A treatise on the theory and practice of obstetrics.

  • Byford, William Heath, 1817-1890.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the theory and practice of obstetrics. 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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    V THE PELVIS. of view. The second part has been aptly named the true pelvis. It is of great importance that this true pelvis should be well understood by the accoucheur. When we look into the cavity of the pelvis from above downward, we see that the upper boundary, or superior strait, is shaped more like the heart of a playing-card than anything else, the large end behind at the sacrum, and the smaller before at the pubis. The excavation below this, for about two inches—at the sides—is more nearly, though not regularly, round. The brim is smooth and rounded instead of being sharp, and the cavity is polished and regular. Lower down on either side, and projecting slightly into the cavity of the pelvis, encroaching upon its dimension from a quarter to half an inch, are the spines of the ischium. They are lancet-shaped and hooked slightly inward. Just above them begins a concave surface that extends obliquely downward and forward to the ramus of the ischium— the plane of the ischum. By some authors it is called the ante- rior lateral inclined plane. The great sacro-sciatic notch lies behind and extends above it, and when filled by the soft parts forms a depression, and the term posterior lateral inclined plane has been ajDplied to it. The general direction of this concavity is towards the hollow of the sacrum behind. The anterior inclined plane is completed by the thyroid foramen when covered over by soft parts. It will be seen that a part of the posterior and ante- Fig. l. nor lateral inclined planes is formed of yielding tissue instead of firm bony structure. In addition to the fact that the oblique