Which action is performed by the Quadriceps muscle group?

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

Answer: (C)

Knee extension is performed by the quadriceps muscle group. These four muscles lie on the front of the thigh and cross the knee joint. They pull on the patella via the quadriceps tendon and then insert on the tibial tuberosity through the patellar ligament. When they contract, they straighten the knee, which is essential for standing up, climbing stairs, and pushing off during walking. The rectus femoris, while it can assist hip flexion because it crosses the hip, still mainly functions to extend the knee. The other movements listed are produced by different muscles: knee flexion by the hamstrings, ankle dorsiflexion by the tibialis anterior, and hip abduction by the gluteal muscles.