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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    that in the upper part of the dorsal region (compare with fig. G, Plate XXL). This tract is traversed by several roots of the spinal-accessory nerve, in their course forwards to the anterior cornu, and contributes, with the edge of the posterior cornu, to form a beautiful network (N, N, N) in the lateral column, through which the nerve enters. Its cells are triangular, oral, and fusiform in different directions: some of them are elongated in the dii-ection of the transverse commissure and towards the front of the posterior vesicular column; others extend outwards with radiating fibres through fissures of the lateral column. There is reason, therefore, to believe that this tract forms a part of the tractns intermedio-lateralis. In the Sheep and Ox, and probably in all Mammalia, a ])ec\iliar group of ceils, which is traversed by the roots of the spinal-accessory nerve, is found in the same situation; and this group, in ascending the medulla oblongata, retires inwards to the space behind the canal, and there contributes to form the nucleus which gives origin to the highest roots of the nerve. It has also been seen that the cells of the tractus intermedio-lateralis are elongated with their processes in a longitudinal direction, and reached by both the posterior and anterior roots of the spinal nerves, and perhaps by the spinal-accessory; that the latter nerve extends forwards to the cells of the anterior cormi^ wdiich also send some of their processes longitudinally, and are reached by the postenor roots. Moreover, I have in another memoir shown that, while one portion of the upper roots of the spinal-accessory nerve and one portion of the vagus roots proceed inwards to their respective nuelei behind the canal, other portions of both bend forwards to the vesicular network into which the anterior cornu has become resolved*. Again, I have shown, in the same memoir, that some of the roots of the trifacial nerve descend longi- tudinally through the caput cornu, between the transverse roots of the vagus; in which course they are probably brought into connexion with the respiratory centres, and perhaps also, like the vagus, with the anterior grey substance of the medulla. These extensive and intimate connexions seem to afford an explanation of the mechanism by whicli impressions made on the vagus and on the incident fibres of the trifacial and spinal nerA cs, may call into action the whole class of respiratory muscles; and if the tract which I haA e just described in the upper part of the cervical region be continuous, as it probably is, Avith the tractus intermedio-lateralis, which is reached by the dorsal nerves supplying the intercostal and other respiratory muscles of the trunk, the explanation in question Avil] be still more completef. I shall noAV briefly trace the posterior vesicular columns of the human cord from the dorsal region doAvnAvards. At the upper part of the lumbar region, as in Mammalia, they are larger than in any other portion of the cord (see fig. 13, M, Plate XXL ). They have the same form and dark appearance as in the dorsal region, but contain moie large cells. As they descend, hoAvever, the dark masses diminish, and are frequently broken into * See tlie author’s “ Medulla Oblongata,” Phil. Traus. Part I. 18-38, pp. 232, 233, tigs. 19 and 39. t Both in this communication and that on the Medulla Oblongata, I have abstained from drawing any physiological conclusions, except on this one occasion, where so many d'pferent facts required to be brought together while fresh in the memory of the reader.