Obstetrics : the science and the art / by Charles D. Meigs.

  • Meigs, Charles D. (Charles Delucena), 1792-1869.
Date:
1856, ©1849
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Licence: Public Domain Mark

Credit: Obstetrics : the science and the art / by Charles D. Meigs. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    This inclination of the sides of the pelvis, due to the position of the planes of the ischia, makes it inevitable for the head, when it hap- pens to present transversely, to spin on its axis and direct its longest diameter at last to the pubis in front and the sacrum behind. If it were not that the ischial planes are thus inclined, there would be no rotation, nor any need for it; but as it is, rotation is almost indis- pensable. A gestation would hardly go to term but for this inclina- tion: without it, the fruit of the womb would continually tend to drop down and be lost, in consequence of the upright attitude of the' woman. It makes her parturitions more painful than that of other creatures, but her compensation is found in the Ovidian privilege of the os sublime. A providential care has been manifested not only in this law of the inclination of the ischial planes, but is equally apparent in the planes of the pelvic canal. The Student has already been advertised that he ought not to adopt the notion that the pelvis has but the two planes; 1st. of the superior, and 2d. of the inferior strait; but rather, con- ceive of the entire pelvic canal from inlet to outlet as occupied with innumerable imaginary planes. Dr. Tyler Smith, in his Lectures on the Theory and Pract. of Midwifery^ Lancet, No. XIX., vol. i. 1856, after remarking that only the upper and lower planes have generally been deemed worthy of particular attention, says, but it is necessary to consider a third plane situated between the other two, and which may be termed the mid-plane, and he imagines this mid-plane''to be specially interesting, as being the point where the rotations of the head are impressed upon it. I have always considered that the flexed head in descending, commences its spiral or rotatory motion as soon as the occipito-frontal diameter begins to rest on opposite sides of the pelvic wall; that it descends rotating, and continues to do so until the crown of the head is pressed against the floor of the pelvis, when the rotation is, or rather, ought to be complete. Hence, I do not admit that there is, within the pelvis, any special plane, whether mid-plane or other that compels rotation. Indeed the whole trunk of the child, as well as the head, undergoes the spiral or rota- tory motion, and it cannot be that so important a portion of the pelvic function depends upon the so-called mid-plane. I present in Fig. 16 an illustration to show that the child is packed up in shape like an olive, and presents its cephalic or head-pole to the opening. If the head must of necessity suffer rotation in its progress, the trunk must do so no less, for it is true that this olive-shaped mass, about to be driven through the pelvic canal, is some twelve inches in length by a little less than four inches in its transverse diameter. For many years