Which muscle flexes the leg at the knee?

Which muscle flexes the leg at the knee?

• A. Quadriceps
• B. Gastrocnemius
• C. Abdominals
• D. Hamstrings

Answer: (D)

Knee flexion is produced by the hamstrings, a group of muscles at the back of the thigh. When they contract, they pull the lower leg backward, bending the knee and decreasing the angle between the thigh and lower leg. The quadriceps, located at the front of the thigh, extend the knee by straightening it. The abdominals are involved in trunk movements and don’t affect the knee joint. The gastrocnemius (a calf muscle) can assist knee flexion but its main role is plantarflexion of the ankle. So the primary muscle that flexes the leg at the knee is the hamstrings.

Knee flexion is produced by the hamstrings, a group of muscles at the back of the thigh. When they contract, they pull the lower leg backward, bending the knee and decreasing the angle between the thigh and lower leg. The quadriceps, located at the front of the thigh, extend the knee by straightening it. The abdominals are involved in trunk movements and don’t affect the knee joint. The gastrocnemius (a calf muscle) can assist knee flexion but its main role is plantarflexion of the ankle. So the primary muscle that flexes the leg at the knee is the hamstrings.