Flexor carpi radialis brevis vel profundus

Last revised by Dr Joachim Feger on 06 Sep 2021

The flexor carpi radialis brevis (FCRB) vel profundus muscle is an accessory muscle of the forearm and wrist and a normal anatomical variant.

The flexor carpi radialis brevis vel profundus muscle has been found in 2-8% of anatomical dissections 1-3.

The flexor carpi radialis brevis vel profundus muscle originates from the volar radial surface distal and radial to the flexor pollicis longus and runs deep to the flexor carpi radialis muscle 1-4. It might show several variant accessory fibers from other anatomical structures of the forearm 1. It traverses the pronator quadratus superficially and runs deep to the flexor retinaculum through the osteofibrous tunnel of the flexor carpi radialis and inserts to the radial carpus and to the bases of the second to fourth metacarpophalangeal joints 1-4.

The flexor carpi radialis brevis vel profundus can have accessory fibers from various sources and might appear as bi capitate muscle including 1:

Variations in tendon insertion include several radial-sided carpal bones 1.

The flexor carpi radialis brevis vel profundus muscle can be nicely visualized on MRI of the wrist on the radial side deep to flexor carpi radialis and flexor pollicis longus tendons and superficial to the radial insertion of the pronator quadratus muscle 4.

The muscle was first described by M. Fano in 1851 under the name ‘Radiocarpien’. The name flexor carpi radialis brevis vel profundus was given to the muscle by John Wood in 1867 1,2,5. Anatole-Félix le Double described several cases of the muscle in 1897 and called it ‘Court Radial anterieur’ 6.

Surgeons might come across the flexor carpi radialis brevis vel profundus muscle during volar plate fixation of the distal radius 2,3. It might be confused with a pathologic condition on imaging such as a tumor 4.

The flexor carpi radialis brevis vel profundus muscle has been implicated in the following clinical conditions 2-4:

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.