Anatomic variations of the hand extensor muscle tendons

Abstract

Variations of muscles on the dorsal aspect of the forearm are seen very common. These variations can be symptomatic but generally they are diagnosed incidentally. On the posterior compartment of forearm, extensor carpi radialis brevis related to abduction of the wrist and extensor digitorum related to extension of the wrist and fingers. This case report showed rare variations of extensor carpi radialis brevis and extensor digitorum muscles. During routine dissections of the extensor compartment of the forearm for anatomy education, it was observed that extensor carpi radialis brevis muscle had an accessory head which attached to dorsum and proximal phalanx of the index finger. Besides, it was found that extensor digitorum muscle divided into three tendons distally. When we followed these tendons, it was observed that tendon of index finger was absent and other three tendons went to middle, ring and little fingers. Accessory muscles located on the extensor compartment of the forearm are seen common. They can be reason of the symptoms of the nerve entrapment. Besides, these unusual muscles may confuse radiologists, surgeons and anatomists. In order to prevent diagnostic errors and avoid surgical complications, these anatomical variations should be well-known.