On the development of the female pelvis / by J. Matthews. Duncan.

  • James Matthews Duncan
Date:
1859
Catalogue details

Licence: Public Domain Mark

Credit: On the development of the female pelvis / by J. Matthews. Duncan. Source: Wellcome Collection.

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    The pelvis, during its growth, is subjected, in the manner to be afterwards described, to very powerful forces, and, at the same time, it also undergoes considerable changes of shape. It will be shown that these changes of shape correspond to the forces in every ascer¬ tainable respect. But before proceeding to show the relation of the forces to the shape produced, it is necessary to say a few words by way of illustrating how mechanical forces affect the shape of healthy bones. It is surely indisputable that the healthy growing pelvis, as a whole, with its joints and with the Y shaped cartilages separating the cotyloid ends of the three parts of each os innominatum, is greatly under the control of the great forces to which it is for long periods subjected: and this admission is sufficient ground for the explana¬ tion of its development to be afterwards given. A somewhat apposite illustration of this kind of change of form is found in the spinal column, which in the young child is almost straight, but, under the influence of the weight to which it is subjected, assumes the curves natural to it in adult age. But it is quite consistent with our general knowledge of the physiology of bone, that, under powerful and continued forces, even the healthy bones themselves undergo changes of form.1 The human skeleton is so arranged as to have, in the adult at least, suffi¬ cient power to resist almost every tendency to change of form from this cause. But, even in the adult, the weight of the body acting at an extraordinary advantage on the neck of the femur, effects in it a slow change of shape, so that it is virtually bent upon the shaft, gra¬ dually forming with it a less and less obtuse angle, and from this and other causes combined, it becomes more and more liable to fracture. The iliac beam may be regarded as a long bone, strengthened by the apposition of its ala. The weight or force to which it is sub¬ jected acts upon it at its two extremities, and not in the direction of its length, and with a degree of vantage not to be observed in any other bone of the body. It does, while growing, change in form under these forces, and, I believe, in consequence of them. A like authority of Davy, Schreger, and others, that there is a progressive and con¬ siderable increase in the earthy constituents of the bones with advancing years. This, however, would seem to be by no means universally true. Dr Bees finds it to be the case with regard to the long bones, and the bones of the head ; those of the foetus not containing the excess of earthy matter which he discovers in those of the adult. But the bones of the trunk in the foetal skeleton appear, from his analyses, to be as rich in the proportion of earthy matter as those of the adult.” 1 That this pressure is without influence in the healthy skeleton appears to be the view expressed by Mr Moore, in a valuable paper on this subject, published in the British and Foreign Medico- Chirurgical Review for July 1857. u But (he says) it is surely erroneous to say that bones depend upon pressure for their regular development. Undue pressure may deform them, but not that whsch they are made to resist: had they no power of growing into a definite shape, and maintaining it, they would be incapable of bearing the very forces to which they are ordinarily subject.”
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