Which muscle originates from the anterior and lateral shaft of the femur?

• A. Vastus Medialis
• B. Vastus Intermedius
• C. Vastus Lateralis
• D. Biceps Femoris Long Head

Answer: (B)

The key idea is recognizing where each muscle starts on the femur. The vastus intermedius is unique in originating from the anterior and lateral surface of the femoral shaft, lying deep between the vastus medialis and vastus lateralis. This placement on the front and outer side of the shaft distinguishes it from the other options. The vastus medialis starts medially near the line where the femur narrows, the vastus lateralis starts laterally near the greater trochanter and lateral lip of the linea aspera, and the biceps femoris long head begins at the ischial tuberosity, not on the femoral shaft. All three vastus muscles—and the biceps femoris—contribute to knee extension, but the specific origin on the anterior and lateral femoral shaft identifies the vastus intermedius.