On the restoration of co-ordinated movements after nerve-crossing, with interchange of function of the cerebral cortical centres / by Robert Kennedy.

  • Kennedy, Robert, -1924.
Date:
1901
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Licence: In copyright

Credit: On the restoration of co-ordinated movements after nerve-crossing, with interchange of function of the cerebral cortical centres / by Robert Kennedy. 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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    for the nervous impulses, or, on the other hand, the phenomenon might he due to the estahHshment of new paths due to the inevitable imperfect coaptation of the divided nerve ends. Each of the nerve-fibres in a nerve-trunk is supposed to be the path of commimication between a central cell and a definite peripheral area. On dividing the nerve-trunk, and reuniting it by suture, it seems to be a difiiculty to assume that perfect coaptation has been made of all or even of a majority of the cut fibres. If such an assumption is made, then the difiiculty of the problem disajDpears, but it is clear that an assumption of the kind is unjustifiable. In a former jDaper (20)* I showed from experiments on the sciatic nerve in dogs that the progress of recovery is practically the same whether the nerve is reunited by suture as accurately in the old position as possible, or whether the opposite state of matters is ensured by rotating the peripheral segment through a semicircle before reuniting it to the central segment. It is true that the peripheral segment of the nerve undergoes Wallerian degeneration after the act of division, but it is never- theless still a necessity for the regeneration of the nerve. Taking the view of regeneration advocated by Ranvier (8, 9), it is a necessity only as a guide for the growth of the young sprouting nerve-fibres to the peripheral terminations, supplying these fibres at most with their envelopes (Strcebe, Notthaft, Howell and Huber). Taking, on the other hand, the view that the peripheral segment regenerates its own young nerve-fibres after the degeneration of the old fibres, which view I prefer (15), then each fibre in the peripheral segment is reproduced from the point of division on to the peripheral ending. In either case careful coaptation of the cut ends of the nerve would seem to be an important element for the re-establishment of the old paths along which nervous impulses were transmitted. If accurate coaptation is impossible, and if the accuracy of coaptation is not an essential condition of restoration of co- ordinated movements, then the explanation of restoration is either that the central ends are endowed with the cajDacity of finding their proper peripheral ends, or that the nerve-centres are capable of altering their functions in so far that, when brought into connection with new muscular fibres by the alteration of the paths for nervous impulses, they can call forth muscular contractions in the new muscular fibres, so as to cause perfectly co-ordinated movements. It was thought, when my former experiments were made, that the microscopic appearances of the segment of reunion would decide whether the restoration of function was due to the re-establishment of the old paths or to the formation of new paths. On examination, however, this jDoint was not clearly indicated, as the segment of reunion presented the appearance of a neuroma, the nerve-fibres being greatly convoluted. I therefore conducted several experiments on nerve-crossing, or the division of neighbouring nerves and cross union, in order to determine whether, with absolutely secured alteration of innervation, restoration of voluntary co-ordinated movements could occur. * The numbers in parentheses refer to the Bibliography, p. 160.
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