I don’t know about you, but I’ve seen so many patients in the past couple of years that have a lot of mechanical problems along the C2/3 segment.  During my assessment process, on the ispilateral side of these major C2/3 dysfunctions, I keep noticing significant hypomobilities of a postero-inferior glide at C1/2.  When looking at various assessment and treatment discussions of the C1/2 segment, what I usually see is a general look at the rotation of the segment without much regard to which side is moving (or not moving).  So, here is a video that talks of a quick way to check for this mobility.  Enjoy!