An Anatomical Variation of Extensor Indicis Muscle: A Case Report

The extensor indicis is a narrow, elongated skeletal muscle in the deep layer of the dorsal forearm that originates from the one third of the distal posterior surface of the shaft of ulna below the origin of the extensor pollicis longos and interosseous membrane. It runs through the fourth tendon compartment with the extensor digitorum under the extensor retinaculum. The extensor indicis joins to the ulnar side of the extensor digitorum communis opposite the head of the second metacarpal bone. This muscle allows independent extension of the index finger. In a cadaver dissection we observed two extensor indicis muscles with the same origin but two separate belleis and tendons. One of them was attached to the dorsum of the index finger and another one to the tendon of extensor digitorum muscle and to the index finger via extensor expansion.