. A manual of diseases of the nervous system. and gelatinous. The latter forms acap on the posterior horn, and a layer immediately around the centralcanal, and is named on account of its naked-eye aspect. It consistslargely of neuroglia, traversed, however, by nerve-fibres, and withnumerous nerve-cells scattered through it. The spongy substance,which forms the rest of the two cornua, consists mainly of an exces-sively fine f elty network of very narrow meduUated nerve-fibres, nakedaxis-cylinders, and fine nerve-fibrillse which arise, in part at least,from the dendrites of the nerve-cells, and
. A manual of diseases of the nervous system. and gelatinous. The latter forms acap on the posterior horn, and a layer immediately around the centralcanal, and is named on account of its naked-eye aspect. It consistslargely of neuroglia, traversed, however, by nerve-fibres, and withnumerous nerve-cells scattered through it. The spongy substance,which forms the rest of the two cornua, consists mainly of an exces-sively fine f elty network of very narrow meduUated nerve-fibres, nakedaxis-cylinders, and fine nerve-fibrillse which arise, in part at least,from the dendrites of the nerve-cells, and in part by a division ofthe axis-cylinders of the nerve-fibres. These structures are em-bedded in a supporting neuroglia. Through it course many largermedullated nerve-fibres, passing to or from the white columns andnerve-roots. In it also lie many nerve-cells of various sizes. Thosein the anterior cornu are, for the most part, large ganglion-cells ; each contains a large nucleus, and usually a mass of pigment, and Fig. 67. Fia. 68. Fia. Fig-. 67.—A nerve-cell from tlie anterior cornu of thespinal cord of man: a, uubranched process becomingthe axis-cylinder of a nerve-fibre; b, pigment mass.(After Gerlach.) Fig-. 68.—Nerve-cells of the anterior cornu sending a pro-cess into tl e anterior root. (After Henle.) Fig. 69.—A fine nerve-fihre dividiiii into two parts, eachof whiih joins the plexus of fibrillse formed by thebranching processes of a nerve-cell. From the spinal cord of au ) (After 204 SPINAL CORD. sends out several processes. One process, the axon, is continuouswith the axis-cylinder of a nerve-fibre (Fig. &?), and can be sometimestraced into a fibre of an anterior root (Fig. 68). The other processes,or dendrons, after a longer or shorter course divide and subdivide,their ramifications ending in minute knobs in the sponge-like matrixof the grey substance. In this they are probably brought into closecontiguity with the terminal ramifications of other
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectnervoussystemdisease
