Muscle guide · Arms
Also called forearm extensors, tennis elbow muscles
The extensors are the muscles on the back of the forearm. Many start from a shared tendon on the bony bump on the outside of the elbow, and their tendons run across the back of the wrist to the hand and fingers.
They lift the wrist and straighten the fingers, and they hold the wrist slightly back whenever you grip, so the finger flexors can squeeze hard. That is why gripping aggravates tennis elbow.
Source 1
| Part | Starts at | Attaches to | What it does |
|---|---|---|---|
| Extensor carpi radialis longus and brevis | Just above and on the outer elbow bump | Bases of the index and middle finger bones | Lift the wrist and tilt it toward the thumb; steady it in a power grip |
| Extensor carpi ulnaris | Outer elbow bump and the ulna | Base of the little finger bone | Lifts the wrist and tilts it toward the little finger |
| Extensor digitorum and digiti minimi | Outer elbow bump | The backs of the fingers | Straighten the fingers |
| Supinator and the deep thumb extensors | Outer elbow and back of the forearm bones | Radius; thumb and index finger | Turn the palm up; straighten and lift the thumb and index finger |
Source 1
In a small trial of chronic tennis elbow, adding eccentric wrist extension (twisting and slowly releasing a flexible bar) to usual physiotherapy improved function by 76% against 13%.
With the elbow straight and palm down, gently bend the wrist down. Forearm stretching is part of standard tennis elbow care.
A degenerative tendinopathy, usually of the extensor carpi radialis brevis, where it starts on the outer elbow. It affects about 1 to 3% of people, most often in their 30s to 50s; gripping, shaking hands and turning a wrench hurt.
80 to 90% recover within 1 to 2 years and 80 to 95% without surgery, though recurrence is common. Surgery is considered after 6 to 12 months of good care.
Each grade rates the evidence for the correction.
Tennis players are only about 10% of cases; computer work, manual trades, cooking and playing instruments are common causes.
Clinical guidelines now call it a tendinopathy, not an inflammation, and both the NHS and StatPearls recommend strengthening as part of treatment.
They lift the wrist and straighten the fingers, and hold the wrist steady so you can grip hard.
Slow eccentric wrist extension, such as twisting and slowly releasing a flexible bar, improved function far more than usual care alone in a small trial.
80 to 90% of people recover within 1 to 2 years, most without surgery, though it can come back.
Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.
