IntroductionThe peroneus tertius, also known as fibularis tertius, is a flat muscle located laterally to the extensor digitorum longus muscle, originating along the medial face of the fibula. Its fibers are sometimes mistaken for those of the extensor digitorum longus muscle. Actually, peroneus tertius is detached from the extensor digitorum longus muscle through a tendon that goes through the frondiform ligament of the extensor retinaculum and is inserted into the base of the fifth metatarsal bone.
1The muscle evaluated here acts during the swing phase of gait and is a powerful synergist for the extensor digitorum longus in dorsiflexion, abduction and lateral rotation of the feet.2,3 It is suggested, however, the insertion of the tendon in the fifth metatarsal could put more stress and, therefore, make it more easy for a avulsion fracture of the head of the fifth metatarsal to happen.
4The peroneus tertius is supplied by the anterior tibial nerve and anterior tibial artery. Its prevalence is 86% in African American, 90% in Jewish, and 93% in European as well as studies showing the muscle in constant development in bipedal animals. There may be a unique or double tendon and the insertion occurs in the fifth metatarsal, fourth metatarsal or in the interosseous space.
3,5The aim of the present study was to evaluate the prevalence and topography of the peroneus tertius muscle in cadaver parts to help clarify conflicting literature reports regarding this anterolateral structure of the leg.
Keywords► anatomy ► anatomic variation ► skeletal muscular fiber ► lower limb ► fibularis tertius
AbstractIntroduction The peroneus tertius muscle, also known as fibularis tertius, is classified as an anatomic variation and has been described as inconstant in a wide variety of contemporaneous studies and in the classical medical literature. Its fibers are sometimes mistaken for those of the extensor digitorum longus muscle. In fact, peroneus tertius is detached from the extensor digitorum longus muscle through a tendon inserted into the base of the fifth metatarsal bone, after passing through the frondiform ligament of the extensor retinaculum. Objectives The present study evaluated the prevalence, origin and insertion point of the peroneus tertius muscle in human cadavers. Methods and Results Thirty-two lower limbs, 18.75% of which came from female cadavers, were obtained from two different anatomy laboratories at two separate institutes. The cadaver parts were dissected and photographed. Overall, the muscle was present in 93.75% of the samples and in 100% of the samples from female cadavers. The fibers of the muscle originated in the proximal third of the fibula in 6.68% of cases, in the middle third in 46.66% and in the distal third in 46.66% of cases. Insertion of the tendon was at the base of the fifth metatarsal in 70% of cases and in the space between the fourth and the fifth metatarsal in 30%. Conclusion Therefore, the peroneus tertius muscle was present in the majority of the cadaver parts analyzed; however, the sites of ...