Investigations into the segmental representation of movements in the lumbar region of the mammalian spinal cord : excitation of the spinal cord, and direct excitation of the spinal nerve roots / by W. Page May ; [communicated by Victor Horsley].

  • May, W. Page (William Page), 1863-1910.
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: Investigations into the segmental representation of movements in the lumbar region of the mammalian spinal cord : excitation of the spinal cord, and direct excitation of the spinal nerve roots / by W. Page May ; [communicated by Victor Horsley]. 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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    to maintain the circulation in tlie cord, a cataract knife was later passed under the dorsal vessels, and then by cutting forwards the cord was left with as good 'a circulation as possible. This method answered very well. The only result observed to follow such separation of the cord from the brain, upon the movement elicited as above described, was one of increased excitability. The limits described (p. 196) (areas of vertical extent) Avere found to prevail precisely, and the cord was excitable, quite up to the level of the section, a smaller stimulus being necessary to produce the same movements as before. For instance, the distance of the secondary from the primary coil before section of the cord being 30 millims. for an adequate stimulus, the same result was obtained after division of the cord-Avith secondary coil 50 millims. or 60 millims. from the primary. As regards the above- described influence of section, other conditions, as is well known, exerted an obvious effect. Thus, for instance, increasing the narcosis diminished the excitability, or even removed it; and, on the other hand, repeated stimulation either of the cord or the posterior nerve roots (see below) increased the excitability. Further, if the cord were not irrigated from time to time with saline solution or other suitable agent, but allowed to dry, then for a time its excitability was increased. Again, the application of the red-hot needles described above gave rise to an increase of excitability. - As far as was compatible Avith the performance of the foregoing experiments, the knee-jerks were investigated, and it was found, of course, that with the cord intact they were present, but Avere influenced by the conditions which increased or diminished the excitability of the cord. When the cord was cut through in the dorsal region, and it was perfectly obvious from the gap of half-an-inch or more between the tAvo portions that no direct communication could exist between the two parts (and therefore betAveen the lumbar region and the brain), the knee-jerks, nevertheless, persisted in nearly every instance (in some thirty animals), and were much more active and more readily elicited than before the section of the cord. Sometimes soon after section the knee-jerks could not be elicited, but by waiting a few minutes to allow the shock to diminish or pass aAvay they could almost invariably be obtained, and that in a more active condition than before the section. These observations, it will be remembered, were made on the dog alone.