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MuscleForearm & handsuperficialDraft

Wrist extensors

Group of muscles on the back of the forearm, mostly arising from the common extensor tendon at the lateral epicondyle, that straighten and lift the wrist and fingers.

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Origin
  • Common extensor tendon on the lateral epicondyle of the humerus (extensor carpi radialis brevis, extensor digitorum, extensor carpi ulnaris)
  • Lower third of the lateral supracondylar ridge of the humerus (extensor carpi radialis longus)
  • Posterior border of the ulna (extensor carpi ulnaris)
Insertion
  • Back of the base of the 2nd metacarpal (extensor carpi radialis longus)
  • Back of the base of the 3rd metacarpal (extensor carpi radialis brevis)
  • Base of the 5th metacarpal (extensor carpi ulnaris)
  • Extensor expansions of the four fingers (extensor digitorum)
Action
  • All members: extend the wrist
  • Extensor carpi radialis longus and brevis: also abduct the wrist (tilt it towards the thumb)
  • Extensor carpi ulnaris: also adducts the wrist (tilts it towards the little finger)
  • Extensor digitorum: extends the four fingers
NerveRadial nerve and its deep branch (posterior interosseous nerve) (C6–C8)
MembersExtensor carpi radialis longus, Extensor carpi radialis brevis, Extensor carpi ulnaris, Extensor digitorum

Palpation

  1. Client supine or seated with the forearm palm down and supported.
  2. Find the lateral epicondyle and place your fingers just below it on the back of the forearm.
  3. Feel the firm muscle mass running down the back and outer side of the forearm towards the back of the wrist.
  4. Ask the client to make a loose fist and lift the back of the hand against light resistance; the whole mass firms.

Landmarks: Lateral epicondyle of humerus · Olecranon

The wrist extensors form the firm muscle on the back and outer side of the forearm. Three of them share the common extensor tendon on the Lateral epicondyle of humerus, along with a small muscle for the little finger (extensor digiti minimi). Extensor carpi radialis longus starts a little higher, on the ridge above the epicondyle, just behind Brachioradialis.

These muscles hold the wrist steady every time the hand grips, so they work hard in typing, mouse use, racquet sports and massage. Clients who have been told they have “tennis elbow” often report tenderness just below the lateral epicondyle. In a relaxation routine, Effleurage and Petrissage from wrist to elbow, followed by a gentle wrist-flexion stretch, suit this area well.

The extensors work against the Wrist flexors. Extensors are on the back of the forearm and start at the lateral epicondyle. Flexors are on the palm side and start at the Medial epicondyle of humerus. Supinator lies deep to the top of the extensor mass.

Techniques

  • Effleurage — Long, gliding strokes with the whole palm that spread the medium, warm the tissue and link the other strokes together.
  • Petrissage — Kneading strokes that compress, lift and squeeze the muscle away from the bone, working the tissue between the hands.
  • Circular friction — Small circles made with the finger or thumb pads that move the skin over the deeper tissue without sliding, to work a specific spot.
  • Compression — Pressing straight down into a muscle with the palm, fist or forearm, holding briefly, then releasing and moving on.
  • Passive stretching — The therapist gently moves a relaxed limb to lengthen a muscle to a point of mild stretch and holds it there, with no effort from the client.

Opposes

  • Wrist flexors — Group of forearm muscles on the palm side, most arising from the common flexor tendon at the medial epicondyle, that bend the wrist and fingers.

Used in routines

Sources

  1. Wikipedia: Common extensor tendon
  2. Wikipedia: Posterior compartment of the forearm
  3. Gray's Anatomy of the Human Body (1918), Myology 7e: The Muscles and Fasciae of the Forearm (Public domain. Used for attachments, actions and nerve root levels.)