Tazman,
I think everyone who thinks that dead spot is under the spine mistakenly thinks the backbone runs along the very top of the back. I think the dead spot is actually OVER the spine.
Take a look at this link
http://home.mn.rr.com/deerfever/Anatomy.html
(I' m going to have to quit posting this guy' s link with out giving him some credit! lol)
Dac