. The science and art of midwifery. o ex-tensive modification as they are subjected to the resistance of the par-turient canal. Of these the most important is the diminution of thesub-occipito-bregmatic, the occipito-frontal, and the bi-temporal diam-eters, with compensatory elongation taking place in a line runningfrom the chin to a point in the sagittal suture situated between theapex of the occipital bone and the large fontanelle (maximum diame-ter of Budin). The plastic changes mentioned are rendered possibleby the presence of the fontanelles, the width of the sutures, the plia-bility of t
. The science and art of midwifery. o ex-tensive modification as they are subjected to the resistance of the par-turient canal. Of these the most important is the diminution of thesub-occipito-bregmatic, the occipito-frontal, and the bi-temporal diam-eters, with compensatory elongation taking place in a line runningfrom the chin to a point in the sagittal suture situated between theapex of the occipital bone and the large fontanelle (maximum diame-ter of Budin). The plastic changes mentioned are rendered possibleby the presence of the fontanelles, the width of the sutures, the plia-bility of the sagittal borders of the parietal bones, the depressibility ofthe os frontis, and the joint-like movement between the squamous andbasilar portions of the occipital bone. As a consequence of these ana- MECHANISM OF LABOR. 187 tomical dispositions, pressure from above inclines the frontal bones back-ward, while the resistance encountered below shoves the occipital bonein a forward direction. These movements are rendered possible by. Fig. 118.—Outlines showing difference between head of child at birth (1) and four days sub-sequent to delivery (2). ( the depression of both frontal and occipital bones beneath the adjacentborders of the parietal bones ; at the same time the dragging thus ex-erted upon the latter, front and rear, increases the curve of the cranialvault along the line of the sagittal suture. The sharpness of the bendat the summit of the curve is more or less pronounced, according tothe rigidity of the channel through which the head passes. In casesof birth with the occiput to the rear, the head is often drawn out to agreat length, the occiput forming an almost vertical line with theneck and shoulders, while in front the forehead and parietal bonesslope upward to the vertex in nearly the same plane. (Fig. 119.) The contour of the head is still further modified by the formationof the caput succedaneum, or scalp-tumor, a swelling developing uponthe portion of t
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Keywords: ., bookcentury1800, bookdecade1890, bookidsci, booksubjectobstetrics
