If you don't know what chiro is doing ask about it - the good ones will be happy to explain.
C1/ C2 is the upper cervical or atlas/axis- that is a pretty simple and painless adjustment -{ talked about in the links below}

I hope the DC looked at your films/xrays before treatment..
just to be sure of no other issues that might be affected by adjustments.

Here is some nice info sites that I have found over the years -
Chiropractic care info- a good one can help with many symptoms:
http://www.upcspine.com/self.htm
http://www.uppercervical.org/subpag...b/about_faq.php
http://www.spineuniverse.com/index.html
http://www.coloradochiropractic.org/.../glossary.html