Soleus muscle

Origin: Fibula, medial border of tibia (soleal line)

Insertion: Tendo calcaneus

Artery: Sural arteries

Nerve: Tibial nerve, specifically, nerve roots L5–S2

Action: Plantarflexion

Antagonist: Tibialis anterior muscle

Description:
The Soleus is a broad flat muscle situated immediately in front of the Gastrocnemius. Itarises by tendinous fibers from the back of the head of the fibula, and from the upper third of the posterior surface of the body of the bone; from the popliteal line, and the middle third of the medial border of the tibia; some fibers also arise from a tendinous arch placed between the tibial and fibular origins of the muscle, in front of which the popliteal vessels and tibial nerve run. The fibers end in an aponeurosis which covers the posterior surface of the muscle, and, gradually becoming thicker and narrower, joins with the tendon of the Gastrocnemius, and forms with it the tendo calcaneus.
Variations.—Accessory head to its lower and inner part usually ending in the tendocalcaneus, or the calcaneus, or the laciniate ligament.