A Flexor Carpi Radialis Brevis Muscle With an Anomalous Origin on the Distal Radius

This report describes an anomalous muscle on the volar aspect of the wrist alongside an underdeveloped pronator quadratus. Identified during cadaveric dissection, the longitudinally oriented muscle originated on the distal radial metaphysis, a location occupied typically by the insertion of the pronator quadratus. The aberrant muscle formed a tendon distally, which inserted along with the flexor carpi radialis tendon at the base of the index metacarpal.