Early in the development of chiropractic as well as in modern day chiropractic, a chiropractic adjustment could refer to moving or realigning almost any and every bone in the body. According to B.J. Palmer who developed chiropractic and the only person who could authoritatively define what an adjustment was, the only place an adjustment can occur is in the atlanto-axial-occipital region. The atlanto-axial-occipital region is also known as the C1-C2 vertebrae or the Atlas and the Axis. In addition to an adjustment only being able to given at C1 or C2, a subluxation must have been present. B.J. very strictly defined what a subluxation was in contrast to many chiropractors definition of a subluxation being any two bones being out of place.