The popliteus muscle contributes to pain and stiffness behind the knee. The muscle is particularly affected by PCL injury and repair surgery.
The plantaris muscle is a very small muscle located behind the knee. It contributes to pain behind the knee and is occasionally involved in cramps in the calf.
The soleus muscle can cause and contribute to pain in the heel, ankle, and back of the knee. It can also cause pain in the low back on the same side of the affected leg. Dysfunction of the soleus muscle can also contribute to swelling in the foot and ankle. Occasionally a trigger point at the bottom and outside of the muscle can contribute to pain in the jaw and side of the head.