The principles and practice of obstetrics / by Hugh L. Hodge.

  • Hodge, Hugh L. (Hugh Lenox), 1796-1873.
Date:
1864
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Licence: Public Domain Mark

Credit: The principles and practice of obstetrics / by Hugh L. Hodge. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    peau, Stoltz, Nsegele, otc, to give a moro full idea of the dimensions of the superior strait, in reference espe- cially to deformities which are occasionally found in practice. They may be termed the sacro-acetabular or B&cro-cotyloid diameters. They run from the centre of the promontory of the sacrum to that portion of the linea ilia opposite to the central portion of the ace- tabula, and measure, in the healthy female, three and a quarter inches. The plane of the superior strait must be regarded as a mere surface, bounded by the circumference just de- scribed. It does not encroach on the cavity of the pelvis, in the same manner as a window does not en- croach upon the size of a' room; it is a mere orifice or opening from the superior into the lower pelvis. The axis of this plane is, of course, represented by a line drawn through its centre, at right angles to its surface. This line, when prolonged, will strike inferi- orly toward the termination of the coccyx, and ante- riorly, or superiorly, will pass out of the body, through the linea alba, below the umbilicus. (Plate I., Fig. 3.) It is apparent, therefore, that the space around the coccyx is directly parallel or opposite to the plane of the superior strait. It may be termed the coccygeal region, or plane. It is, in reality, the bottom of the pelvis. Inferior Strait. — The inferior strait of the pelvis, the opening, outlet, or exit, is smaller than the supe- rior, more irregular in its form, but may nevertheless be regarded as presenting an elliptical surface with its circumference, diameters and axis. (Plate L, Fig. 2.) The circumference is bounded anteriorly by the sub- pubic ligament; on either side by the inner margin of the rami of the pubis and of the ischium, and of the tuber of the ischium; and posteriorly by the margin of the inferior sacro-sciatic ligaments and the extremity of the coccyx. This circumference measures twelve inches. It is irregular, owing to the triangular projec- tions of the bodies of the ischia laterally, and of the coccyx and connecting ligaments posteriorly. Practi- cally, however, it may be regarded as a simple plane, through which the child passes on its exit from the pelvis. (Plate II., Fig. 9.) The diameters to be studied are four in number: one, the long diameter, extending from the os coccygis to the sub-pubic ligament, and therefore termed the antero-posterior or coccy-puhal diameter. It measures four and a half inches during labor, when the coccyx is extended, but only four inches when this bone is at r.>t. The transverse or conjugate diameter extends from the inner margin of the tuber of the ischium, on one side to the opposite, and is hence termed the bis- uschiatic diameter: it measures four inches. The oblique diameters are of less importance; they extend from the right or left junction of the rami of the pubis and ischium to the middle of the inferior sacro-sciatic ligament, on the opposite side, and measure also four inches. The plane of the inferior strait is not easily de- scribed, inasmuch as from the pubis to the coccyx, if we follow the projections of the ischia, it is a convex surface; practically, however, it may be described as an oval opening, the long diameter, owing to the retro- cession of the coccyx during labor, being antero-poste- rior, and the short diameter being transverse. At the posterior portion of this ovoid surface is a triangular indentation made by the os coccygis; while laterally the triangular bodies of the ischia project below the level of the plane, that is, below the sub-pubic liga- ment and the coccyx. This plane, like that of the superior strait, is to be regarded as a mere surface, without depth or thickness. Its cms is represented by a line drawn perpendicularly through the centre of. the plane, midway between the pubis and the coccyx, which, when prolonged, will strike the promontory of the sacrum; when, however, the coccyx is pushed back, during the passage of the child's head, this axis, in its prolongation, will strike the first bone of the sacrum. (Plate L, Fig. 3.) The Cavity of the Pelvis. — The cavity, basin, or canal of the pelvis, includes all the space between the superior and inferior straits. It is an irregular pas- sage, contracted at its superior and inferior openings, but enlarged below the promontory of the sacrum by the concavity of the latter. It is slightly curved ante- riorly, and its superior strait is oblique to the inferior. The degree of obliquity is measured by the angle made by the junction of their planes when extended beyond the pubis. (Plate III., Fig. 23.) This angle, although varying much in different subjects, may be considered as equal to fifty degrees. Of course, the axis of the superior strait and that of the inferior will decussate in the pelvis at the same angle. The depth of the pelvis anteriorly at the symphysis pubis is one inch and six lines; posteriorly, from the promontory of the sacrum to the os coccygis, it mea- sures about four inches and nine lines, or, when the coccyx is extended, as in labor, five inches. The lateral depth, from the tuberosity of the ischium to the linea ilia, is three and a half inches. It thus appears that the depth of the pelvis rapidly increases from the ante- rior to the posterior portion. As has been already mentioned, the sacro-pubic diameter of the superior strait measures four inches, but a line drawn from the sub-pubic ligament to the promontory of the sacrum measures four and a half