Question: What happens when we have a brain freeze? when we eat something cold and then our head hurts.

Iroise Dumontheil answered on 18 Nov 2016:

I’ve actually never looked this up in before – in fact I haven’t never experienced it myself, maybe I don’t eat ice cream fast enough. But it seems this article explains what happens:
https://www.sciencedaily.com/releases/2013/05/130522095335.htm
Apparently it’s officially called sphenopalatine ganglioneuralgia, and when you eat/drink something cold it dilates or contracts arteries at the back of the throat and triggers receptors in the meninges, which cover the brain, and this signal from the receptors is interpreted as pain. It’s like a very fast and temporary headache and a signal to stop doing whatever you’re doing!