Elements of the principles and practice of midwifery . n the waters are discharged, the uterine contractions act withincreased force, and the head is forced down into the pelvic , at this point, much resistance is offered to its passage throughthe superior strait, the head becomes forcibly flexed upon the body?so that the chin is thrown up against the breast of the child. Thisconstitutes flexion, the object of which is to bring the occipito-bregmatic diameter into coincidence with the right oblique diameterof the pelvic inlet. The bi-parietal diameter still lies in the direc-tion of the
Elements of the principles and practice of midwifery . n the waters are discharged, the uterine contractions act withincreased force, and the head is forced down into the pelvic , at this point, much resistance is offered to its passage throughthe superior strait, the head becomes forcibly flexed upon the body?so that the chin is thrown up against the breast of the child. Thisconstitutes flexion, the object of which is to bring the occipito-bregmatic diameter into coincidence with the right oblique diameterof the pelvic inlet. The bi-parietal diameter still lies in the direc-tion of the left oblique pelvic diameter, and the occipito-bregmaticcircumference corresponds to that of the superior strait. Theaxis of the superior strait will traverse some point intermediatebetween the trachelo-bregmatic and occipito-mental diameters. Theeffect of this movement of flexion, is to change the position of thehead, so as to bring a smaller circumference of the childs headinto correspondence with the circumference of the superior strait. Fig. After flexion has been accomplished, the head is forced by thelabour-pains through the pelvic excavation to the lower strait of 176 VERTEX PRESENTATIONS. the pelvis. This constitutes the descent of the head, during whichthe parts within the pelvis undergo very great pressure. The de-scent of the head may be regarded as completely accomplished,when the occipito-bregmatic circumference is brought parallel tothe circumference of the perineal strait, but to effect this it is evi-dent, that the posterior parietal bone must traverse the whole depthof the posterior part of the pelvis, while the anterior traverses amuch shorter distance. The head of the child is now arrested in its progress by themuscles, &c, which form the floor of the pelvis. This resistanceis gradually overcome by the uterine contractions, during whichthe head is rotated, so that the occiput lies under the symphysispubis,—the sagittal suture is parallel with the ante
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
