Which muscle extends the knee and lies deep to the rectus femoris?

Which muscle extends the knee and lies deep to the rectus femoris?

• A. Vastus Intermedius
• B. Rectus Femoris
• C. Vastus Lateralis
• D. Vastus Medialis

Answer: (A)

The knee is extended mainly by the quadriceps group, and the one that lies deepest under the front muscle, the rectus femoris, is the vastus intermedius. Its fibers run between the other vastus muscles and it sits directly beneath rectus femoris in the anterior thigh. When it contracts, it helps straighten the knee as part of the quadriceps tendon assembly that attaches to the patella. Rectus femoris itself also extends the knee but sits superficially and crosses the hip, giving it a dual role. The other vasti are positioned at the sides and do not lie beneath rectus femoris.

The knee is extended mainly by the quadriceps group, and the one that lies deepest under the front muscle, the rectus femoris, is the vastus intermedius. Its fibers run between the other vastus muscles and it sits directly beneath rectus femoris in the anterior thigh. When it contracts, it helps straighten the knee as part of the quadriceps tendon assembly that attaches to the patella. Rectus femoris itself also extends the knee but sits superficially and crosses the hip, giving it a dual role. The other vasti are positioned at the sides and do not lie beneath rectus femoris.