An anomalous case of the flexor carpi radialis with an excessive muscular bundle.

A variation of the flexor carpi radialis with an excessive muscular bundle was found on the right forearm of a Japanese male cadaver. The flexor carpi radialis had two heads, medial one arising from the medial epicondyle of the humerus, and the other, a variant excessive muscular bundle, arising from the bicipital aponeurosis deep at the medial edge of the tendon of biceps brachii. There was also a muscular slip between the pronator teres and lateral head of flexor carpi radialis. The insertion of the ending tendon of the flexor carpi radialis was also variant, which was not only inserted into the base of the second metacarpal bone, but into the proximal surface of the scaphoid and the tubercle of trapezium. The excessive muscular bundle might be a residual muscular slip which connects between the distal part of the biceps brachii and the initial part of the flexor carpi radialis during the early embryonic development.