Extensor Carpi Radialis Brevis Muscle Anatomy
The extensor carpi radialis brevis (ECRB), as its name indicates, is a shorter muscle than the extensor carpi radialis longus (ECRL) because it arises distally in the limb. It’s located within the superficial posterior compartment of the forearm.
The superficial posterior compartment of the forearm contains the following muscles:
- Brachioradialis,
- Extensor carpi radialis longus and brevis,
- Extensor digitorum,
- Extensor digiti minimi
- Extensor carpi ulnaris.
Extensor Carpi Radialis Brevis Muscle Anatomy
The extensor carpi radialis brevis (ECRB) originates from the lateral epicondyle of humerus (common extensor tendon).
It attaches adjacent to the ECRL in the hand (but to the base of the 3rd metacarpal rather than the 2nd). As it passes distally, it is covered by the ECRL. The ECRB and ECRL pass under the extensor retinaculum together within the tendinous sheath of the extensor carpi radiales. The extensor carpi radialis brevis shares a common synovial sheath with the extensor carpi radialis longus.
See Also: Forearm Muscles Anatomy & Function
It’s innervated directly by the radial nerve (C5- C8), or sometimes from its deep branch/posterior interosseous nerve.
The muscle is vascularized by the radial recurrent artery, radial artery and deep brachial artery (via its radial collateral branch).
The two muscles act together to various degrees, usually as synergists to other muscles. When the two muscles act by themselves, they abduct the hand as they extend it. Acting with the extensor carpi ulnaris, they extend the hand (the brevis is more involved in this action). Acting with the FCR, they produce pure abduction. Their synergistic action with the extensor carpi ulnaris is important in steadying the wrist during tight flexion of the medial four digits (clenching the fist), a function in which the longus is more active.
Origin | Lateral epicondyle of humerus (common extensor tendon) |
Insertion | Posterior aspect of base of the 3nd metacarpal bone |
Innervation | Radial nerve (C6, C7) |
Blood Supply | Radial artery |
Action | Wrist extension and wrist abduction (radial deviation) |
Researchers found the extensor carpi radialis brevis to originate from the fascia of the extensor digitorum communis rather than its usual origin on the lateral epicondyle. Another variant involves uniting the extensor carpi radialis brevis and extensor carpi radialis longus muscles.
In patients suffering from lateral epicondylitis or tennis elbow, the extensor carpi radialis brevis muscle is the most commonly affected.
References & More
- Clinically Oriented Anatomy – 8th Edition
- Clinical Anatomy by Regions, Richard S. Snell.
- William PL, Warwick R, Dyson M, Bannister LH. Gray’s Anatomy. 37. Edinburgh: Churchill Livingstone; 1989. The muscles of the fore arm; p. 622. [Google Scholar]
- Walkowski AD, Goldman EM. Anatomy, Shoulder and Upper Limb, Forearm Extensor Carpi Radialis Brevis Muscle. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed
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