한국인태아 외이도, 고막 및 이소골의 발육에 관한 연구

Abstract

The measurements of various items on the external auditory meatus, anulus tyrnpanicus. tympanic membrane and auditory ossicles have been done on 456 cases(252 of male, 204 of female) of Korean fetuses aged from 4th month until 10 th month. Beside the monthly and sexual averages on each of the items, the various indices of the above measurements over the body weight and the body length are calculated for analysis of the developing pattern. 1. The normal mean value of each of the measurements is presented. 2. The velocity of the increment of each of various diameters, such as, lengths, widths and thicknesses in successive fetal months is comparatively rapid until 6th month, and it is relatively slow after 6 th month. 3. To the contrary, gain of weight in each of various measured weights is slow until 7th month, and then. it is rapid after 7th month. 4. Index of each of the various diameters to the body length at the 5th month is continuously decreased with the time until 10th month. 5. Index of the weight of anulus tympanicus to the body weight is increased rapidly in successive fetal months after 7th month, whereas, that of the stapes is decreased rapidly. Those of the mal1eus and incus at 8th and 9th month, however, are shown a relatively high value and are followed by a regression at the last month, 6. The ossification of each of the auditory ossicles is completed before birth. Among them, those of the head and neck of the malleus, and body of the incus are completed at 7th month, while those for the rest of them are completed at 10th month. 7, On the above measurements none of the sexual differences are considered.