The area of the back of the knee between the hamstring ~tendons~ is called the popliteal region. The politeal muscle is a thin, flat, triangular muscle that forms the base of this region. It arises from a strong, short ~tendon~ (about one inch long) from the |femur| (thigh bone) and the ~ligament~ behind the knee-joint and extends to the shaft of the |tibia|. This muscle assists in rotating the |tibia| and is used when bending the knee.