Common extensor tendon !
The common extensor tendon anchors the muscles that lift the wrist and fingers to the outer elbow; tennis elbow starts here.
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What it is
The shared tendon of the wrist and finger extensors on the outer bump of the elbow.
What it does
Anchors the muscles that lift the wrist and fingers; tennis elbow starts here.
Key facts
- Attaches
- Lateral epicondyle of the humerus to ECRB, extensor digitorum, extensor digiti minimi and ECU
- Function
- Shared origin of the forearm extensors; ECRB part degenerates in lateral epicondylitis (tennis elbow)
- Tight in
- Wrist flexion with the elbow straight
Relations
- Course
- Arises from the front of the lateral epicondyle; the extensor carpi radialis brevis part lies deepest, directly on the lateral elbow capsule, partly overlapped by the extensor carpi radialis longus and the extensor digitorum
- Deep
- Radial collateral ligament, annular ligament and lateral capsule over the radiocapitellar joint; the lateral ulnar collateral ligament (LUCL) runs just behind
- In front
- Brachioradialis and extensor carpi radialis longus from the supracondylar ridge; the radial nerve divides into its superficial and deep branches in front of the elbow
- Behind
- Anconeus, between the lateral epicondyle and the olecranon
- Below
- Supinator, which the posterior interosseous nerve enters under the arcade of Frohse
How to find it
With the elbow bent to 90° and the forearm pronated, the lateral epicondyle is the bony point on the outer elbow; the tendon is felt just in front of and a little distal to its tip. Tenderness here, rather than over the radial head or further down the forearm, points to the tendon.
Examination
- Cozen test: elbow bent, forearm pronated, fist made and wrist extended against resistance; pain at the lateral epicondyle suggests lateral epicondylitis
- Mill test: the elbow is straightened passively with the forearm pronated and the wrist flexed; lateral elbow pain from stretching the origin is positive
- Resisted middle finger extension (Maudsley test): pain at the lateral epicondyle is positive; also painful in radial tunnel syndrome
- Chair lift test: lifting a chair with the elbow straight and the palm down reproduces lateral elbow pain
On imaging
Ultrasound shows a thick, hypoechoic origin with tears, calcification or new vessels on Doppler. MRI shows high signal and tears at the ECRB origin and checks the lateral ulnar collateral ligament beneath. X-rays are usually normal, sometimes with calcification.
Common problems
- Tennis elbow (lateral epicondylitis): wear of the tendon, mostly the ECRB part, from repeated gripping and wrist lifting.
- Pain on the outer elbow when gripping, lifting a cup or shaking hands; common in people aged 35-55, not only tennis players.
How it is diagnosed
Tenderness on the outer elbow bump and pain when lifting the wrist or middle finger against resistance. Ultrasound or MRI if unclear.
Treatment
- Activity changes, a forearm strap, and stretching and strengthening exercises; most cases settle within a year.
- Injections are sometimes used; steroid injections give short-term relief only.
- Surgery to clean out the damaged tendon when months of treatment fail.
Clinical notes
- Excessive surgical release or repeated corticosteroid injections can damage the LUCL and lead to posterolateral rotatory instability
- Radial tunnel syndrome: pain is maximal a few centimetres distal, over the supinator, with pain on resisted supination
- Lateral approaches to the elbow (Kocher, Kaplan) pass through or beside the extensor origin; pronating the forearm moves the posterior interosseous nerve away from the field
Anatomical variants
- The extensor group often shows extra bellies and doubled or missing tendon slips
Development
Its bony anchor, the lateral epicondyle, is the last of the six elbow ossification centres to appear (CRITOE order, around 11 years; ages vary between texts); before that the origin lies on cartilage that is invisible on X-rays.
Test yourself
Think of the answer, then tap the question to see it.
Which muscles share the common extensor tendon on the lateral epicondyle?
ECRB, extensor digitorum, extensor digiti minimi and ECU.
What is the pathology of lateral epicondylitis in the common extensor tendon?
A degenerative tendinosis, not an inflammation, starting on the deep surface of the ECRB origin.
What is the Cozen test?
Elbow bent, forearm pronated, fist made and wrist extended against resistance; pain at the lateral epicondyle suggests lateral epicondylitis.
What condition mimics lateral epicondylitis, with maximal tenderness a few centimetres distal?
Radial tunnel syndrome, with tenderness over the supinator and pain on resisted supination.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- tendo extensorius communis TA2 2498
- Official Spanish (DeCS)
- Tendón común de los extensores
- English (TA2)
- Common extensor tendon
- Also called
- common extensor origin
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Wrist Extensor Muscles.
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Representative model, for educational purposes only.
