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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    part. In very fat women the perineum does not yield readily in labor, and hence the liability to its rupture; while in some other patients it yields too readily, and its anterior margin is prolonged toward the pubic arch, while its central portion is so thinned that it may be per- forated by the child's head, that is, a central rupture occur. Pubic and Sacral Segments of the Pelvic Floor. The pelvic floor, in its relations to labor, is divided by Hart1 into two parts, designated respectively the pubic and the sacral segment. The anterior vaginal wall is the posterior boundary of the former segment, and the posterior vaginal wall the anterior boundary of the latter segment. In labor the anterior segment is drawn up, while the sacral segment is forced down ; and thus, as two doors meeting at their free border are opened, the one by drawing it toward the passenger, the other by pushing it from him, so the pelvic floor is opened for the transmission of the foetus. Fig. 17. Anteroposterior Section of the Aponeuroses of the Perineal Floor. S. Sacrum. A P. Pelvic aponeurosis. B. Deep perineal aponeurosis. C. Middle perineal apo- neurosis. D. Superficial perineal aponeurosis. E. Connective-tissue layer which covers the lower surface of the levator ani behind the bis-ischiatic line, where it is fused with the posterior border of the deep perineal aponeurosis. P. Pubis. The vagina passes through the pelvic floor parallel to the conjugate of the inlet. The Dynamic Pelvis. From the parallelism of the vagina, as it passes through the pelvic floor, with the antero-posterior diameter of the inlet, it necessarily follows that if the presenting pole of the foetus enters the inlet in a line perpendicular to its plane, the emergence of that pole from the vagina will be in a line perpendicular to the prolonged previous line. Hence, according to the view of Boissard and some others, a curved line does not represent the line of direction taken by the pre- ' Female Pelvic Anatomy.