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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    (see F, Plate XX. tig. 4; Plate XXI. fig. 3). Transversely its outermost or marginal vesicles lie, for the most part, with their longer axes and processes in an mitero-])Osterior direc- tion, as in fig. 2, Plate XX.; while those more internal are elongated in the direction of the transverse commissure, with the fibres of Avhich, as already stated, their processes are continuous. As it ascends, however, through the cervical enlargement, it gradually disappears; but, as in the dorsal region, the lateral portion of the grey substance is still traversed, from behind forwards, by numerous fibres apparently in connexion with branched and with very elongated cells of all sizes, amongst which are scattered a few that resemble those of the tractus intermedio-IateraUs. Through this lateral portion of the grey substance the lowest roots of the spinal-accessory nerve hewCi forwards to the cells of the anterior cornu. In the region of the upper cervical nerves, there reappears a vesicular tract in the same ])osition as the tractus intei'medio-lateralis, and composed of the same kind of cells, which are elongated in a lateral direction and send their processes, on the one hand, outwards through the lateral column, and on the other, inwards to join the fibres of the transverse commissure behind the central canal (see F, fig. 11, Plate XXI.; and fig. 12, Plate XXV.). It is traversed by the roots of the spinal-accessory nerve (r) as they bend forwards on their way to the anterior cornu. In descending the cord from the dorsal to the luinhar region, the posterior grey sub- stance undergoes a series of changes nearly similar to those which are observed in ascend- ing to the cervical enlargement. The posterior cornua become gradually more separate, or thrown aside from each other, in a direction obliquely backwards. At the upper })art of the lumbar enlargement, the posterior vesicular columns are decidedly larger than in any other region of the cord (M, fig. 13, Plate XXL). In a transverse section each presents the appearance of a dark oval mass, lying along the whole inner half of the cervix cornu, the border of which it renders convex against the deep strata of the posterior column. Its larger cells are more numerous than in the dorsal region. They do not form in the centre of the column a circumscribed group, but lie scattered irregu- larly through the whole inner half of the cervix, which their processes traverse in differ- ent directions and envelope in different planes. Many of tlie oval variety are elongated in the direction of the cornu, and their processes are continuous, on the one hand, with the transverse commissure, and on the other, with the ])osterior roots of the nerves. Some stretch along the convex border of the cervix; and sometimes a crescentic or trian- gular cell, in the same situation, sends one of its processes througli the posterior column with a bundle of radiating fibres. Part of the fibres of the transverse commissure run out in front of the mass, as already stated, in company with processes or fibres which proceed from its inner side; of these some are continuous with the cells of the tractus intermedio-lateralis, while others escape through the lateral column. The tractus intermedio-lateralis is prominent at the border of the grey substance, between the anterior and posterior cornua, but its cells are not so numerous as in the upper dorsal region.