Hamstrings

Origin

Ischial tuberosity; short head of biceps femoris from the femur

Insertion

Fibular head (biceps femoris) and medial tibia (semitendinosus, semimembranosus)

Action

Flex the knee and extend the hip

Three muscles on the back of the thigh. Romanian deadlifts train their hip-extension role; leg curls train knee flexion.