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Calf Muscle – Types, Origin, Nerve Supply, Function

Calf Muscle refers to the posterior portion of the lower leg. The two largest muscles in this region include the gastrocnemius and the soleus. The gastrocnemius is the most superficial of the muscles and has two heads, medial and lateral. The two heads of the gastrocnemius converge and form a confluent muscle belly. The lateral head originates from the lateral surface of the lateral femoral condyle and the medial head from the posterior, non-articular aspect of the medial femoral condyle. The muscle belly of the gastrocnemius joins the soleus muscle distally to form the calcaneal tendon (i.e. the Achilles tendon), which inserts onto the posterior calcaneus.[rx][rx][rx][rx][rx]

The calf muscle plantarflexes the ankle joint and is innervated by the tibial nerve. The soleus is a large, flat muscle located deep to the gastrocnemius. The plantaris is a relatively small muscle with an appreciably long tendonous portion. The tendinous portion can easily be mistaken for a nerve. The plantaris muscle arises from the lateral supracondylar line of the femur and is completely absent in up to 10% of the population. The muscle descends medially, eventually forming into a tendon that runs down the leg, between the gastrocnemius and soleus. This tendon blends with the calcaneal tendon.

The Function of Calf Muscle

The calf muscles are responsible for plantarflexion the foot and ankle. The calf muscles are engaged in activities such as running and jumping.

Blood Supply of Calf Muscle

The blood supply of the calf muscles is derived from the

Popliteal artery, which divides into the anterior and posterior tibial arteries.
The fibular (or peroneal) artery originates from the posterior tibial artery.
The posterior tibial artery accompanies the tibial nerve and enters the plantar aspect of the foot through the tarsal tunnel.
The anterior tibial artery runs anteriorly between the tibia and fibula through a gap in the interosseous membrane. It extends down the entire length of the leg and into the foot becoming the dorsalis pedis artery.

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Nerves of Calf Muscle

Tibial nerve (S1, S2) innervates the majority of the muscles of the calf.
The tibial nerve passes through the popliteal fossa and gives off branches to the gastrocnemius, popliteus, soleus, and plantaris muscles.
There is also a cutaneous branch that will become the sural nerve.

Muscles

The lower leg consists of four compartments: anterior, lateral, superficial posterior, and deep posterior.

The anterior compartment includes the tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius, tibialis anterior and the deep peroneal nerve
The lateral compartment contains the peroneus longus and brevis and also the superficial peroneal nerve
The deep posterior compartment consists of the tibialis posterior, flexor hallucis longus, flexor digitorum longus, popliteus, and the tibialis nerve.
The tibialis posterior is the deepest of the four muscles and originates from the interosseous membrane between the tibia and fibula. It inverts and plantar flexes the foot and maintains the medial arch of the foot. The flexor digitorium longus (FDL) is located medially in the posterior leg and is responsible for flexing the lateral four toes. The flexor hallucis longus is located on the lateral side of the leg and flexes the great toe.
The popliteus muscle solely acts at the knee by internally rotating the tibia relative to the femur, thus its function is to “unlock” the knee joint during the initiation of flexion. The popliteus is located behind the knee joint and forms the base of the popliteal fossa
The superficial posterior compartment has the gastrocnemius, soleus, plantaris, and the sural nerve
The tibial nerve innervates all of the superficial and deep muscles of the calf.