This nerve wraps around the neck of the fibula and passes between the attachments of the fibularis longus before giving rise to the superficial peroneal nerve and deep peroneal nerve. Spinal nerves L4 through S1 comprise the common peroneal nerve. The common peroneal nerve itself derives from the terminating bifurcation of the sciatic nerve at the apex of the popliteal fossa the other terminal branch is the tibial nerve. The other branch is the superficial peroneal (fibular) nerve, which innervates the muscles of the lateral compartment of the leg. The deep peroneal nerve is one of two terminal branches at the bifurcation of the common peroneal (fibular) nerve. The deep peroneal nerve, also called the deep fibular nerve, innervates the tibialis anterior muscle. The medial arch is higher than the lateral arch and is formed by the following bones: calcaneus, talus, navicular, three cuneiforms, and the first three metatarsals. The tibialis anterior is such a powerful inverter that muscles of the lateral compartment must be engaged in eversion for the TA to dorsiflex the foot without inversion.ĭue to its insertion on the medial foot, the tibialis anterior also supports the medial longitudinal arch of the foot. The movement of inversion occurs at two synovial joints in the foot: the subtalar joint, between the talus and calcaneus, and the midtarsal joint, between the talus and navicular bone. Because the TA arises from the lateral tibia and the tendon inserts on the medial border of the foot, muscle contraction lifts structures of the medial arch (medial cuneiform, first metatarsal, navicular, talus) into adduction-supination or inversion. The tibialis anterior, along with the tibialis posterior, is also a primary inverter of the foot. Dorsiflexion is critical to gait because this movement clears the foot off the ground during the swing phase. The tibialis anterior (TA) is the strongest dorsiflexor of the foot. The main synovial bursa is between the tendon, the cuneometatarsal joint, and the medial cuneiform. The synovial tendon sheath of the tibialis anterior tendon extends from above the superior extensor retinaculum, inferiorly to the level of the talonavicular joint. In 25% of cases, however, the superficial and deep layers of the superior extensor retinaculum form a separate tunnel for the tibialis anterior tendon. In most cases, the tibialis anterior tendon passes beneath the extensor retinaculum, so the extensor retinaculum holds the TAT in place. The extensor retinaculum (ER), a transverse aponeurotic band comprised of superior and inferior components, covers the anterior ankle and foot. It is the most medial tendon of the ankle and foot. It travels across the anterior ankle and dorsum of the foot to insert vertically on the medial cuneiform and the base of the first metatarsal. The tibialis anterior tendon (TAT) begins at the distal one-third of the tibia. These include the lateral condyle of the tibia, the proximal two-thirds of the lateral surface of the tibial shaft, the anterior surface of the interosseous membrane between the tibia and fibula, the deep surface of the fascia cruris, and the intermuscular septum between it and the extensor digitorum longus. The tibialis anterior muscle, specifically its fleshy muscle belly, has a confluence of proximal attachments.
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