Elements of the principles and practice of midwifery . ect the various points of diagnosis towhich we have alluded. Soon after the rupture of the bag of waters, the expulsion com-mences, the mechanical phenomena of which are executed in thefollowing order. The uterine contractions becoming more violent, force the face downward into thepelvis, and the extension of thehead becomes much this extension has beenperfected, and the face has fairlyentered the brim, the relation ofthe parts are as follows: thefronto-mental diameter corres-ponds to the transverse diameterof the upper stra
Elements of the principles and practice of midwifery . ect the various points of diagnosis towhich we have alluded. Soon after the rupture of the bag of waters, the expulsion com-mences, the mechanical phenomena of which are executed in thefollowing order. The uterine contractions becoming more violent, force the face downward into thepelvis, and the extension of thehead becomes much this extension has beenperfected, and the face has fairlyentered the brim, the relation ofthe parts are as follows: thefronto-mental diameter corres-ponds to the transverse diameterof the upper strait; the bi-tempo-ral to the antero-posterior of thesame, while the mento-frontalcircumference offers to that of thepelvic brim. The position of thebody of the child is not at allchanged. The axis of the pelviswill now traverse a line drawn from the posterior fontanelle to thesuperior lip of the foetus. (See fig. 18.) When extension has been accomplished, the face descends intothe cavity of the pelvis, to the extent permitted by the length of Fig. PRESENTATIONS OP THE FACE. 205 the neck of the child. It is evident it can go no further, for if itdid, the head and a portion of the breast of the child would be con-tained within the pelvis at the same time—a thing impossibleunder ordinary circumstances. But if its descent is limited by thelength of the neck, the face cannot descend, as the vertex does, tothe floor of the pelvis, because the length of the neck of the childdoes not reach three inches, which is the depth of the lateral partof the pelvis. The face, then, in its descent, must stop at somepoint short of the pelvic floor, when its rotation commences. Thisrotation usually brings the chin under the symphysis pubis, andthis is a point of great importance, for if the chin is not turned inthis position, the difficulties of the delivery will be immense, sinceit will cause the longest diameters of the foetal head to correspondwith the long diameter of the inferior strait.
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
