The science and art of obstetrics / by Theophilus Parvin.

  • Parvin, Theophilus, 1829-1898.
Date:
1891
Catalogue details

Licence: Public Domain Mark

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

    34/752 (page 28)
    imaginary transverse line passing through its second vertebra. Elevation of the pubic joint, or its equivalent forward movement of the superior part of the sacrum, lessens the antero-posterior diam- eter of the inlet, but increases the corresponding diameter of the outlet. On the other had, Mattei and Laborie assert an increase in the transverse diameter of the outlet by the wedge-like pressure of the fcetal head.1 But the form of the articular surfaces of the sacrum and the innominate bones is such—elevations upon the one fitting into depressions on the other, and the reverse—that any movement between these bones, whether it be described as rotation of the innominates upon the sacrum, or a movement of the base of the sacrum forward, while the lower portion of the bone moves backward, seems improbable, or impossible, in ordinary conditions. Moreover, the fixed position of the sacrum is further secured by its shape, and by the ligaments belonging to the sacro-iliac joint, and also by the sacro-sciatic ligaments, and by the ilio-lumbar ligaments. The shape of the sacrum, and the mode in which it articulates with the ossa innominata, render its position a secure and ordinarily an immovable one. 2 In so far as this movement of the sacrum, sup- posed usually to occur in all cases of labor, increases the coccypubic diameter, nature has provided a simpler method, which has been pointed out, and hence this is unnecessary. Uses of the Pelvic Joints.—Smcz, then, movements3 may be con- sidered as almost mil in the pelvic articulations, why is not this osseous girdle made of a single bone? The answer is that these joints have as their result the decomposition of forces, and thus prevent shocks and jars received by the lower limbs being trans- mitted directly to the vertebral column. Thus the uterus and the ovum as well as the prolongation of the spinal cord in the sacral canal are guarded from injury. These joints, especially the pubic are swelled during pregnancy, permitting a slight separation but such swelling is not for the increase of pelvic diameters, but tor providing against injuries from falls or jars ; they serve a purpose similar to that of the cushioned buffers of railway cars. The Pelvis as a Whole.-lts External Surface. This is of no great obstetric importance; still a few points are worthy of attention One feature of the pelvis is most striking-the great difference as to completeness between its anterior and its posterior portion. Behind, 1 Dr. Driver, in a paper read before the ^« the pelvic ligaments. 3 D L 2 Morris. . . tu„„ .;>rtiHr nrpmvmt women to ascertain * Budin [Progrls Medical, 1875 «^ ™° Tnml o fam nation was to in.ro- whether there were movements m the pubic joint The metnoa ox { ^ duce the index finger into the vagina and app y ^ P'^'^^ave her walk At each inferior margin of the joint while the subject was landing, and tnen ^ step she took he found that the finger was pushed down bV ^e/^ff,^ moved; the one or of the other side; that bone descend* which corres, onaea wi H- lu_ corresponding with the limb that was fi***™™^ of pregnancv a certain sions were, that in all pregnant women ^l^^J^^^ approaches it. end ; SnSsffi ^ thCTe wrverfconsiderable mobility the subjects walked without difficulty.