The Growth of the Spinal Axis of the Human Body in Prenatal Life.

Abstract

It has been previously pointed out1, 2, 3 that the growth of the external dimensions of the human body in the fetal period is directly proportional to the growth in length of the body as a whole. The same law holds true for many of the lineal dimensions of the internal organs and parts, and is particularly well illustrated by the growth of the spinal column in prenatal life.We have studied these relationships by measurements of the total length of the spine and its parts in 148 specimens ranging from 2.5 to 55.0 cm. in total or crown-heel length, and have placed the results in the form of empirical formulae. These formulae were computed from the mean spine lengths for 5 cm. intervals of crown-heel length by the method of averages, weighting by the square root of the number of cases in each interval.In all instances we have found that the relationship of the spine and its parts with the total body-length is a rectilinear one which may be represented by the expression:where “S” is the length of the spine or...