In truth however; in reply to your opening inquiry; up until the age of ten i lived on a farm, once at the age of approx eight i was thrown from a horse and did indeed strike my head on a sizable rock lying on the track-way that served as the road down to the milking shed.
Approx a year later i was standing on the plowing tractor my brother was driving in the field. I was standing leaning against the large back driving wheel tyre mudguard.
Something caused me to be thrown forward, for many decades I always never really believed my head ended up under the front tractor wheel and the back tractor wheel on my foot...
In truth i often thought if this truly happened if this truly happened how i could remain undamaged; approx two decades later at a family reunion my older brother related that story as true. I know I had never revealed that story to anyone as I felt i would never have been believed.
My only explanation now simply remains that the field had been well plowed and this prevented most likely injuries...
Still i remain amazed such an occurrence could not leave any lasting issues; or maybe it did :)
/hugz ;)