. Quain's Elements of anatomy. cipitalregion increases as the cerebrum extends backwards (Cleland). At the time of birth theparietal region has reached its largest development in proportion to the occipital and frontalregions. The greatest frontal breadth is then smaller in proportion to that between theparietal eminences than afterwards. The base of the cranium is relatively small, and thegreat wing of the sphenoid and the temporal squama do not extend so far upwards as subse-quently is the case. The petrous, which is. however, comparatively large, is inclined moreforwards than in the adult.
. Quain's Elements of anatomy. cipitalregion increases as the cerebrum extends backwards (Cleland). At the time of birth theparietal region has reached its largest development in proportion to the occipital and frontalregions. The greatest frontal breadth is then smaller in proportion to that between theparietal eminences than afterwards. The base of the cranium is relatively small, and thegreat wing of the sphenoid and the temporal squama do not extend so far upwards as subse-quently is the case. The petrous, which is. however, comparatively large, is inclined moreforwards than in the adult. Other peculiarities, such as the existence of the fontanelles, theprominence of the frontal and parietal eminences, and the absence of the mastoid processes,have been referred to in describing the development of the several bones. The face at birthscarcely reaches an eighth of the bulk of cranium, while in the adult it is at least a half(Froriep). The skull grows rapidly during about the first seven years of life. By that time. Fig. 83.—Lateral view op the childs skull atBIRTH. (Leishman.) -g This figure shows the elongated form of the skull inthe infant, and the small proportion which the facialbears to the cranial part, and also the lateral fontanellesat the lower angles of the parietal bones. The lines indi-cate the various diameters. certain parts, including the circumference of theoccipital foramen, the body of the sphenoid, thecribriform plate, and the petrous division of thetemporal, have attained their definitive size. Theother regions also increase but little until theapproach of puberty, when a second period ofactive growth begins, affecting especially the face and the frontal portion of the cranium,with which is associated the expansion of the frontal and other air-sinuses (Merkel). Theface becomes elongated in the progress of growth, partly by increased height of the nasalfossas and adjacent air-sinuses, partly by the growth of the teeth and the enlargement of the
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectanatomy
