Volume 1

A manual of diseases of the nervous system / by W.R. Gowers.

Date:
1886-1888
Catalogue details

Licence: Public Domain Mark

Credit: A manual of diseases of the nervous system / by W.R. Gowers. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    the larger number of root-fibres in tbe former. Above, it also ends in a grey nucleus. Tlie function of tliis column is still unknown, although much interest attaches to it as the seat of the special central lesion in loco- motor ataxy. How far the inco-ordination of this disease depends on damage to the root-fibres that pass through the column, or to fibres that coanect the grey matter at different levels, is still unknown. We shall return to the question when discussing the disease. The direct cerebellar tract is another column of fibres which degenerate upwards. It forms a layer at the periphery of the lateral column, outside the pyramidal tract (Fig. 67), bnt does not extend through the whole length of the cord, ceasing at the level of the first lumbar nerve (Fig. 63). The anterior part of the tract (as seen in section) does not extend forwards beyond the anterior level of the lateral pyramidal tract, but, as we shall presently see, there are other fibres in fi'out of it that also degenerate upwards, and these have given rise to an erroneous opinion that the cerebellar tract extends farther forwards than it actually does. But at the level of the second cervical nei-ves, and also in the lowest part of the dorsal region, the tract lies a little anterior to its position in the rest of the cord, and hence at these places, as we have seen, the pyramidal tract comes to the surface behind the cerebellar tract, close to the posterior nerve-roots, np to which elsewhere, the cerebellar tract extends. The tract increases somewhat in size from below upwards, and hence receives fibres throughout its course, but the chief bulk of its constituent fibres enter it at the level of the lowest dorsal and first lumbar nerves, i. e. at its lowest part. These fibres come from the grey substance, coursing to it through the lateral column, along the septa that cross the pyramidal tract from the grey matter. In the latter these fibres are conspicuous objects at this level (Fig. 71), passing transversely and obliquely from the front of the posterior vesicular tract.' Into this many of them can be traced ; others change their direction and become vertical, probably passing into the vesicular tract at a different level. It is probable that the fibres come from the tract; the cerebellar tract is chiefly formed at that part of the cord at which the posterior vesicular column is chiefly developed, and the ceUs of this column have been found atrophied when the cerebellar tract is degenerated.* Besides the fibres that are gathered into the compact tract, others, belonging to its system, ascend among those of the adjacent lateral pyramidal tract. The cerebellar tract only degenerates when a lesion of the cord is at, or above, its place of origin, the junction of the dorsal and lumbar regions. If the lesion is in the lumbar enlargement, as in the case shown in Fig. 67, the tract does not degenerate. At the level of the first cervical nerve (where the pyramidal tract leaves the lateral column to cross into the anterior pyramid of the medulla) the * S.ff by Minkowski, ' Deufc. Arch. f. kl. Med.; Bd. xxxiv, p. 433. Sligl.t degene- ration of the pyramidal triicts was the only other lesion.