Flexor Hallucis Longus

Tibial Nerve, Sciatic Nerve, Ventral Division Sacral Plexus, L5, S1, S2. 

From the inferior two-thirds of the posterior surface of body of the fibula and the interosseus membrane. 

Insert the electrode obliquely five fmgerbreadths above the insertion of the Achilles tendon (AT) and anterior to the medial border of this tendon towards the tibia. 

Patient to flex the big toe, keeping the ankle and the small toes relaxed. 

If the electrode is inserted too deeply it will be in the tibialis posterior if inserted too anteriorly it will be in the flexor digitorum longus if inserted too proximal it will be in the lower fibers of the soleus. 

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Tibialis anterior and extensor digitorum longus Gastrocnemius, soleus, and flexor hallucis longus Iliopsoas "... 

Type 1 tendons are long and cross at least one joint before they attach. They may course over and around bony structures and at these locations are invariably covered by a synovial sheath comprised of visceral and parietal layers. The visceral layer is intimately attached to the tendon surface and moves with the tendon. The parietal layer is a lax covering that blends with the visceral layer at the periphery of the tendon sheath to become the mesotendon, which contains the tendon vessels. The synovial sheath has the function of decreasing the friction between the tendon and the adjacent structures allowing smooth excursion of the tendon. A small amount of fluid may be present within the tendon sheath. Certain tendon sheaths may communicate with adjacent joints, in which case excess joint fluid may result in distension of the tendon sheath. A good example of this is the flexor hallucis longus tendon, which often communicates with the tibiotalar joint... 

Gluteus medius, minimus, and tensor fascia lata Vastus lateralis and vastus intermedius Vastus medialis and vastus lateralis Tibialis anterior and extensor digitorum longus Gastrocnemius, soleus, and flexor hallucis longus Iliopsoas "... 

Fig. I5.I0a,b. Accessory soleus muscle (type 1). a Longitudinal extended field-of-view 12-5 MHz US image over the Achilles tendon (arrowheads) reveals the aberrant soleus muscle (arrows) inserting into the deep surface of the tendon. The muscle ends in proximity to the calcaneus and occupies a large part of Kager s space, b Axial CT scan confirms the presence of an accessory muscle (arrows) located between the distal Achilles tendon (At) and the flexor hallucis longus muscle (FHL)...

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). 

Fig. 16.33. Normal posterior recess of the ankle joint. Longitudinal 12-5 MHz US image over the Achilles tendon (A) reveals the concave appearance of the posterior recess (arrows) of the ankle joint that lies between the posterior malleolus of the tibia (T) and the posterior talus (Ta). Note the deep location of this recess relative to the soleus (so) and the flexor hallucis longus (fhl) muscles. It contains a physiologic small amount of fluid (asterisk). Star, posterior fat pad. The photograph at the upper left of the figure indicates probe positioning...

Clinical features include limited plantar flexion of the foot compared with that of the nonaffected side and posterior ankle pain exacerbated hy plantar and dorsal flexion of the foot, anterior to and not involving the Achilles tendon. Bony abnormalities in this area, and especially at the level of the posterior talus, may predispose to this syndrome. From the anatomic point of view, the posterior aspect of the talus has two tubercles, the medial and the lateral tubercle, between which the osteofibrous tunnel of the flexor hallucis longus tendon lies. In the ossification process of the... 

Fig. 16.87 a,b. Synovitis of the ankle joint posterior recess, a Sagittal 12-5 MHz US image over the posterior ankle demonstrates hypoechoic fluid (arrows) within the posterior recess of the ankle joint between the posterior malleolus (PM) and the talus, in close relation to the flexor hallucis longus tendon (fhl). b Lateral radiograph shows increased density (arrows) at the level of the posterior recess, reflecting synovitis... 

Sammarco GJ, Cooper PS (1998) Flexor hallucis longus tendon injury in dancers and nondancers. Foot Ankle Int 19356-362 Sandelin J, Kivilehto O, Santavirta S (1985) Outcome of sports injuries treated in a causalty department. Br J Sport Med 19 103-106... 

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