Elements of the principles and practice of midwifery . from the plane of one ischium to that of the other, measures about4£ inches. The inferior strait is oval in shape, and if we compare its dia-meters with those of the brim, the proportions will be found to bereversed ; though this change in proportion takes place gradually aswe advance through the excavation. The diameters are : 1. Theantero-posterior (AA, fig. 4), extending from the lower edge of the symphisis pubis to thepoint of the coccyx, mea-sures from 4 to 5 inches,allowing for the reares-sion of the coccyx. transverse diameter
Elements of the principles and practice of midwifery . from the plane of one ischium to that of the other, measures about4£ inches. The inferior strait is oval in shape, and if we compare its dia-meters with those of the brim, the proportions will be found to bereversed ; though this change in proportion takes place gradually aswe advance through the excavation. The diameters are : 1. Theantero-posterior (AA, fig. 4), extending from the lower edge of the symphisis pubis to thepoint of the coccyx, mea-sures from 4 to 5 inches,allowing for the reares-sion of the coccyx. transverse diameter(BB), extending from onetuberosity of the ischiumto the other, measuresabout 4 inches. 3. Theoblique diameter (CC),which passes from themiddle of the sacro-sciatic ligament of one side, to the point of unionbetween the ramus of the ischium and pubis, of the opposite side,and measures about 41 inches. By a reference to figure 5, it will be observed that the axis of thesuperior strait (ab) is not in a line with that of the body (cd), for while PiK. THE PELVIS. 35 Fig. 5. the former passes downward and back,ward, the latter falls upon the symphisispubis. Ramsbotham has stated veryclearly the advantages of this arrange-ment, he says: Were the axis of thetrunk and the pelvic entrance in thesame line, owing to the upright condi-tion of the human female, the womb,towards the close of gestation, wouldgravitate low into the pelvis, and pro-duce most injurious pressure on thecontained viscera, while, in the earlymonths, not only would the same dis-tressful inconvenience be occasioned,but there would be great danger of itsprotruding externally, and appearing asa tumour between the thighs, coveredby the inverted vagina. We mayalso add, that even in the non-pregnantstate, the pelvic viscera would, but forthis arrangement, be liable to constantprolapsus; both from the effect of gra-vity, and from the weight of the super-incumbent viscera of the these advantages are import
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
