. The anatomy of the central nervous system of man and of vertebrates in general. Neuroanatomy; Central Nervous System. 80 ANATOMY OF THE CENTRAL NERVOUS SYSTEM. therefore, with some hesitation that I designate this structure as the "nucleus of the posterior ; But the greatest difference between this section and one of a typical spinal cord is the fact that in the space between anterior and posterior horns innumerable commissural cells have made their appearance, cells whose large neuraxons, arranged in small fasciculi, pass upward through the medulla even into the Mesencepha
. The anatomy of the central nervous system of man and of vertebrates in general. Neuroanatomy; Central Nervous System. 80 ANATOMY OF THE CENTRAL NERVOUS SYSTEM. therefore, with some hesitation that I designate this structure as the "nucleus of the posterior ; But the greatest difference between this section and one of a typical spinal cord is the fact that in the space between anterior and posterior horns innumerable commissural cells have made their appearance, cells whose large neuraxons, arranged in small fasciculi, pass upward through the medulla even into the Mesencephalon and Thalamencephalon. This is prob- ably a great system of association-fibers which connect certain levels of the cranial segment of the central system to each other and with the anterior end of the spinal cord. This system, which is similarly located in all ani- mals, is characteristic of the Medulla, and is well adapted to be the organ. Fig. 41.—Section through the medulla oblongata of a Kay: the Ceplialoptera lumpus. of those most intimately co-ordinated functions whose seat is in the Medulla. In the figure this region is designated as Tradus hrevis. Without doubt we have to deal here with an increase of that structure already described with the spinal cord as the cellulge commissurales and the tracts arising from them. As in the spinal cord, so here there exist fibers of short course, crossed and uncrossed. The ventral commissure, small in the spinal cord, naturally becomes much increased incident to the increase of the whole system. It is known from this point up to the Corpora Quad- rigemina as the i'apM decussation. Within this decussation, as in the spinal cord, are cross-fibers of other categories than those which arise from the cellulge commissurales. But these will be described later. The area of association-fibers—, the Tr. brevis of the oblongata—is just as well developed in the lowest vertebrates as in the highest representa-. Please note that these
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