The attitude and position natural and preternatural of the foetus in utero, acts of the reflex or excito-motory system / [Sir James Young Simpson].

  • Simpson, James Young, 1811-1870
Date:
1849
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Licence: Public Domain Mark

Credit: The attitude and position natural and preternatural of the foetus in utero, acts of the reflex or excito-motory system / [Sir James Young Simpson]. Source: Wellcome Collection.

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    * —— ee 36 DR SIMPSON ON POSITIONS OF THE F@TUS IN UTERO... yon aware, adverts or alludes to the strong and well marked reflex movements and actions performed during intra-uterine life by the motory muscles of the trunk, and particularly of the limbs of the foetus, and which constitute, as I have endeavoured to show, the mechanism by whose instrumentality nature ultimately effects and produces in the human uterus, the normal and salutary position of the child with the head downwards and over the os. At what period of intra-uterine life reflex movements first commence in these so- called voluntary muscles, we have no power of precisely determining. The exercise of these reflex movements is not essential for the prin- cipal object which they seem intended to accomplish (namely, the proper position of the foetus), till the latter period of pregnancy. But the foetus is usually felt by the mother moving as early as the middle term of utero-gestation; and stethescopic observations show that they are often present to some extent before they come to be per-- ceived at the time of quickening. “ During the early stage of preg- nancy,” says Negele, “while the foetus is very small in proportion to the size of the cavity which contains it, and while the free move- ments of its limbs are consequently unrestrained, sounds produced by the movements of the foetus may be occasionally distinguished as gentle taps repeated at intervals, and continued uninterruptedly for a considerable time. These sounds may sometimes be distinguished several weeks before the mother becomes conscious of the motion of © the child, and also earlier than the pulsations of the fcetal heart, or the uterine souffle.” + In comparative physiology, we may have even ocular proof of the early commencement of reflex or excito-motory movements in — the limbs, &c., of the embryo. In marsupial generation, the embryo, as is well known, leaves the uterus very early, and becomes immed- ately affixed to the nipple protruding in the interior of the marsupial sac, where it continues its development and growth. In the kan- garoo, the embryo is expelled from the uterus as early, according to the observations made by Professor Owen, as the thirty-ninth day. An embryo of the kangaroo expelled at that period, was watched and examined by Mr Owen, and to use his own words, it “resembled an earth-worm in its colour and semi-transparent integument,” and in the degree of development, its brain corresponded to that of the human embryo at the ninth week. Yet, in this early stage of development, the existence in it of reflex actions and movements was most distinct, for it breathed, moved its limbs when touched, and fixed upon the marsu- pial nipple. “It adhered freely,” says Mr Owen, “to the point of © the nipple; breathed strongly but slowly, and moved its fore legs ~ when disturbed.” ? . ~ 1 Treatise on Obstetric Auscultation, p. 50. 2 Cyclopedia of Anatomy—article Marsupialia—Vol. III., p. 322.