A Rare Unilateral Variation of Extensor Digitorum Longus and Fibularis Tertius Muscles

Abstract

Purpose: Both the extensor digitorum longus (EDL) and fibularis tertius (FT) muscles exhibit a wide range of morphological variations. Methods: A 70-year-old male cadaver was subjected to routine anatomical dissection for research and teaching purposes. Results: The EDL had a markedly smaller fleshy belly, whereas the FT appeared hypertrophic. The EDL tendon displayed an atypical elongation and bifurcated into only three distinct slips, which inserted into the dorsal digital expansions of the second, third, and fourth toes. In contrast, the FT tendon was remarkably well-developed and divided into two slips. The lateral slip attached to the dorsal aspect of the base of the fifth metatarsal, while the medial slip extended distally to integrate into the dorsal digital expansion of the fifth toe. Conclusion: In injuries involving tendon incisions, clinicians should consider EDL variations to ensure proper tendon restoration. The FT muscle flap and tendon grafts are commonly used to correct ankle joint laxity and foot drop. Understanding variations in the EDL and FT is crucial for surgical planning.