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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    Repeatedly it was found that with a minimal stimulus it was possible to evoke movement either in the tail (and anus) only, or in the hamstrings, or in the hip, or in the side only, and whenever this was obtained, it was an invariable rule that the point for producing movement in the tail was placed in the cord mesially of that point stimulation of which gave movement in the hamstrings, and that this latter point was mesial of that for the hip, while most external of all was the point from which movement of the side of the trunk was elicited. Of course, if the strength of the stimulus were increased, then the current spread, and stimulating neighbouring points of excitability produced concurrent movement in two or more of above- mentioned parts, such as tail and knee. This lateral arrangement has been in pjart foreshado^^•ed by the observations of Mott on the relation between the coccygeal nerves and Goll’s column. The movements resulting from excitation of a segment of the spinal cord in the lurnbo-sacral region and those from excitation of the corresponding posterior root are similar, but are never quite identical. In each case flexion is the predominant effect, but in the former case the resulting movements are always stronger than in the latter, and frequently movements in other parts (tail, perineum, &c.) are added. This ditference is to be expected, because, of course, in excitation of the postero-external column branches and fibres (ascending, descending, and collateral) many posterior roots are stimulated. Investigation into the Segmental Representation of the Cord by Comparison OF THE Results of Excitation of the Anterior and Posterior Roots. On pp. 199 and 201 is already given in tabular form the results obtained by different observers who have investigated this subject by stimulating the anterior roots. The prevailing notion concerning the physiological function of representation of movement in the spinal cord is certainly that the fibres along which the stimulus passes when the posterior roots are excited, are short arc fibres, i.e., limited horizontally to the segment they enter. This simple view, however, is not borne out by the results of my experiments, as will be seen by the following account. It was soon found that thei’e were two sets of facts giving evidence of a different kind which showed (1) that the arrangement of the centres and their afferent fibres was more complex, and (2) that some change could be brought about within the centres by stimulation of the posterior roots which affected the excitability of the anterior roots. (a.) Character of Movement Elicited from the Respective Roots. There is a marked difference in the kind of contraction of the muscle, that from the anterior root being sha)‘p, and that from the posterior root being more slowly developed.