Notes of researches on the intimate structure of the brain : third series / by J. Lockhart Clarke, Esq.

  • Jacob Augustus Lockhart Clarke
Date:
[1861]
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Licence: Public Domain Mark

Credit: Notes of researches on the intimate structure of the brain : third series / by J. Lockhart Clarke, Esq. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    [From the Proceedings of the Royal Society, Vol. XII. N<)/57.] Notes of Researclies on the Intimate Structure of the Brain,— Third Series. By J. Lockhabt Clakke, F.R.S. Structure of the Valve of Vieussens.—The valve of Vieussens consists of four different kinds of layers. The most inferior layer is composed of epithelium, which is continuous with that of the fourth ventricle. The second layer is a stratum of longitudinal nerve-fibres, continuous with the white substance of the inferior vermiform pro- cess of the cerebellum. The third layer consists of a multitude of round, granular nuclei of about the 3500th of an inch in diameter, traversed by fibres derived from the subjacent layer. These nerve- fibres, in my preparations, may be seen in the most unequivocal manner to divide and subdivide into small branches, to which the nuclei are attached as by stalks. The fourth or uppermost layer is chiefly granular, but is also interspersed with nuclei of the same kind. Along its under side, where it joins the preceding layer, is a row of large multipolar cells, which are connected by their processes with the nuclei of both layers*. Structure of the Cerebral Convolutions.—In the human brain most of the convolutions, when properly examined, may be seen to consist of no less than eight distinct and concentric layers. This laminated structure is most marked at the end of the posterior lobe. On cutting off the rounded point of this lobe in the human brain, by a transverse section, at about the distance of an inch, measured along the side of the longitudinal fissure, I found, at this part, that the stratified appearance was very indistinct in the upper and outer convolutions, while it was still clearly observable in the inner and lower convolutions which rest on the cerebellum. It was most con- spicuous in the convolution that Hes over the bottom of the posterior notch of the cerebellum, and which runs outward and upward, and then winds inward, to reach the surface at the side of the longi- tudinal fissure. In vertical sections of convolutions taken from the end of the posterior lobe, where the laminated structure is most marked, the * This description of the valve of Vieussens formed part of the manuscript of a Paper published in the ' Proceedings of the Royal Society' for June 20, 1861, but was accidentally omitted in the printing.