. Journal of anatomy . of the neck(made up of mastoid and occipital segments); (2) there is the growth ofthe basilar plate of the skull—basi-occipital and basi-sphenoid—whichappears to thrust the occipital condyles backwards (see fig. 9), but inreality pushes the facial part of the skull forwards; (8) there is anabsorption or atrophy of that part of the occipital squama that bounds the Description of a New Craniometer, etc. 265 foramen magnum behind. These changes are given a diagrammatic repre-sentation in figs. 8 and 9. In the composition of these figures I utilisedthe measurements made in o
. Journal of anatomy . of the neck(made up of mastoid and occipital segments); (2) there is the growth ofthe basilar plate of the skull—basi-occipital and basi-sphenoid—whichappears to thrust the occipital condyles backwards (see fig. 9), but inreality pushes the facial part of the skull forwards; (8) there is anabsorption or atrophy of that part of the occipital squama that bounds the Description of a New Craniometer, etc. 265 foramen magnum behind. These changes are given a diagrammatic repre-sentation in figs. 8 and 9. In the composition of these figures I utilisedthe measurements made in our 130 anthropoid skulls, more than 70 ofwhich were immature. The growth of the nuchal area is greatest in the gorilla. With theascent of the temporal ridges on the sides of the skull there is a corre-sponding movement in the nuchal lines over the occipital and mastoid partsof the skull, to give increased attachment to a rapid growth in the musclesof the neck. These changes are shown in fig. 8. From the eruption of. »d. V \ fr\^^^^^ . Fig. 8. — Diagram of the growth of the nuchal crests in tlie gorilla from youth (milk-dentation) to old age. The occipital bone of the young gorilla is shaded, and theposition of the occipital part of the nuchal ridge or line is shown at X^^ (the inion) ;the jiosition in the adult at X\ The distance between X- and X- represents thedegree of lateral expansion from youth to maturity. The corresponding expansion inman is shown bj^ H. the milk teeth to the close of the permanent dentition the nuchal ridgeascends on the occipital bone of the gorilla to an extent of 80 mm., untilit meets with the temporal ridge and forms, by their fusion, the lambdoidalcrest. The ascent in the male orang is 75 mm.; in the chimpanzee 47 mm.;in man 30 mm.; in the gibbon 30 mm. In all the giant primates—man,gorilla, chimpanzee and orang—the neck is about equally thick at birth andthe area of nuchal attachment approximately equal. The nuchal expansionis g
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
