VARIATIONS IN THE MUSCLES OF THE EXTENSOR COMPARTMENT OF THE FOREARM AND HAND AND ITS CLINICAL SIGNIFICANCE

Background: The extensor musculature of the forearm and hand shows diverse variations. These can lead to various clinical conditions. Case Report: During routine cadaveric dissection, variations were observed in the muscles of extensor compartment of the forearm. Their anatomical relations were documented and the embryological basis and clinical importance was stressed upon. During routine cadaveric dissection in a formalin fixed 58 year old male cadaver, variations in the posterior compartment of the left forearm were noted, measured and appropriately photographed. Observations: In the posterior compartment of the left forearm an accessory muscle was found originating from the posterior surface of ulna, just distal to the origin of extensor indicis. It traversed along with the tendons of extensor digitorum and extensor indicis in a common compartment underneath the extensor retinaculum and inserted onto the dorsal surface of the base of the proximal phalanx lateral to the tendon of extensor digitorum for the middle finger. Also, the extensor digitorum muscle divided only into three tendons instead of four- one each for the index, middle and ring finger. The three tendons inserted normally via the dorsal digital expansion but, the tendon for the ring finger gave an additional slip on the ulnar aspect, which inserted separately onto the base of the proximal phalanx of the ring finger. Conclusion: Muscles in the extensor compartment of forearm may show diverse variations which have clinical relevance. Accessory muscles may be confused with soft tissue conditions like a ganglion. Supernumary tendons can be utilised for tendon transfers and muscle grafts. These variations must be brought to the knowledge of the surgeons performing hand surgeries.