Flexor carpi radialis brevis vel profundus
Citation, DOI and article data
The flexor carpi radialis brevis vel profundus muscle has been found in 2-8% of anatomical dissections 1-3.
- origin: anterior surface of the lower third of the distal radius
- insertion: second to fourth metacarpal base and the capitate or other radial sided carpal bones
- innervation: anterior interosseous nerve
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:
- pronator teres muscle
- antebrachial aponeurosis
- flexor pollicis longus muscle
- interosseous membrane
- the anterior surface of the ulna
- distal humerus
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.
History and etymology
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:
- 1. Carleton A. Flexor Carpi Radialis Brevis Vel Profundus. J Anat. 1935;69(Pt 2):292-3. PMC1249108
- 2. Lee Y, Song S, Sur Y, Ahn C. Flexor Carpi Radialis Brevis: An Unusual Anomalous Muscle of the Wrist. Clin Orthop Surg. 2014;6(3):361-4. doi:10.4055/cios.2014.6.3.361
- 3. Andring N, Kennedy S, Iannuzzi N. Anomalous Forearm Muscles and Their Clinical Relevance. J Hand Surg Am. 2018;43(5):455-463. doi:10.1016/j.jhsa.2018.02.028
- 4. Sookur P, Naraghi A, Bleakney R, Jalan R, Chan O, White L. Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation. Radiographics. 2008;28(2):481-99. doi:10.1148/rg.282075064
- 5. Wood J. On Human Muscular Variations and Their Relation to Comparative Anatomy. J Anat Physiol. 1867;1(1):44-59. PMC1318528
- 6. Anatole-Félix le Double. Traité Des Variations Du Système Musculaire De L'Homme Et De Leur Signification Au Point De Vue De L'Anthropologie Zoologique, Vol. 2 (Classic Reprint). (2016-08-04) ISBN: 9781333171803
- 7. Hongsmatip P, Smitaman E, Delgado G, Resnick D. Flexor Carpi Radialis Brevis: A Rare Accessory Muscle Presenting as an Intersection Syndrome of the Wrist. Skeletal Radiol. 2018;48(3):457-460. doi:10.1007/s00256-018-3034-1