International Journal of Advances In Case Reports

A CASE REPORT - ABSENCE OF PERONEUS TERTIUS MUSCLE

Tanya Vijan*, Sharadkumar Pralhad Sawant, Rakhi M. More, Shaguphta T. Shaikh, Shaheen Rizvi, Uma R

tanyasvijan@gmail.com

Absence of Peroneus tertius, Asymptomatic,Tendon graft surgeries.

Peroneus tertius (fibularis tertius) is a uniquely human muscle. It often appears to be part of extensor digitorum longus, and might be described as its „fifth tendon‟. The muscle fibres operating on this tendon arise from the distal third or more of the medial surface of the fibula, the adjoining anterior surface of the interosseous membrane, and the anterior crural intermuscular septum. The tendon passes behind the superior extensor retinaculum and within the loop of the inferior extensor retinaculum it shares with extensor digitorum longus. Peroneus tertius lies lateral to extensor digitorum longus. It is inserted into the medial part of the dorsal surface of the base of he fifth metatarsal bone, and a thin expansion usually extends forwards along the medial border of the shaft of the bone. During routine dissection, we observed that Peroneus tertius was absent on the left lower limb of a 70 years old donated embalmed male cadaver in the Department of Anatomy, K.J.Somaiya Medical College,Sion,Mumbai,India. Usually, the Peroneus tertius is involved in dorsiflexion and eversion of the foot. In many cases, the absence of Peroneus tertius may be asymptomatic and it may be incidentally detected during cadaveric dissections or autopsies. The existence of Peroneus tertius may help in the swing phase of bipedal walking. The Peroneus tertius may be used for tendon graft surgeries. The pull of the Peroneus tertius may be responsible for causing stress on the fifth metacarpal and account for all stress fractures in any individual. The absence of the Peroneus tertius may puzzle any transplant and foot surgeons performing graft operations. We as anatomists discuss the clinical implications of the absence of Peroneus tertius.