plantaris /planter″is, plantä″ris/ [L, planta] , one of three superficial muscles at the back of the leg, between the soleus and the gastrocnemius. The plantaris is a small muscle that arises from the distal part of the linea aspera of the femur and from the oblique popliteal ligament of the knee joint. It has a small fusiform belly, ending in a long, slender tendon that inserts into the calcaneus. The plantaris is innervated by a branch of the tibial nerve containing fibers from the fourth and the fifth lumbar and the first sacral nerves. It plantar-flexes the foot and the leg. Compare gastrocnemius, soleus.
