What action does the vastus medius perform?

What action does the vastus medius perform?

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

Answer: (B)

Knee extension. The vastus medius is one of the four quadriceps muscles that straighten the knee by pulling on the patella through the quadriceps tendon and transmitting force to the tibial tuberosity via the patellar ligament. It also helps stabilize the patella medially during extension. It does not flex the knee, cross the hip to flex it, or move the ankle; those actions are performed by other muscles (hamstrings for knee flexion, iliopsoas for hip flexion, tibialis anterior for ankle dorsiflexion).

Knee extension. The vastus medius is one of the four quadriceps muscles that straighten the knee by pulling on the patella through the quadriceps tendon and transmitting force to the tibial tuberosity via the patellar ligament. It also helps stabilize the patella medially during extension. It does not flex the knee, cross the hip to flex it, or move the ankle; those actions are performed by other muscles (hamstrings for knee flexion, iliopsoas for hip flexion, tibialis anterior for ankle dorsiflexion).