The sexual differences of the foetal pelvis / by Arthur Thomson.

  • Thomson, Arthur, 1858-1935.
Date:
[1899]
Catalogue details

Licence: Public Domain Mark

Credit: The sexual differences of the foetal pelvis / by Arthur Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    as distinctive. The form of tlie inlet in the male is described as cordate, as contrasted with the more uniformly oval, elliptical, or reniform aperture in the female; this difference is due to the maximiun transverse width in the male being placed in a plane posterior to the greatest transverse diameter in the female. The same charactei'istic forms are seen in the foetal pelvis here figured, the shapes typical of the two sexes being readily recog- nisable as early as the fourth month. It has long been assumed, and the assumption has been based, no doubt, on the measure- ments of dried specimens, that the conjugate exceeded the trans- verse diameters in the foetal condition. According to Bimns,^ whose figures have been extensively quoted, it is not till about the tenth year that the tninsverse diameter exceeds the conju- gate. Hennig,2 in an elaborate paper on the child’s pelvis, has pointed out that such is not the ease, and confirms Fehling’s observations on the pelvis of the new-born child; yet, despite these researches, there seems to be a strong tendency to cling to the older accounts. In tlie four female foetal pelves which I have measiu-ed, the average transverse diameter of the brim was found to be 20‘8 mm., as comptired with an average conjugate of 17’5mm.; the four males yielded an average of 21'2 mm. for the transverse, and 17‘7 for the conjugate diameters. Verneau gives for adidt females the following averages: conjugate 106, and transverse 135 ; males, conjugate 104, transverse 130. Comparing these results, it will be seen that the differences between the conjugate and transverse diameters in the foetal pelves are very nearly pro- portional to the difference between the same measurements in the adult. Thus, in order to attain the adult proportions, there need only be an increase in width of 7 mm. in the female and 5 mm. in the male, supposing the foetal proportions are otherwise mainteined. The proportions of the conjugate diameters to the transverse in the series of foetal pelves has been estimated by means of the formula suggested by Zaaijer and employed by Sir W. Turner, viz.. Conjugate diameter x i^^ex. Trausveise diameter ' Ptinciples of Midimfery. - “ Das Kindliclie Bccken,” Archiv fur Anat. u, Entwickclungsgiscli^chte, 1880.