A cadaveric report of unilateral fibularis tertius in absentia: a clinical perspective

Introduction Fibularis tertius (FT), formerly known as peroneus tertius is a unique muscle in human being, often considered as a fifth tendon of extensor digitorum longus. The muscle originates from the distal one third or medial fibular surface, anterior surface of the interosseous membrane and anterior crural intermuscular septum. Thereafter, the tendon runs beneath the superior extensor retinaculum, inferior extensor retinaculum and gets inserted into dorsal surface of fifth metatarsal. Fibularis tertius is supplied by deep peroneal nerve and assists in dorsiflexion of foot in swing phase and evertion of foot [1]. Vertullo et al. considered its insertion site as an important factor in case of Jones fracture [2]. A study conducted by Joshi et al. concluded that muscle might remain rudimentary or even absent in 4.4-10% cases in humans [3]. Another similar study carried out on Caucasian population showed its absence in 5-17% of cases studied [4].