Leg and ankle

• The leg is divided into three compartments: Anterior, Lateral, and Posterior.
• The Anterior Fascial Compartment of the Leg contains muscles: tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus.
• The blood supply of the Anterior Fascial Compartment of the Leg is provided by the Anterior Tibial Artery.
• Muscular branches of the nerve supply the soleus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles.
• The nerve, with the artery, passes behind the medial malleolus and under the flexor retinaculum, dividing into the medial and lateral plantar nerves.
• The medial and lateral plantar nerves are branches of the nerve.
• An articular branch of the nerve supplies the ankle joint.
• Cutaneous branches of the nerve supply the medial calcaneal nerve.
• The nerve supply of the Anterior Fascial Compartment of the Leg is provided by the Deep Peroneal Nerve.
• The action of the muscles in the Anterior Fascial Compartment of the Leg is to extend the foot at the ankle joint, invert the foot, and support the medial longitudinal and arch of the foot.
• The Extensor Digitorum Longus muscle, located in the Anterior Fascial Compartment of the Leg, extends the toes and extends the foot at the ankle joint.
• The Peroneus Tertius muscle, located in the Anterior Fascial Compartment of the Leg, everts the foot.
• The Extensor Hallucis Longus muscle, located in the Anterior Fascial Compartment of the Leg, extends the big toe, extends the foot at the ankle joint, and inverts the foot.
• The Extensor Digitorum Brevis muscle, located in the Anterior Fascial Compartment of the Leg, is extended by four tendons into the big toe and second, third, and fourth toes.
• The Anterior Tibial Artery is the smaller terminal branch of the popliteal artery, arises at the lower border of the popliteus muscle, and descends on the anterior surface of the interosseous membrane, accompanied by the deep peroneal nerve.
• The Deep Peroneal (Fibular) Nerve, which arises at the level of the neck of the fibula within the peroneus (fibular) longus muscle, descends through the anterior compartment of the leg accompanied by the anterior tibial artery and supplies muscles of the anterior compartment in addition to the extensor digitorum brevis.
• The Lateral Fascial Compartment of the Leg contains muscles: Peroneus (fibularis) longus and peroneus (fibularis) brevis.
• The blood supply of the Lateral Fascial Compartment of the Leg is provided by the Peroneal (Fibular) Artery.
• The nerve supply of the Lateral Fascial Compartment of the Leg is provided by the Superficial Peroneal (Fibular) Nerve.
• The action of the muscles in the Lateral Fascial Compartment of the Leg is to plantar flex the foot at the ankle joint, ever the foot, and support the lateral longitudinal and transverse arches of the foot.
• The Peroneus Longus muscle, located in the Lateral Fascial Compartment of the Leg, plantar flexes the foot at the ankle joint, everts the foot, and supports the lateral longitudinal and transverse arches of the foot.
• The posterior tibial artery runs down on the tibialis posterior and passes behind the medial malleolus deep to the flexor retinaculum, terminating by dividing into medial and lateral plantar arteries.
• The action of the popliteus muscle is to flex the leg at the knee joint, unlock the knee joint by lateral rotation of the femur on the tibia, and slacken ligaments of the joint.
• The superficial group of muscles in the posterior fascial compartment of the leg includes the gastrocnemius, plantaris, and soleus muscles.
• The action of the tibialis posterior muscle is to plantar flex the foot at the ankle joint, invert the foot, and support the medial longitudinal arch of the foot.
• The nerve supply to the posterior fascial compartment of the leg is provided by the tibial nerve.
• The tibial nerve is the larger terminal branch of the sciatic nerve and accompanies the posterior tibial artery.
• The peroneal artery, a branch of the posterior tibial artery, gives off muscular branches and a nutrient artery to the fibula.
• The action of the plantaris muscle is to plantar flex the foot at the ankle joint and flex the knee joint.
• The medial and lateral plantar arteries, also branches of the posterior tibial artery, supply the foot.
• The posterior tibial artery is one of the terminal branches of the popliteal artery and begins at the level of the lower border of the popliteus muscle.
• The action of the soleus muscle is to plantar flex the foot at the ankle joint and support the medial and lateral longitudinal arches of the foot.
• The nutrient artery to the tibia, also a branch of the peroneal artery, supplies the tibia and fibula.
• The action of the flexor digitorum longus muscle is to flex the distal phalanges of the lateral four toes and plantar flex the foot at the ankle joint.
• The blood supply to the posterior fascial compartment of the leg is provided by the posterior tibial artery.
• The anastomotic branches around the ankle joint are branches of the posterior tibial artery.
• The action of the flexor hallucis longus muscle is to flex the distal phalanx of the big toe and plantar flex the foot at the ankle joint.
• The action of the gastrocnemius muscle is to plantar flex the foot at the ankle joint and flex the knee joint.
• The muscular branches of the peroneal artery supply the tibia and fibula.
• The deep group of muscles in the posterior fascial compartment of the leg includes the popliteus, flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles.