The tubercle (Chassaignac’s) of the sixth Cervical transverse is said to be directly opposite the lower border of the cricoid cartilage and this is a better guide than the above.
The third Dorsal spinous process is said to be on a level with the root of the spine of the scapula, and with arms hanging at sides, the upper angle of the scapula to be on a line between first and second Dorsal spinous process. This is not at all constant.
The inferior angle of the scapula is said by some writers to be on a line with the tip of the seventh Dorsal spine. Others locate it opposite the interspace between seventh and eighth Dorsals. Still others give it as opposite the eighth Dorsal spine. All are correct—sometimes. In truth, the inferior angle may be opposite any part of the spine between the sixth and ninth Dorsals. There is nothing constant about it.
The twelfth rib may be followed to its articulation with the twelfth Dorsal vertebra. This is a good guide, providing that the rib can be palpated. The lower margin of the last rib is usually even with the spinous process of D 12 about one inch and a half from the mid-spinal line. The humor lies in the fact that the patient upon whom the count is so difficult as to require this verification is usually obese and obesity renders the rib impalpable.
The line drawn between the iliac crests falls between the third and fourth Lumbar spinous processes in about 98% of all cases. This is our most reliable landmark. It is used as described under the Count.
All landmarks except the last two show such variance in different individuals as to be quite unreliable. The correct method of numbering spinous processes is the obvious and logical method—count them. The skill and accuracy of touch required for successful counting is invaluable in determining direction of subluxations.
MENTAL ATTITUDE
In order to secure that absolute concentration without which it is impossible to appreciate properly those tactile impressions for the very reception of which such continued practice is necessary, the hands should leave the spine as little as possible during palpation; a second person should record subluxations found so that the palpater need only state, and not write, his conclusions; light pressure on the spine should always be used, as a heavy pressure desensitizes nerve-endings in the fingers; and silence should be maintained except for the necessary statement of points to be recorded.