. The science and art of midwifery. naturally pursue in itscourse through the parturient canal. In practice it is convenientto follow the suggestion of Hodge, and draw a plane from the supra-pubic ligament backward to the sacrum, and parallel to the plane ofthe superior strait. This second parallel would intersect the middleportion of the second sacral vertebra. Inasmuch as the pubic wallsrun nearly parallel to the upper portion of the sacrum, the axis of thecavity included between the two planes may be regarded as continu-ous with the axis of the brim. Below the second plane, owing to thecurv
. The science and art of midwifery. naturally pursue in itscourse through the parturient canal. In practice it is convenientto follow the suggestion of Hodge, and draw a plane from the supra-pubic ligament backward to the sacrum, and parallel to the plane ofthe superior strait. This second parallel would intersect the middleportion of the second sacral vertebra. Inasmuch as the pubic wallsrun nearly parallel to the upper portion of the sacrum, the axis of thecavity included between the two planes may be regarded as continu-ous with the axis of the brim. Below the second plane, owing to thecurvature of the sacrum, the axis describes a nearly circular course^with intersecting planes radiating from the lower border of the sym-physis as a center. Further on it will be shown that the axial curve iscontinued beyond the bony canal by the distended tissues which formthe floor of the pelvic basin. Differences between the Male and Female Pelvis.—In the male thebones of the pelvis are thick and solid ; the brim is triangular in. Fig. 99.—Axis represented upon avertical section through a plastercast of the pelvic cavity. (Hodge.) MECIIAXISM OF LABOR. 161 shape ; the promontory projecting ; the cavity deep, and sloping in-ward like a funnel; the sacrum long, narrow, and moderately curved ;and the arch of the pubes is formed at an angle of from 75° to 80°.In the female, on the contrary, the bones are lighter and more delicatein contour, therein corresponding to the inferior muscular develop-ment of the sex ; the brim, owing to the less marked jutting inwardof the promontory, has an ellij^tical outline ; the diameters, bothantero-posterior and transverse, are increased ; the pelvic inclinationis more pronounced ; the sacrum is wider and more concave ; thetuberosities of the ischia are wider apart; the angle of the arch of thepubes measures from 90° to 100° ; and the entire depth of the pelvisis diminished. As a result of the increased transverse diameter in thefemale, the
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Keywords: ., bookcentury1800, bookdecade1890, bookidsci, booksubjectobstetrics
