The science and art of obstetrics / by Theophilus Parvin.

  • Parvin, Theophilus, 1829-1898.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: The science and art of obstetrics / by Theophilus Parvin. Source: Wellcome Collection.

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    labor. These divisions have varied with different obstetric teachers. The late Dr. Hodge, for example, after the antero-posterior division of the pelvic cavity in the median line, had each half divided by a line beginning three-quarters of an inch in front of the sacro-iliac joint and extending downward to the extremity of the spine of the ischium ; thus two anterior and two posterior inclined planes were formed, and an object impinging upon either of the former rotated into the pubic arch, while if impinging upon either of the latter it rotated into the hollow of the sacrum. Other authors make the line of division between an- terior and posterior planes further forward. Still others, after dividing the pelvic walls into anterior, posterior, and two lateral walls, divide each of the latter—a lateral wall includes the part of the pelvis between the sacro-coccygeal surface and a line drawn from the ilio-pectineal emi- nence downward through the ischial tuberosity—into two inclined planes, the anterior and the posterior. Figs. 4 and 5 show the anterior wall of the pelvic cavity and the lateral inclined planes. Fig. 4. . Fig. 5. Anterior Pelvic Wall and Lateral Planes. It ought, however, to be said that few obstetric authorities now attach to these arbitrarily formed planes the importance in explaining the mechanism of labor which was once given them. Obliquity, Horizontal Planes, and Axes of the Pelvis. The pelvis is not in the axis of the body, a fact which is at once evi- dent when one observes that the sacro-vertebral angle is nearly four inches higher than the superior margin of the pubic joint, but it is placed obliquely with regard to that axis, and hence the expression inclination or obliquity of the pelvis. This obliquity is caused, first, by the form of the articulating face of the upper sacral vertebra, which is so oblique as to make an acute angle with the anterior surface of the body of the bone; second, by the shape of the cartilage between the sacrum and the lumbar vertebra with which it articulates; and finally by the obliquity of the innominate bones in their articulation with the sacrum; The result of this obliquity is that the weight of the gravid uterus is borne chiefly by the anterior abdominal wall and the superior border of the pubis. In order the better to show this obliquity of the