Hi Minimac,
It might be helpful for you to look up the anatomy involved. It might help explain certain things that are worrying you.

Also, between the skull and the brain lies the meninges and that acts as a cushion of sorts. The thickness of the skull varies somewhat from individual to individual as well. In my case it was noted that I had an extra thick cranium . At the time I found that an odd thing to be told but in retrospect it probably saved me. There are also differences in skull shape to be considered.