[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/) › Wrist extensor tendons [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Wrist extensor tendons The wrist extensor tendons run across the back of the wrist; they hold the wrist back so the fingers can grip strongly. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=wrist_extensor_tendons&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The tendons that lift the wrist, on the back of the wrist at each side. ## What it does Hold the wrist back so the fingers can grip strongly. ## Key points - ECRB, inserting nearest the centre of the wrist, is the purest wrist extensor; ECRL also tilts the wrist radially and ECU ulnarly - The ECU is held in its groove by a subsheath that is part of the TFCC; a tear lets it snap out of the groove in supination - In [posterior interosseous nerve](https://durgical.com/en/anatomy/posterior-interosseous-nerve/) palsy the wrist still extends but drifts radially: ECRL (supplied above the elbow) works while ECU does not ## Key facts **Attaches** ECRL and ECRB in the 2nd dorsal compartment to the bases of the 2nd and 3rd metacarpals; ECU in the 6th compartment, in the groove of the ulna, to the base of the [5th metacarpal](https://durgical.com/en/anatomy/5th-metacarpal/) **Function** Extend the wrist and steady it for grip; the ECU also steadies the ulnar side; intersection syndrome where the thumb tendons cross the radial extensors **Tight in** Wrist flexion with the elbow straight ## Relations **Course** [ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/) and [ECRB](https://durgical.com/en/anatomy/extensor-carpi-radialis-brevis/) run down the radial side of the forearm under the APL and EPB, through the 2nd compartment, and are crossed by the EPL; the ECU runs along the back of the [ulna](https://durgical.com/en/anatomy/ulna/) to the 6th compartment **Deep** ECRL and ECRB on the back of the distal [radius](https://durgical.com/en/anatomy/radius/), radial to Lister's tubercle; ECU in the groove beside the ulnar styloid, over the [TFCC](https://durgical.com/en/anatomy/triangular-fibrocartilage-complex/) **Superficial** [Extensor retinaculum](https://durgical.com/en/anatomy/extensor-retinaculum-of-the-wrist/); branches of the [superficial radial nerve](https://durgical.com/en/anatomy/superficial-branch-of-the-radial-nerve/) over ECRL and ECRB, the dorsal branch of the [ulnar nerve](https://durgical.com/en/anatomy/ulnar-nerve/) over ECU **Lateral** [Brachioradialis tendon](https://durgical.com/en/anatomy/brachioradialis-tendon/) and the 1st compartment (APL and EPB), radial to ECRL **Medial** [Flexor carpi ulnaris](https://durgical.com/en/anatomy/flexor-carpi-ulnaris/), round the ulnar border from the ECU, the most ulnar tendon on the back of the wrist ## How to find it Making a tight fist with the wrist extended, ECRL and ECRB are felt on the back of the wrist just radial to Lister's tubercle, running to the bases of the 2nd and 3rd metacarpals; the ECU is felt in the groove next to the ulnar head, best with the wrist tilted ulnarly. ## Examination - ECU synergy test: with the forearm supinated, resisted radial movement of the thumb makes the ECU contract; pain along it suggests ECU tendinitis rather than a problem inside the joint - Snapping of the ECU when the forearm turns from pronation to supination with the wrist tilted ulnarly suggests subluxation - Resisted wrist extension: pain locates tendinopathy; weakness of all three with wrist drop points to the [radial nerve](https://durgical.com/en/anatomy/radial-nerve/) above the elbow ## On imaging Dynamic ultrasound with forearm rotation shows ECU subluxation out of its groove; MRI shows tendinosis, split tears of the ECU and subsheath injury. X-rays show a carpal boss at the 2nd and 3rd carpometacarpal joints. ## Clinical notes - ECU subsheath tears happen in racket and club sports with forced supination and ulnar deviation - Carpal boss: a bony bump at the base of the 2nd and 3rd metacarpals near the ECRL and ECRB insertions, sometimes with a bursa or ganglion - Active wrist extension (ECRL, ECRB) powers tenodesis grasp in C6 tetraplegia ## Anatomical variants - Extra radial wrist extensor bellies or slips, and doubled tendons or cross-slips between ECRL and ECRB, are common ## Memory aid Tendons per dorsal compartment, from radial to ulnar: 2-2-1-2-1-1 (APL/EPB, ECRL/ECRB, EPL, ED/EI, EDM, ECU). ## Test yourself Think of the answer, then tap the question to see it. ## Where do the wrist extensor tendons insert? ECRL and ECRB (2nd compartment) on the bases of the 2nd and 3rd metacarpals; ECU (6th compartment) on the base of the 5th. ## Which wrist extensor tendon is the purest wrist extensor? ECRB, which inserts nearest the centre of the wrist; ECRL also tilts radially and ECU ulnarly. ## Why does the wrist drift radially in posterior interosseous nerve palsy? ECRL, supplied above the elbow, still works while the ECU does not. ## What holds the ECU tendon in its groove, and what happens when it tears? A subsheath that is part of the TFCC; a tear lets the ECU snap out of the groove in supination. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/wrist-extensor-tendons/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** tendines musculorum extensorum carpi TA2 2497 **Official Spanish (DeCS)** Tendones de los músculos extensores del carpo **English (TA2)** Wrist extensor tendons ## Related - [TFCC](https://durgical.com/en/anatomy/triangular-fibrocartilage-complex/) - [2nd metacarpal](https://durgical.com/en/anatomy/2nd-metacarpal/) - [3rd metacarpal](https://durgical.com/en/anatomy/3rd-metacarpal/) - [Radius](https://durgical.com/en/anatomy/radius/) - [Trapezoid](https://durgical.com/en/anatomy/trapezoid/) - [Triquetrum](https://durgical.com/en/anatomy/triquetrum/) - [Ulna](https://durgical.com/en/anatomy/ulna/) - [ECRL](https://durgical.com/en/anatomy/extensor-carpi-radialis-longus/) Sources: Terminologia Anatomica (TA2); [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/wrist-extensor-tendons/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/wrist-extensor-tendons/