Which muscle group is primarily responsible for knee flexion?

Which muscle group is primarily responsible for knee flexion?

• A. Quadriceps femoris
• B. Sartorius
• C. Gastrocnemius
• D. Hamstrings

Answer: (D)

Knee flexion means bending the knee, which is mainly produced by the hamstrings. This group runs along the back of the thigh and crosses the knee joint, attaching to the tibia and fibula. When the hamstrings contract, they pull the lower leg backward, decreasing the angle at the knee and bending it. The quadriceps femoris on the front of the thigh is the primary knee extensor, opposing knee flexion. The gastrocnemius crosses the knee as well as the ankle and can assist with knee bending, but its main role is plantarflexion of the foot, so its contribution to knee flexion is secondary. The sartorius can aid knee flexion too, but it’s not the primary mover.

Knee flexion means bending the knee, which is mainly produced by the hamstrings. This group runs along the back of the thigh and crosses the knee joint, attaching to the tibia and fibula. When the hamstrings contract, they pull the lower leg backward, decreasing the angle at the knee and bending it.

The quadriceps femoris on the front of the thigh is the primary knee extensor, opposing knee flexion. The gastrocnemius crosses the knee as well as the ankle and can assist with knee bending, but its main role is plantarflexion of the foot, so its contribution to knee flexion is secondary. The sartorius can aid knee flexion too, but it’s not the primary mover.