Common flexor tendon !
The common flexor tendon anchors the muscles that bend the wrist and fingers to the inner elbow; golfer's elbow affects it.
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What it is
The shared tendon of the forearm flexors and pronator on the inner bump of the elbow.
What it does
Anchors the muscles that bend the wrist and fingers and turn the palm down; it also shields the UCL.
Key facts
- Attaches
- Medial epicondyle of the humerus to pronator teres, FCR, palmaris longus, FDS and FCU
- Function
- Shared origin of the forearm flexors; site of medial epicondylitis (golfer's elbow)
- Tight in
- Wrist extension with the elbow straight
Relations
- Course
- From the front of the medial epicondyle, fibres pass down into the superficial forearm flexors; septa between the muscles give them extra origin
- Deep
- Anterior bundle of the ulnar collateral ligament (UCL) and the medial elbow capsule
- Behind
- Ulnar nerve in the cubital tunnel behind the medial epicondyle; it reaches the forearm by passing between the humeral and ulnar heads of flexor carpi ulnaris
- Lateral
- Brachial artery and median nerve in the cubital fossa; the median nerve passes between the two heads of the pronator teres
- Superficial
- Branches of the medial antebrachial cutaneous nerve, crossing near the epicondyle
How to find it
The medial epicondyle is the prominent bump on the inner elbow; the tendon is felt just in front of and distal to it and tightens when the wrist is flexed against resistance. The ulnar nerve can be rolled in the groove just behind the epicondyle.
Examination
- Golfer's elbow test: the elbow is straightened passively with the forearm supinated and the wrist extended; pain at the medial epicondyle suggests medial epicondylitis
- Resisted wrist flexion and resisted pronation: pain at the medial epicondyle points to the tendon
- Moving valgus stress test: valgus applied while the elbow is flexed and extended; pain at mid-range (about 70°–120°) suggests a UCL injury rather than tendinopathy
- Tinel sign at the cubital tunnel and the elbow flexion test: tingling in the ring and little fingers suggests coexisting ulnar nerve irritation
On imaging
Ultrasound and MRI show a thick, hypoechoic or high-signal origin with or without tears; MRI also shows the UCL beneath and changes around the ulnar nerve. X-rays may show calcification or traction spurs.
Common problems
- Golfer's elbow (medial epicondylitis): wear of the tendon from repeated gripping, throwing or wrist bending.
- Inner elbow pain; may come with ulnar nerve irritation.
How it is diagnosed
Tenderness on the inner elbow bump and pain when bending the wrist or turning the palm down against resistance. Exam of the UCL and ulnar nerve.
Treatment
- Activity changes, stretching and strengthening; most cases settle with time.
- Surgery to clean out the damaged tendon when months of treatment fail.
Clinical notes
- In children the tendon pulls on the medial epicondyle apophysis: repeated throwing irritates it ('Little League elbow'), and in elbow dislocations the avulsed epicondyle can be trapped in the joint
- The ulnar nerve and the medial antebrachial cutaneous nerve are at risk in surgery at the origin
- In throwers, flexor-pronator strains and UCL tears can coexist and must be told apart
Anatomical variants
- The palmaris longus, one of its muscles, is often absent (up to about a quarter of people in some series)
Development
The medial epicondyle apophysis appears early (around 5–7 years in the CRITOE order) but is the last elbow centre to fuse, in late adolescence; until then the flexor-pronator pull acts across an open physis.
Memory aid
Heel of the opposite hand on the medial epicondyle, fingers spread down the forearm: thumb pronator teres, index flexor carpi radialis, middle palmaris longus, ring flexor carpi ulnaris; the FDS lies deep to them.
Test yourself
Think of the answer, then tap the question to see it.
Which muscles arise from the common flexor tendon on the medial epicondyle?
Pronator teres, FCR, palmaris longus, FDS and FCU.
Which origins does medial epicondylitis mainly involve?
The pronator teres and flexor carpi radialis origins; it is much less common than lateral epicondylitis.
Why do ulnar nerve symptoms often accompany medial epicondylitis?
The ulnar nerve runs just behind the common flexor tendon.
How does the common flexor tendon relate to the elbow's ulnar collateral ligament?
The flexor-pronator mass lies over the UCL and helps resist valgus stress in throwers; strains and UCL tears can coexist.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- tendo flexorius communis TA2 2489
- Official Spanish (DeCS)
- Tendón común de los flexores
- English (TA2)
- Common flexor tendon
- Also called
- common flexor origin · flexor-pronator origin
Related
- Ulnar nerve
- UCL (elbow)
- Humerus
- Pronator teres
- Flexor carpi radialis
- Palmaris longus
- FDS
- Flexor carpi ulnaris
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Forearm Muscles; Anatomy, Shoulder and Upper Limb, Forearm Compartments.
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Representative model, for educational purposes only.
