The term "calf muscles" refers to a group of muscles located in the lower leg, specifically behind and below the knee. These muscles are responsible for various movements such as standing on tiptoe, flexing the foot, and assisting with walking or running. The two main calf muscles are the gastrocnemius (which is the larger of the two) and the soleus. Together they form the calf and play an important role in maintaining balance and stability while standing and walking.