Apple #182: Brain Freeze

I was watching a movie the other night in which someone drank a slushie really fast and got a brain freeze (a.k.a., ice cream headache).


Brain freeze, coming at you


This led me to wonder, what makes that happen? And why do you feel it in your head and not, say, the roof of your mouth or the back of your throat or even in your stomach?

• When cold things touch the roof of your mouth, they activate a particular nerve, or bunch of nerves, in the sphenopalatine ganglion (sometimes known as the pterygopalatine ganglion).
• The spheno palatine nerves are responsible for sensation and glandular work in your palate (roof of mouth).

The sphenopalatine ganglion, shown as a yellow cluster, comes down sort of behind the roof of your mouth, at the back of your upper jaw. This is what reacts to cold foods.
(Image from Bartleby's searchable version of Gray's Anatomy, section on the Trigeminal Nerve)

• If the roof of your mouth doesn't have time to warm up and those nerves don't have time to relax, the nerves will tell the blood vessels in your brain to swell. The theory is that these nerves do this as a sort of misguided way of trying to keep your brain warm.
  
• When blood vessels in your brain swell, you experience that as pressure, or a headache.
• The headache will usually subside on its own within 10 to 20 seconds.
  
• But if you want to make the headache go away faster, you have to warm the roof of your mouth. You can do this by pressing your tongue to the roof and waiting a bit, or by drinking warm water.
• 7-11 owns the trademark to the word "brainfreeze."

P.S. The full moon you're seeing tonight is known as the Hay or Thunder or Buck moon. For more, see my entry on full moons.


Sources
Kidzworld, The Chilling Truth About Brain Freeze
Howstuffworks, What causes an ice cream headache?
The Straight Dope, What causes "ice cream headache?" June 28, 1991
Biology Online, definition of sphenopalatine ganglion and definitions of related terms
Joseph Hulihan, Ice cream headache, British Medical Journal, May 10, 1997