If you were to remove the gastrocnemius muscle you would expose the soleus muscle. The gastrocnemius muscle and the soleus muscle are the two major muscles that are located on the back part of the lower leg in humans. The soleus muscle is situated underneath the gastrocnemius muscle. The gastrocnemius muscle provides the propelling force in running and jumping by pulling the heel up and extending the foot downward. The soleus muscle is also involved in standing and walking.