In recent times it is generally customary to assume that the HACHIRYO points correspond with the posterior sacral formina. In order to find a way to locate these points in accordance with this general practice we took X-rays of the sacral area of 23 subjects and conducted this study. Results showed that the standard height for the distribution of the HACHIRYO points was a point halfway between the spinous process of the 5th lumbar vertebra and the superior ridge of the middle sacral crest. We called this point the “17th vertebra”. Also the midpoint between the inferior ridge of the left and right sacral angles was determined as the “sacral angle midpoint”.
One-fourth of the way from the 17th vertebra to the sacral angle midpoint was considered the height of B-31. In the same area onetenth of the way from the sacral angle midpoint to the 17th vertebra was determined as the height of B-34. The area between B-31 and B-34 is divided into thirds to determine the heights of B-32 and B-33.
Next to determine the lateral distribution the area between the inferior ridge of the posterior-superior iliac spine and the posterior median line is used. The point laterally 3/4 of the way between these which coincides with the predetermined height of B-31 is the location of B-31. Likewise the point halfway between the inferior ridge of the posterior-superior iliac spine which coincides with the determined height of B-34 is the location of B-34. Next a slanted line is used to connect B-31 and B-34. The points along this line which coincide with the previously determined heights of B-32 and B-33 are considered the locations of these points.