Quain's elements of anatomy . bres are smaller than the longitudinal. The interspersed grey matterseems to correspond to that which is found between the arcuate fibres ofthe medulla. The posterior or dorsal portion of the pons is chiefly constituted by acontinuation upwards of the formatio reticularis and of the grey matter ofthe medulla oblongata. As in the latter, there exists here also a medianseptum or raphe, which is similar in structure to that of the does not extend through the ventral half, being obliterated, or nearlyso, by the great development of the transverse or commiss
Quain's elements of anatomy . bres are smaller than the longitudinal. The interspersed grey matterseems to correspond to that which is found between the arcuate fibres ofthe medulla. The posterior or dorsal portion of the pons is chiefly constituted by acontinuation upwards of the formatio reticularis and of the grey matter ofthe medulla oblongata. As in the latter, there exists here also a medianseptum or raphe, which is similar in structure to that of the does not extend through the ventral half, being obliterated, or nearlyso, by the great development of the transverse or commissural fibres,€scept near the upper and lower borders where the superficial transverse THE POXS VAEOLII. 301 fibres of the pons turn in at the middle Hne ; and especially at the upperborder where bundles of the same fibres encircle the crm-a cerebri as theyemerge from the pons. In the reticular formation, in addition to the scattered and reticularlyarranged grey matter ^th nerve-cells everywhere met -with, there are Fig. Pig. 272.—Section across the pons at about the jiiddle op the fourth ventricle(after Stilling and Schwalbe). f py, pjrramid-bundles continued up from the medulla ; ^90, transverse fibres of the ponspassing from the middle cms of the cerebellum, before (po) and behind (j>o) the chiefpyramid bundles ; t, deeper fibres of the same set, constituting the traj)ezium ; the greymatter between the transverse fibres is not represented either in this or in the followingfigures; r, rajjhe; , superior olivary nucleus ; a. V, bundles of the ascending root ofthe fifth nerve, enclosed by a i^rolongation of the grey substance of Rolando ; VI, the sixthnerve; , its nucleus; VII, the facial nerve ; Vila, intermediate portion of thesame nerve; n. VII, its nucleus ; VIII, superior root of the auditory nerve; n. Kill,part of its outer or superior nucleus ; v, section of a vein. one or two more important collections which lie embedded in this form-ation and from wh
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