Further researches on the grey substance of the spinal cord / by J. Lockhart Clarke.

  • Jacob Augustus Lockhart Clarke
Date:
1859
Catalogue details

Licence: Public Domain Mark

Credit: Further researches on the grey substance of the spinal cord / by J. Lockhart Clarke. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    and lumbar enlargements they are joined only by a narrow band of the transverse com- missure, immediately behind the canal. During these changes, the i)osterior vesicular columns undergo certain modifications in form, size, and structure. As they approach the cervical enlargement, the cylinder or opake portion of each is gradually reduced in size, but the whole inner half of the cervix is still occupied by the surrounding layer of cells. Sometimes the cylinder is intersected, and dhided into smaller portions, by fibres of the transverse commissure, in continuity Avith the processes of some of its OAvn cells, which are more or less intermixed with those of the suiTounding layer; other fibres of the transverse commissure, in their passage outwards, enclose it in front and behind, and after partly reuniting on its outer side and running backwards through the caput cornu, whei'e they are also continuous with cells, they diverge and traverse the gelatinous sub- stance as posterior roots of the nerves. Some of those fibres Avhich enclose it in front, in company Avith processes or fibres from the inner side of the A^esicular column, proceed, as already stated, AA'ith a gentle cun'e, or in a slightly serpentine course, to the lateral border of the grey substance, where they are partly continuous Avith the cells of the fractus intermedio-lateralis (F, figs. 2 & 4, Plate XX.), Avhile the rest escape through the lateral column. Behind, and at the sides of, the canal, the fibres of the transverse commissure are connected Avith many small oval and fusiform cells,—sometimes Avith others of larger size,—and are separated at intervals by blood-vessels Avhich run longitu- dinally and obliquely and communicate Avith one of considerable size, Avhich proceeds transversely, Avith the commissure, to the lateral grey substance, Avhere it diA’ides into numerous branches. In the middle of the ceiwical enlargement, the circumscribed cylinder of the posterior vesicular column has entirely disappeared, but the Avhole inner half of the cervix cornu is filled Avith cells, and contains a someAvhat dark and imper- fectly-defined mass, Avhich is traversed by the fibres of the transverse commissure and interlaced by the posterior roots. In the Ox many of these cells are very much branched, and send out their processes in all directions; some are fusiform in various degrees ; others are apparently riband-shaped, and sometimes not much broader than the processes into Avhich they gradually taper. In the upper part of the cervical region, near the origin of the third pair of iierA cs, a darker and more defined mass (M, fig. 12, Plate XXV.) reappears at the base of tlie cervix cornu. It is composed of cells both large and small, and of bundles of tin' posterior roots which interlace amongst them. This mass is not distinctly circum- scribed like that of the posterior A'esicular column in the dorsal region, but is some- what triangular, with one of its angles directed toAvards the point of the posterior cornu, another towards the transverse commissure, and the third obliquely foiAvards and out- Avards toAvards the antero-lateral column. It gradually diminishes upAA^ards, and disap- ])ears near the first pair of nerves. The tractus intermedio-lateraUs is larger at the upper part than in the middle of the dorsal region. On the one hand it projects further into the lateral column, and on the other tapers inAvards across the grey substance to near the front of the vesicular cylinder 3x2