Muscles that Move the Ankle and Foot
Many muscles do the work of moving the ankle and foot. Some of the muscles that move the foot start higher up in the leg, and smaller muscles work right in the foot itself. The leg is divided into compartments: the anterior, lateral, and posterior compartments. The muscles in these compartments help move the ankle and the foot:
Anterior compartment: This compartment lies in front of the tibia and fibula and is surrounded by fascia. The anterior muscles dorsiflex the foot at the ankle and extend the toes.
Lateral compartment: The muscles here sit on the outer side of the leg and help evert the foot.
Posterior compartment: This larger compartment is on the back of the leg. It has two layers of muscles, which are divided by a section of fascia called the transverse intermuscular septum. The posterior muscles plantarflex the ankle and flex the toes.
The tendons of the anterior dorsiflexors are held in place at the ankle by the thickened piece of fascia called the superior and inferior extensor retinaculum. These muscles are innervated by the deep fibular (peroneal) nerve:
Tibialis anterior: This muscle originates on the lateral surface of the tibia and inserts on the medial cuneiform and base of the first metatarsal. It dorsiflexes the ankle and inverts the foot.
Extensor digitorum longus and extensor hallucis longus: These muscles originate on the anterior surfaces of the shaft of the fibula and interosseous membrane. The extensor digitorum longus tendons insert on the middle and distal phalanges of the second, third, fourth, and fifth toes. The extensor hallucis longus inserts on the distal phalanx of the big toe. They dorsiflex the ankle and extend the toes.
Fibularis (peroneus) tertius: This muscle originates on the anterior surface of the shaft of the fibula and inserts on the base of the fifth metatarsal bone. It dorsiflexes the ankle and everts the foot.
The lateral compartment contains two muscles: the fibularis (peroneus) longus and fibularis (peroneus) brevis. They originate on the lateral surface of the fibula. The fibularis longus inserts on the base of the first metatarsal and medial cuneiform, and the fibularis brevis inserts on the base of the fifth metatarsal. They’re innervated by the superficial fibular (peroneal) nerve and help to plantarflex and evert the foot.
The posterior plantarflexors are innervated by the tibial nerve. They are divided into superficial and deep layers. The tendons are held in place at the ankle by a thickened piece of fascia called the flexor retinaculum.
The following superficial muscles, which plantarflex the ankle, have different origins, but they all merge into the calcaneal tendon, which inserts into the back of the calcaneus:
Gastrocnemius: This muscle has two heads. The lateral head originates from the lateral condyle of the femur, and the medial head originates from the medial condyle.
Plantaris: This muscle originates at the lateral supercondylar line of the femur.
Soleus: This muscle originates on the shafts of the tibia and fibula.
Following are the deep muscles of the posterior compartment of the leg that plantarflex the ankle and flex the toes:
Flexor hallucis longus: This muscle originates on the distal two-thirds of the posterior surface of the shaft of the fibula and inserts into the base of the distal phalanx of the big toe. It plantarflexes the ankle and flexes the big toe.
Flexor digitorum longus: This muscle originates on the posterior surface of the tibia, and the tendons insert into the bases of the distal phalanges of the lateral four toes. It plantarflexes the ankle and flexes the lateral four toes.
Tibialis posterior: This muscle originates on the posterior surfaces of the shafts of the tibia and fibula, and the interosseus membrane and inserts on the tuberosity of the navicular bone. It plantarflexes the ankle and inverts the foot.