What action does the vastus lateralis perform?

What action does the vastus lateralis perform?

• A. Flexion of knee
• B. Abduction of thigh
• C. Knee extension
• D. Lateral rotation of thigh

Answer: (C)

Knee extension is the action of the vastus lateralis. This muscle is one of the four heads of the quadriceps femoris, situated on the front and lateral aspect of the thigh. It inserts into the patella via the quadriceps tendon and, through the patellar ligament, attaches to the tibial tuberosity. When it contracts, it straightens the knee by extending the knee joint, working together with the other quadriceps heads. It does not flex the knee, abduct the thigh, or laterally rotate the thigh—those movements involve other muscle groups around the hip or hamstrings. The vastus lateralis also helps stabilize the patella during extension.

Knee extension is the action of the vastus lateralis. This muscle is one of the four heads of the quadriceps femoris, situated on the front and lateral aspect of the thigh. It inserts into the patella via the quadriceps tendon and, through the patellar ligament, attaches to the tibial tuberosity. When it contracts, it straightens the knee by extending the knee joint, working together with the other quadriceps heads. It does not flex the knee, abduct the thigh, or laterally rotate the thigh—those movements involve other muscle groups around the hip or hamstrings. The vastus lateralis also helps stabilize the patella during extension.