Flexor carpi radialis brevis muscle, a rare anomalous muscle of the forearm; a case report and literature review.

The flexor carpi radialis brevis (FCRB) is a rare abnormal muscle of the distal forearm or wrist. Its incidence varies in different reports, which oscillating between 2-8%. This paper reports a case of FCRB found in the anatomy of the forearm. The abnormal muscle, which started from the facies volaris distal radii, occupies the terminus of pronator quadratus, and was observed with dysplasia in the pronator quadratus. We also reviewed the literature on FCRB anatomy, especially the surgical exposure of distal radius fractures and the clinical symptoms caused by FCRB. Knowledge of the anomalous muscles of the forearm and wrist can highly improve clinician's understanding of the disease during surgery and imaging examination, and reduce unnecessary trauma caused by misdiagnosis.