Tipping
This is a subluxation in which the one transverse process is, or appears to be, superior or inferior to the other. It occurs frequently to the Atlas in combination with lateral subluxation. In fact, the shape of the occipito-atlantal articulations is such that, if the remaining Cervicals maintain their proper relation to each other, the Atlas cannot be laterally displaced without a certain amount of tipping. It will be relatively superior on the prominent side and the head will be tipped toward that side; that is toward the side of the lateral displacement. Thus, on account of the wedge-shaped lateral masses, if the whole Atlas be to the right of its normal position the right side will be superior and the head tipped toward the right. This is only true when the vertebrae below maintain a normal interrelation.
Approximation
This is a name applied to that condition in which, on account of changes in the intervertebral disks due to subluxation interfering with metabolic processes, the bodies or spinous processes of vertebrae are crowded too closely together.
Occasionally a spine is found in which, on palpation, the spinous processes are found to be crowded together in groups, sometimes of two or three, sometimes of five or six; no two interspaces appear equal, a very wide one being succeeded by one or two which are almost inappreciable; the variation in width of the interspaces does not correspond to the known normal variation in those regions where the changing obliquity of spinous processes should modify the relative width of successive spaces. We expect, for instance, to find a wider space between third and fourth Dorsals than between second and third; if we do not find this difference it is doubtless due to cartilage change and the vertebrae are approximated.
In case of general thinning of intervertebral substance unequally divided between different sections of the spine the record will show that almost every vertebra is listed either S or I, and if a system of underscoring is used that these two directions are frequently indicated as most noticeable.
A study of the spine will make clear the fact that if the cartilage between any two Dorsal vertebrae be thinned in front the bodies of the vertebrae will be closer together and the spinous processes more widely separated; the spinous process of the upper vertebra will be crowded against the one superior to it and that of the lower against the one inferior to it. These spinous processes are said to be approximated.
The correction of S or I subluxations, then, depends upon correction of disturbed nutritive processes.