squeaker wrote on 14/04/2007 09:42 +0100:
Quoted message said:Just curious, but why does Tony focus on the energy needed to 'split
the skull' - I thought that internal bleeding of the brain due to
excessive forces between brain and skull was the usual cause of brain
damage, and that these can occur well before any skull fractures?
Not that I think that wearing a helmet is a particularly good idea -
pity that my wife does 🙁
Because that was the scenario posed by Coyoteboy that I was responding to:
Coytoteboy> I might not stop my face being ground off, but I will stop
my skull being split in all but the worst cases.
If you look back through my posts in response to Tom Crispin you will
find a reference to the mechanisms of brain injury. The type that
helmets are designed to protect against are the linear forces between
the brain and skull and produce focal superficial injuries. The type
they are not designed to protect against and which, because of their
extra mass and size on the head they exacerbate, are rotational injuries
where the brain tissue shears against itself and tears. Those injuries
are usually diffuse and serious. Bill Curnow has written a modern
summary if you can't get Holbourn's original Lancet paper.
http://preview.tinyurl.com/2y4bek
--
Tony
"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell