. The Journal of comparative neurology and psychology. the same level. In thesection through the left half of the brain (Fig. 21) the cerebellarportion was broken away as indicated by the dotted line; in the righthand section (Fig. 22) the reticular formation was broken as indi-cated by the dotted line, but neither of these breaks in any wayaffected the structures under consideration. An examination of thefigures will show that the chief relations here are identical Avith thosein the earlier foetus. Medullation is now much more general. Thereticular formation contains many medullated fibers an
. The Journal of comparative neurology and psychology. the same level. In thesection through the left half of the brain (Fig. 21) the cerebellarportion was broken away as indicated by the dotted line; in the righthand section (Fig. 22) the reticular formation was broken as indi-cated by the dotted line, but neither of these breaks in any wayaffected the structures under consideration. An examination of thefigures will show that the chief relations here are identical Avith thosein the earlier foetus. Medullation is now much more general. Thereticular formation contains many medullated fibers and the pons,acustic area and cerebellum show fairly numerous fibers. Thesensory root is cut just at the point where a part of its fibers areturning into the spinal trigeminal tract, which is better formed on Johnston, The Radix Mesencephalica Trigemini. 625 the right (Fig. 22), since that section is somewhat further caudalthan the left-hand one. Many fibers of the sensory root enter thechief sensory nucleus and the cephalic end of the substantia gela-. V Fig. 21. Human foetus, 42 cm. Transverse section through the trigeminalroots on the left side. The short heavy line at the left below is the outersurface of the pons, x, x, x indicate the ends of the motor bundles, where theyleave the section. All the fibers below and to the left from these are tinosa. In each section is seen a large bundle of sensory fibers pass-ing dorsad over the outer surface of the sensory nucleus. A part ofthe fibers enter that nucleus, the remainder seem to pass on to thecerebellum. 626 Journal of Comparative Neurology and Psychology. The motor nucleus is indicated in Fig. 21 by a dotted line and inFig. 22 by the line along which the section was broken. Its dorso-lateral surface is covered, as in the younger specimen, by bundles ofthe motor root. On each side there is a broad but loose bundle ofdecussating fibers and beneath this are denser bundles of fibers arising Vmes. I flj V,
Size: 1472px × 1698px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwistarinstituteofanat, bookcentury1900, bookdecade1900
