I was vacuuming the second row carpet in my vehicle. I was leaning into my vehicle and pulled the second row seat release to move the seat back. The back of the seat flipped forward hitting me in the right side of my head so hard it resulted in a pinched nerve at C5-C6. It was a substantial blow. I had to stop what I was doing and sit down. I would be very concerned at that amount of force hitting a child. Has Toyota measured the force and done a risk analysis to the vehicle occupant?