МРТ - в диагностике болезней суставов

and at the level of the ankle, both muscle and tendon are visible. The tendon of the flexor hallucis longus runs in a groove in the posterior aspect of the tibia then extends inferiorly and anteriorly below the medial tubercle of the talus and beneath the sustentaculum tali. The flexor digitorum longus tendon runs behind the medial malleolus between the flexor hallucis longus and the tibialis posterior. In the plantar aspect of the foot, the flexor digitorum longus crosses over the flexor hallucis longus. Both tendons are located deep to the abductor hallucis muscle and, the flexor digitorum brevis. The tibialis posterior tendon is the most anterior of the medial group. It passes behind the medial malleolus then courses anteriorly and divides into two separate tendons. The largest of these insert on the tuberosity of the navicular and extends to insert on the inferior aspect of the medial cuneiform. The smaller division passes laterally and inserts variably onto the middle three metatarsals and the intermediate cuneiform.

The two peroneus tendons make up the lateral group. Both tendons travel in a groove on the posterior aspect of the lateral malleolus and then extend anteriorly beneath

the malleolus (Figs. 9-1 and 9-2). The peroneus brevis is positioned anterior to the peroneus longus at the level of the lateral malleolus and superior to the peroneus longus beyond the malleolus. The peroneus brevis inserts on the lateral aspect of the base of the fifth metatarsal. The peroneus longus passes around the lateral malleolus and along the lateral aspect of the calcaneus inferior to the peroneal trochlea. It then changes ourse and extends medially in a groove on the inferior surface of the cuboid. It continues medially to insert on the base of the first metatarsal and the medial cuneiform.

The anterior group is composed of the tibialis anterior, the extensor hallucis longus, extensor digitorum longus, and peroneus tertius. The tibialis anterior is the most prominent of this group and is positioned medially. It inserts at the medial and inferior aspect of the medial cuneiform and at the base of the first metatarsal. The extensor hallucis longus runs lateral to the tibialis anterior and eventually inserts on the base of the first distal phalanx. The extensor digitorum longus and peroneus tertius are positioned most laterally and are difficult to separate

on cross-sectional images and anatomic specimens. The peroneus tertius muscle extends inferiorly to the level of the ankle and then becomes tendinous and attaches to the base and a portion of the shaft of the fifth metatarsal. In the region of the ankle, the extensor digitorum longus divides into four separate tendons which ultimately separate from each other and extend to the second through fifth digits. Figure 9-4 shows the orientation of these anterior tendons.

A number of muscles are present on the plantar aspect of the foot. The abductor hallucis is most medial and arises from the posterior medial surface of the calcaneus. As it extends anteriorly it covers the plantar arteries and nerves. The flexor digitorum brevis is located lateral to the abductor hallucis and also covers the lateral plantar artery and nerve. The abductor digit minimi is the most lateral of the plantar muscles. Deep to these three superficial muscles is the quadratus plantae.

Several neurovascular structures are visible in cross section and deserve attention. The posterior tibial artery

and tibial nerve roughly run superficial to the flexor hallucis longus and flexor digitorum longus with the artery positioned medial to the nerve (Fig. 9-1). Both course anteriorly at the level of the medial malleolus and extend to the plantar surface of the foot. Prior to entering the foot the nerve and artery divide into medial and lateral plantar branches. Both branches course between the abductor hallucis and the quadratus plantae. In the region of the ankle the medial branch is anterior and superior to the lateral branch.

The anterior tibial artery runs deep to the extensor hallucis longus in the ankle, then extends into the foot as the dorsalis pedis artery between the extensor hallucis longus and extensor digitorum longus (Fig. 9-4). The anterior tibial artery is accompanied by the deep peroneal nerve.

The peroneal artery is positioned posteriorly near the inferior tibiofibular joint. It is variably seen in crosssectional images and anatomic specimens.