1) The Gastrocnemius is the calf muscle that is visible from the outside of the body. It attaches to the heel with the Achilles tendon and originates behind the knee on the femur, crossing two joints.
2) The Soleus is not visible when looking at the body from the outside as it lies underneath the Gastrocnemius on the rear of the lower leg.
The role of calf muscles
The calf muscles play an important pumping role in venous circulation. When your calf muscles contract, they compress the veins within the muscles and force the blood to flow upward and toward the heart. When your calf muscles relax, the veins in the muscles refill with blood from surrounding veins. The calf muscle pump is often called the peripheral heart.
Left: Gastrocnemius stretch
Right: Soleus stretch
Lot of people are having a difficult time to stretch their soleus. The Soleus stretch should be smaller and deeper than the Gastrocnemius stretch. Also the position of shoulders are different. To stretch the soleus, shoulder and hips are in line.
Keep pressing the heel instead of toes.
Strong calf muscles will stabilize your feet and you will perform better squats and lunges.