Which nerve innervates the vastus intermedius?

Which nerve innervates the vastus intermedius?

• A. Obturator nerve
• B. Femoral nerve
• C. Tibial nerve
• D. Sciatic nerve

Answer: (B)

The key idea is which nerve supplies the muscles that extend the knee in the anterior thigh. The vastus intermedius is one of the quadriceps femoris muscles, lying deep between the vastus medialis and vastus lateralis, and it helps straighten the knee. All quadriceps muscles receive motor input from the femoral nerve, which originates from L2–L4 and travels into the anterior thigh to reach these muscles. That makes the femoral nerve the correct innervation for the vastus intermedius. The obturator nerve supplies the medial thigh adductors and does not reach the quadriceps. The tibial and sciatic nerves primarily serve the posterior compartment and muscles of the leg and foot, not the quadriceps.

The key idea is which nerve supplies the muscles that extend the knee in the anterior thigh. The vastus intermedius is one of the quadriceps femoris muscles, lying deep between the vastus medialis and vastus lateralis, and it helps straighten the knee. All quadriceps muscles receive motor input from the femoral nerve, which originates from L2–L4 and travels into the anterior thigh to reach these muscles. That makes the femoral nerve the correct innervation for the vastus intermedius.

The obturator nerve supplies the medial thigh adductors and does not reach the quadriceps. The tibial and sciatic nerves primarily serve the posterior compartment and muscles of the leg and foot, not the quadriceps.