Inferior Peroneal Retinaculum

Fig. 17.22a,b. Peroneal tubercle and inferior peroneal retinaculum, a Schematic drawing of a lateral view of the hindfoot illustrates the peroneal tubercle curved arrow) as a bony prominence on the anterolateral aspect of the calcaneus. The tubercle separates the two peroneal tendons. The peroneus longus tendon (PL) runs inferiorly to the tubercle, while the peroneus brevis PB) is located superior to it. The inferior extensor retinaculum (asterisk) inserts into the lateral face of the calcaneus and the apex of the tubercle. It covers and stabilizes the peroneals during ankle movements, b Axial radiograph of the calcaneus shows the peroneal tubercle (curved arrow) as a bony protrusion from the anterolateral aspect of the calcaneus (Calc)... 

Fig. 16.9. Deep peroneal nerve. Anterior view of a gross dissection of the ankle shows the position of the deep peroneal nerve (arrows) relative to the tihialis anterior (ta), extensor hallucis longus (ehl) and extensor digitorum longus (edl) tendons as well as to the inferior extensor retinaculum (stars). LM, lateral malleolus. The insert at the left of the figure indicates the site of the anatomic specimen illustrated...

At the medial ankle, the tibial nerve, a continuation of the medial trunk of the sciatic nerve, passes deep to the flexor retinaculum in the space between the medial malleolus and the medial wall of the calcaneus (Fig. 16.10a). The retinaculum consists of a thin fascia and forms the roof of the tarsal tunnel (Fig. 16.10). In addition to the nerve, the tarsal tunnel encloses the tibialis posterior, flexor digitorum longus and flexor hallucis longus tendons, the posterior tibial artery and two veins (Fig. 16.10a,b). Posteroinferior to the medial malleolus, the tibial nerve divides into the medial and lateral plantar nerves and the calcaneal nerve, which is responsible for the sensitive supply of the heel (Fig. 16.11). The plantar nerves supply the intrinsic foot muscles, except for the extensor digitorum brevis, which is innervated by the deep peroneal nerve. The posterior tibial artery accompanies the nerve deep to the flexor retinaculum and, inferior to the medial malleolus, it divides into medial and lateral plantar arteries (Fig. 16.11). 

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