Absence of the peroneus tertius muscle: cadaveric study with clinical considerations

Peroneus tertius (PT) is a muscle of the anterior compartment of the leg. The PT muscle originates from the anterior surface of the fibula and the interosseous membrane and inserts into the medial side of the dorsal region of the fifth metatarsal bone. During routine dissection, we observed the absence of PT on the left lower limb of a cadaver. Usually, the PT is involved in dorsiflexion and eversion of the foot. In many cases, the absence of PT maybe asymptomatic and it may be incidentally detected during cadaveric dissections or autopsies. The existence of PT may help in the swing phase of bipedal walking. The PT may be used for tendon graft surgeries. The pull of the PT may be responsible for causing stress on the fifth metacarpal and account for all stress fractures in any individual. The absence of the PT may puzzle any transplant and foot surgeons performing graft operations. We as anatomists discuss the clinical implications of the absence of PT.