A system of obstetrics . f the terminal points of the conjugata vera. The antero-posterior and transverse diameters of the outlet become unusually large-in comparison with the contraction at the inlet. The Mechanism of Labor in the Simple Flat and in the Rachitic FlatPelvis.—In consequence of the narrowing of the pelvic inlet in theconjugate, the head of the foetus not only does not enter the pelviccavity, as is the rule in the last weeks of pregnancy in primigravidre,but it is turned aside at the brim, and hence the proportion of trans-verse presentations is increased. Another factor in causi
A system of obstetrics . f the terminal points of the conjugata vera. The antero-posterior and transverse diameters of the outlet become unusually large-in comparison with the contraction at the inlet. The Mechanism of Labor in the Simple Flat and in the Rachitic FlatPelvis.—In consequence of the narrowing of the pelvic inlet in theconjugate, the head of the foetus not only does not enter the pelviccavity, as is the rule in the last weeks of pregnancy in primigravidre,but it is turned aside at the brim, and hence the proportion of trans-verse presentations is increased. Another factor in causing such mal-position of the feetus is found in multigravidse in the relaxed abdominalwall, which permits anterior displacement of the uterus. If the pelvisbe below, its descent through the narrowed aperture does not occur, butthe feet are prone to enter. Supposing the head to be at the inlet whenlabor begins, this takes a transverse position ; that is, the sagittal suture 736 ANOMALIES OF THE FORCES IN LABOR. Fig. instead of being oblique lies directly from one side toward the other ofthe pelvis. Eesistance to the descent of the occiput compels a partialdeflection, and the anterior and posterior fontanelles are in about the same pelvic plane; thus the transverse diam-eter of the foetal head is in the pelvic con-jugate, and the occipitofrontal in the pelvictransverse. But in this accommodation theanterior parietal is somewhat in advance ofthe posterior, and therefore the sagittal sutureapproaches the sacral promontory. (See ) The anterior parietal bone, pressed againstthe anterior pubic wall, becomes the fixed piv-otal point around which a partial revolution ofthe posterior parietal occurs in the descent untilthe promontory is cleared. But in order thatthis descent can occur, the transverse diameterHead passing through the inlet 0f the head must be lessened ; this lessening is in Flat Pelvis. ,. , , . , , . ° _ in part accomplished by the lateral margin ofthe po
Size: 1337px × 1868px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
