Muscles: Actions, Origins & Insertions Practice Test

Muscles have specific attachment sites that determine their location and action. Vastus intermedius sits on the front of the thigh, originating from the anterior and lateral surface of the femur. That femoral-surface origin is distinctive for this muscle, and it explains why it’s the one described as starting from the femur itself.

In contrast, rectus femoris starts from the pelvis (the anterior inferior iliac spine), sartorius from the anterior superior iliac spine, and adductor longus from the pubic bone. So the only muscle among these that truly originates on the femur’s anterior/lateral surface is vastus intermedius, which also contributes to knee extension as part of the quadriceps.