Variant Extensor Muscle Of The Forearm arising From The Distal Part Of The Radius

A variant extensor muscle was encountered in the right forearm of a 62-year-old female cadaver. The variant muscle originated from the distal portion of the radius and coursed downward between the extensor pollicis longus and extensor pollicis brevis muscles and ended in a tendon. This tendon, was crossing obliquely the tendons of the extensor carpi radialis longus and extensor carpi radialis brevis muscles. It passed through the second tunnel for forearm extensor tendons under the extensor retinaculum together with the tendons of these two extensor carpi radialis muscles and finally inserted into the base of the second metacarpal bone with extensor carpi radialis longus muscle. Anatomical features of this variant muscle was detailed and compared with other variant extensor muscles of the forearm and the developmental viewpoint and clinical importance was stressed.