Extensor Pollicis Brevis
Original Editor - Oyemi Sillo
Top Contributors - Oyemi Sillo
The extensor pollicis brevis originates from the lower third of the posterior surface of the radius and the interosseous membrane.
It inserts on the base of the proximal phalanx of the thumb.
The EPB is supplied by the posterior interosseous nerve (C7 & C8), the continuation of the deep branch of the radial nerve.
The EPB is supplied by the posterior interosseous artery, which originates from the common interosseous branch of the ulnar artery.
The tendons of the EPB and the Abductor Pollicis Longus (APL) are enclosed in a common sheath at the dorsum of the wrist. Forceful or repetitive movements of the thumb and wrist can increase the friction between both tendons, causing inflammation in their shared tendon. This condition, known as De Quervain's Tenosynovitis, causes pain in the radial aspect of the wrist that radiates to the proximal part of the forearm.
De Quervain's Tenosynovitis can be assessed with a test called Finkelstein Test: the examiner grasps the patient's thumb with one hand and holds the patient's forearm in neutral position with the other hand. The examiner then pulls on the patient's thumb longitudinally with a slight ulnar deviation at the wrist. Increased pain at the radial styloid process indicates a positive test.
Physiotherapy treatment for De Quervain's Tenosynovitis involves:
- Immobilization of the thumb and wrists with splints, to give the tendons time to heal.
- Myofascial release, soft-tissue massage and ice packs, to reduce pain.
- Muscle strengthening and stretching, to improve mobility.
- Ergonomic education, joint protection techniques
Medical and surgical treatments include:
- Corticosteroid injections
- Surgical release of the tendon sheath
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