Acupuncture points affect therapeutic treatment results, and therefore, precision in their location is of great importance. The earliest record of proportional measurements to locate points can be found in Chapter 14 of the Celestial Pivot. The length and width of physical proportions are divided into equal, definite units determined by each patient’s own anatomical landmarks and the equivalent spaces in between.
Divisions are made by the second finger phalange of the index finger of the patient, and are a standard for point location.
The measurement of the width of their thumb joint would also equal one cun.
A four finger width measurement is used to locate acupuncture points who’s locations lie on the 4 limbs and the abdomen.