An Extensor Digitorum Muscle for Index Finger Originated from the Extensor Carpi Radialis Brevis

Abstract

The anomalous variations in the extensor carpi radialis brevis (ECRB) and extensor digitorum (ED) muscles of the forearm have been previously reported in the literature. The present article reported an anomalous variation of the ECRB and ED muscles in the forearm. We found an accessory muscle originated from the medial side of the ECRB muscle and inserted into the base of second metacarpal bone. And the ED muscle divides into three distinct tendons without the tendon of index finger. This case is a first report of the variations of ECRB and ED muscle in Korean cadaver. Knowledge of this variation is important to avoid surgical complications and to prevent diagnostic problems. Its embryological and clinical significances were discussed.

Extensor digitorum muscle tendon to the index finger from the extensor carpi radialis brevis: a cadaveric case report

“…An aberrant ED-index was described by Kim et al [13]. Similarly to the present study, it originated from the ECRB muscle and inserted into the index finger.…”

“…The ED arose from the lateral epicondyle of humerus and was divided into three musculotendinous bellies. There was no index finger tendon of the ED muscle [13].…”

“…The ED arises from the lateral epicondyle of humerus and divides into four tendons, inserting into the lateral and dorsal surface of the middle and distal phalanges of the 2 nd -5 th finger [13]. Most studies describe the ED to give off one tendon directly to the extensor expansion of hand of each one of the above-mentioned four digits [3].…”

“…Most studies describe the ED to give off one tendon directly to the extensor expansion of hand of each one of the above-mentioned four digits [3]. The extensor carpi radialis brevis (ECRB) also arises from the lateral epicondyle of humerus and inserts as a flat tendon into the styloid process of metacarpal III [13,24]. The ED and the ECRB muscles are both innervated by the radial nerve.…”