Wrist Extensor Muscles](https://www.ncbi.nlm.nih.gov/books/NBK534805/). ## **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/abductor-pollicis-longus-and-extensor-pollicis-brevis-tendons/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/abductor-pollicis-longus-and-extensor-pollicis-brevis-tendons/