What causes Ice-cream headaches?

[D. Siwek]

In article <4g29f6$h14 at news.bu.edu>, cweaver at bu.edu (Charles Weaver) says:
>
>It is not! the phrenic nerve (this is the nerve that goes to the diapharam)
>unless you are getting hichoughs from eating icecream.  I always assumed it
>was a vascular thing.....the cold in the esophagus cools blood in the carotid

Not a bad thought.  I always get a real deep muscular pain sensation in the sub-occipital region when 
I pound down a cup of Ben and Jerrys.  I have always suspected that it had something to do with
"cold-cramping" of the pharynx and oropharynx with the pain refered to the sub-occipital region??
Perhaps out in left field  who knows?  Great idea for a science project!