The biceps femoris is the largest muscle of the hamstring group and has two heads.
At the upper end the long head is attached to the tuberosity of the ischium bone of the pelvic girdle. The short head is attached to the middle and central area of the femur bone of the thigh.
At the lower end the biceps femoris is attached to the lateral condyle of the tibia and the head of the fibula bones of the shin. The tendon of insertion (which attaches to the bone) forms the lateral hamstring.
Knee joint flexion.