What is the function of the quadriceps femoris?

• A. Knee extension
• B. Knee flexion
• C. Hip abduction
• D. Ankle dorsiflexion

Answer: (A)

The main function of the quadriceps femoris is to extend the knee. This group sits on the front of the thigh and contracts to pull on the patella via the quadriceps tendon; the force is transmitted through the patellar ligament to the tibial tuberosity, straightening the knee. This action is essential for standing up, walking, and climbing stairs. One part of the quadriceps, the rectus femoris, crosses the hip joint and can assist hip flexion, but the dominant role of the quadriceps is knee extension. The other movements listed are performed by different muscles: knee flexion mainly by the hamstrings, hip abduction by the gluteal muscles, and ankle dorsiflexion by the tibialis anterior and friends.