Relations: Superficial to the soleus (closer to the skin) is the gastrocnemius muscle. The plantaris muscle and a portion of its tendon run between the two muscles. Deep to it (farther from the skin) is the transverse intermuscular septum, which separates the superficial posterior compartment of the leg from the deep posterior compartment. On the other side of the fascia are the tibialis posterior muscle, the flexor digitorum longus muscle, and the flexor hallucis longus muscle, along with the posterior tibial artery and posterior tibial vein and the tibial nerve. Since the anterior compartment of the leg is lateral to the tibia, the bulge of muscle medial to the tibia on the anterior side is actually the posterior compartment. The soleus is superficial midshaft of the tibia. Functions: The action of the calf muscles, including the soleus, is plantarflexion of the foot (that is, they increase the angle between the foot and the leg). They are powerful muscles and are vital in walking, running, and dancing. The soleus specifically plays an important role in standing; if not for its constant pull, the body would fall forward. Also, in upright posture, it is responsible for pumping venous blood back into the heart from the periphery, and is often called the peripheral heart or the sural (tricipital) pump. | 
