A system of midwifery : including the diseases of pregnancy and the puerperal state / by William Leishman.
- William Leishman
- Date:
- 1876
Licence: Public Domain Mark
Credit: A system of midwifery : including the diseases of pregnancy and the puerperal state / by William Leishman. Source: Wellcome Collection.
65/882 page 35
![5. True Pelvh Briru, . Cavity, Outlet, Conjugate. 5* T 5 <Iblique. 5 [5i]t [4|] * Wliuu coccyx forced back. t The oblique diameters of the cavity and outlet arc placed in brackets, as, not being taken from fixed bony points, they aro of comparatively little importance. All the measurements given in this Table are, it must be remembered, those of the skeleton—no allowance being in any case made for the soft parts; and to them we may add another measurement, which has an important bearing on practical considerations arising from the study of a certain class of pelvic deformities. This is the sacro-cotyloid diameter, which is about 3| inches in a well-formed pelvis, and is represented by a line drawn from the centre of the sacral promontory to the region above the cotyloid cavity. The encroachment of the psoas and iliacus muscles, with investing and other structures, reduces the transverse diameter of the brim by about half an inch, while the other diameters of the brim, as well as of the cavity and outlet, are only reduced by an eighth to a epiarter of an inch at the most. The oblique diameters are least of all affected ; but, owing to the presence of the rectum on the left side, the left oblique diameter is slightly shorter than the right. These facts have to be borne in mind in the course of examinations which are made with a view of estimating the capacity of the pelvis in its various parts,—a question often of vital import in the practice of midwifery; and in such investigations it is also useful to know that the distance from the lower edge of the symphysis to the promontory of the sacrum is about half an inch more than the conjugate of the brim. In regard to the measure- ments numbered 2, 3, and 4 in the Table, if these are to be estimated by measurements in the living body, from two to three inches must be added for the tegumentary' and other external structures. In addition to the angles which have already been described as formed with the horizon by the planes of the brim and outlet, and measuring respectively 60° and 11° (Fig. 13), and the sub-pubic angle, there are several others which should not be overlooked. The sacro-vertebral angle is that which the sacrum forms with the upper portion of the vertebral column, and is estimated as 117° in the male, and 130° in the female. This remarkable contrast serves to show that there is no gain whatever in capacity by a sudden recession of the sacrum, and that they who have assumed that in the female' there is a more abrupt recession of the sacrum, are as much in error as those who have described the female sacrum to be more curved than the male. The symphysis forms with pie horizon an angle of 35° to 40° in the erect posture ; while the ischium forms with the ilium, or rather with the imaginary line leading down-](https://iiif.wellcomecollection.org/image/b20388792_0065.jp2/full/800%2C/0/default.jpg)
