Rare Bilateral Variation of the Extensor Carpi Radialis Longus Muscle

Abstract

ObjectiveThe extensor carpi radialis longus (ECRL) is a superficial extensor muscle with a single muscle belly and tendon. In humans, the ECRL is found on the lateral forearm and serves to extend and abduct the hand at the wrist. While anatomical variations of the musculature of the extensor forearm are uncommon, it is essential for physicians working in this area of the body to be aware of possible variations.MethodsDissections of 68 upper limbs from 34 cadavers were performed and the musculature and neurovasculature of the lateral forearm was assessed.ResultsOne cadaver displayed an accessory muscle belly bilaterally with a long slender tendon arising from the ECRL muscle and inserting distally near the wrist. Both the accessory muscle on the right upper limb and left upper limb inserted on the abductor pollicis brevis muscle.ConclusionThis is a rare instance of a bilateral presentation of an accessory ECRL muscle, also known as the extensor carpi radialis accessorius (ECRA). Due to its infrequency, awareness of this accessory muscle and tendon may help physicians avoid improper muscle recognition when visualizing the area. As it is likely that the ECRA only weakly assists with the extension function of the ECRL, when present it may be used as an attractive autograft option for reconstructive surgery with minimal adverse effects.