QUOTE(unfortunateson @ Jan 17 2005, 06:22 PM)
How do you not feel that?

QUOTE(unfortunateson @ Jan 17 2005, 07:24 PM)
a lack of nerves in the face?

there are actually a few very well documented cases where ppl injured their brain in a very serious way, but didn't realize it.
I'm not too much into physiological neuro sciences, but some parts of the brain can be damaged without real notice (there of course side effects, depending on the area).
as for the pain an accident like that usually inflicts, maybe the shock and surprise is able to mask it. plus, not knowing you should have pain sometimes helps to actually not having any (serious) pain.