Biceps femoris muscle (long and short head)

The biceps femoris muscle has two heads, a lateral head and a short head. Both of these muscles insert onto the fibula and are innervated by the sciatic nerve. 

The short head attaches to the linea aspera of the femur and has the action of knee flexion since it only crosses the knee joint.

The long head is considered a "hamstring" since it attaches to the  ischial tuberosity, and since it crosses both the knee and the hip joints, it has the action of both knee flexion and hip extension.