Origin: Lateral supracondylar ridge of femur above lateral head of gastrocnemius
Insertion: Tendo calcaneus (medial side, deep to gastrocnemius tendon)
Artery: Sural arteries
Nerve: Tibial nerve
Action: Plantar flexes foot and flexes knee
Antagonist: Tibialis anterior muscle
The Plantaris is placed between the Gastrocnemius and Soleus. It arises from the lower part of the lateral prolongation of the linea aspera, and from the oblique popliteal ligament of the knee-joint. It forms a small fusiform belly, from 7 to 10 cm. long, ending in a long slender tendon which crosses obliquely between the two muscles of the calf, and runs along the medial border of the tendo calcaneus, to be inserted with it into the posterior part of the calcaneus. This muscle is sometimes double, and at other times wanting. Occasionally, its tendon is lost in the laciniate ligament, or in the fascia of the leg.