Accessory slip of fibularis tertius to extensor digitorum longus - an unreported variant.

The fibularis tertius (FT) is one of three muscles which constitute the anterior compartment of the leg. The anatomical variants of this muscle usually pertain to its origins, number of final tendons or points, and shapes of insertions. In the particular case that we here report, it had an additional slip (AS) which originated from the same area as the main muscle belly and after descending along the extensor digitorum longus (EDL) it fused with one of its main tendons. The main muscle belly and its tendon, in its usual manner, reached the proximal dorsal surface of the fifth metatarsal bone. To the best of our knowledge, no similar case has been described before. This case reveals that human anatomy, though it may be thoroughly described, still contains surprises. Knowing about these variants is important from both the scientific and clinical points of view.