. Cunningham's Text-book of anatomy. Anatomy. The accentuation of the pontine flexure at this stage brings the two cerebellar rudiments into the transverse direction and in line one with the other and the roof-plate, which is now being thickened by immigrant neuroblasts from the medial extremities of the two cerebellar rudiments. When one organ is thus formed by the union in the roof-plate of the originally separate rudiments, it presents the form of a dumb-bell shaped mass (Fig. 503). Upon the inferior aspect of this mass there is a slight ridge, to which the tela chorioidea ventriculi quarti
. Cunningham's Text-book of anatomy. Anatomy. The accentuation of the pontine flexure at this stage brings the two cerebellar rudiments into the transverse direction and in line one with the other and the roof-plate, which is now being thickened by immigrant neuroblasts from the medial extremities of the two cerebellar rudiments. When one organ is thus formed by the union in the roof-plate of the originally separate rudiments, it presents the form of a dumb-bell shaped mass (Fig. 503). Upon the inferior aspect of this mass there is a slight ridge, to which the tela chorioidea ventriculi quarti is attached. Opposite the lateral cerebellar rudi- ments (but not in the median plane) the attach- ment of the tela becomes thickened to form the posterior medullary vela. Early in the third month the growth of the cerebellar rudiment begins to manifest itself by lateral bulgings of its surface. The rhombic lip, the inferior part of which has been seen to play an important part in the development of the nuclei pontis and nucleus olivaris inferior, is also continued upwards beyond the pontine flexure on to the cerebellar rudiment, FlG- aspect of the Rhomb- , r ., „ , „ . m, ENCEPHALON IN A HUMAN EMBRYO. where it lorms a margmal fringe. Ihus even in the second month a groove can be detected upon the cerebellum separating off a band which is continuous with the tuberculum acusticum. The part nearest to the latter represents the rudiment of the flocculus and the medial extremity the nodulus (Fig. 503). During the third month the cerebellum appears as a rounded bar transversely placed across the upper part of the roof of the fourth ventricle, and as the lateral extremities of this bar expand (Fig. 504), it assumes a dumb-bell shape not unlike that presented a few weeks earlier (Fig. 503) on its ventricular aspect. As these lateral bosses (lobi laterales) develop, a mass of transverse fibres in connexion with them also becomes apparent. It represents the fibrse trans
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
