Plantaris muscle

The plantaris muscle is a small, fusiform muscle located in the superficial posterior compartment of the leg. It originates from the lateral supracondylar line of the femur and the knee joint capsule, then descends distally as a long, slender tendon that courses between the gastrocnemius and soleus muscles. The tendon most commonly inserts onto the medial aspect of the calcaneal tuberosity, adjacent to or blending with the Achilles tendon, although considerable anatomical variation exists in both its origin and insertion.

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

Description: 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.