Extensor Carpi Radialis Brevis Anatomy

Origin: Humerus (lateral epicondyle via common forearm extensor tendon, Radial collateral ligament of elbow joint, Aponeurosis of muscle

Insertion: 3rd metacarpal bone (base of dorsal surface on radial side), 2nd metacarpal (occasionally)

Innervation: Cervical root(s): C7 and C8

Nerve: radial nerve (posterior interosseous branch)

Diagrams & Photos
  • Extensor Carpi Radialis Brevis muscle and tendon.
    Extensor Carpi Radialis Brevis muscle and tendon.
  • ECRB is seen inserting into the base of the second metacarpal after crossing under the EPL.
    ECRB is seen inserting into the base of the second metacarpal after crossing under the EPL.
Key Points
  • The ECRB is contained in the second extensor compartment of the wrist.
  • The ECRB is stronger than the extensor carpi ulnaris (ECU).
  • Intersection Syndrome is caused by inflammation in the area between the radial wrist extensors (ECRB&ECRL) and the thumb abductor and extensor (APL & EPB).
Anatomy References
Anatomic Abbreviations
Hand Surgery Resource Anatomy Diagnostic Guide (Chapter)