What makes your knucles crack

[Burki]

Terry Brooks wrote:
> 
> Can anyone tell me what makes your knuckles crack or where I might be able
> to find this info.
> Thank you

1. What has this to do with microbiology?

2. Our orthopedic surgeons *believe* in the following:
   Nitrogen is dissolved in the synovial liquid. When you extend a
joint    you lower the pressure inside, thus causing the N2 to go into
the    gaseous phase (cf. a bottle of soda). This happens explosively,
hence    the sound. Funny, isn't it?

-- 
Didi Burki, Berne/Switzerland
(to reply please replace amm by imm)