Elements of the principles and practice of midwifery . e posterior or lateral positions of the chin so dif-ficult, and forms the most important peculiarity in the mechanismsof the different face positions. All these positions would be nearlyequally favourable, were it not for this circumstance. A glance atthe two figures will indicate our meaning. In figure 19, the chinhas made its appearance from underthe symphysis pubis, while the bodyof the inferior maxillary bone is ap-plied to its posterior face, so thatwhen arrived at this point, the headbecomes flexed, and the face, fore-head, and verte
Elements of the principles and practice of midwifery . e posterior or lateral positions of the chin so dif-ficult, and forms the most important peculiarity in the mechanismsof the different face positions. All these positions would be nearlyequally favourable, were it not for this circumstance. A glance atthe two figures will indicate our meaning. In figure 19, the chinhas made its appearance from underthe symphysis pubis, while the bodyof the inferior maxillary bone is ap-plied to its posterior face, so thatwhen arrived at this point, the headbecomes flexed, and the face, fore-head, and vertex are delivered, (as isshown in the linear representation inFig. 19,) without bringing the longoccipito-mental diameter of the foetalhead into correspondence with theantero-posterior diameter of the pel-vic cavity orof the inferior strait. Itis easily understood, that where thechin fails to be rotated under the symphysis pubis, the mechanism will be, if the head is full size,impossible, because the occipito-mental diameter of the head must18 Fig. 206 PRESENTATIONS OF THE PACE. at some period of the process, offer to the antero-posterior dia-meter of the inferior strait of the pelvis. It may be laid down asa positive rule, that in all face presentations, the chin should rotatetowards the symphysis pubis ; that when the efforts of nature orartificial means, fail to accomplish this, the delivery, in a full-grown faztus, will be rendered almost, if not utterly impossible. After the face has descended as far as the length of the neck ofthe child will permit, rotation occurs, by which the chin first makesits appearance under the symphysis pubis, while the body of theinferior maxillary bone, and finally the neck of the child, is appliedto the posterior part of this symphysis. The body, in this case,has not yet entered the pelvic excavation. (See Fig. 19, above.) The movement of descent and rotation having been completed,the flexionof the head commences. At this time the position
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Keywords: ., boo, bookcentury1800, booksubjectmidwifery, booksubjectobstetrics
