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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    (b.) Kind of Movement Obtained from the Res^jcctive Roots. The most striking result, however, among these general considerations was the difference in effect obtained by excitation with the same stimulus, and under precisely the same conditions, and within a few seconds of each other, of the periphei'al end of the anterior and the central end of the posterior root respectively. It was then found that, whereas stimulation of the central end of the posterior root gave flexion of the whole limb, excitation of the peripheral end of the corre- sponding anterior root gave extension of the whole limb. Of course throughout these experiments there has been no excitation of the cerebral end of the anterior root, except when the nerve was stimulated in continuity. Besides the fact that the whole doctrine of recurrent sensibility, as originally formulated by Ma.iendie, Bernard, and others, does not find much support at the present time, there is also the direct experimental evidence of Gotch and Horsley to show that stimulation of the cerebral end of the anterior root has no appreciable physiological effect on either the centres or channels in the spinal cord (‘Phil. Trans.,’ B, 1891), for these observers found that, whereas excitation of the central end of the posterior root gave maximal evidences of change in the electrical state of the spinal cord, on the other hand excitation of the central end of the anterior root not only produced no effect in the state of the spinal cord, but even stimulation of the central end of the whole of the anterior foots represented in the sciatic nerve gave, when the corresponding jjosterior roots were cut, no resulting change in the spinal cord whatever. This remarkable functional distinction between the roots (viz., anterior, extension ; posterior, flexion) was quite constant, and was obtained in every animal in which the expei’iment was made. Of course the movement which took place w’as a resultant effect, and was produced by the contraction of many muscles, each of which was con- cerned in producing either the flexion or extension of a particular joint, in one case acting with a combination of muscles when flexion resulted, and in the other case with another set of muscles when extension resulted. Hence stimulation of either of the anterior 5th, 6th, or 7th lumbar roots produces extension, and similarly that of the corresponding posterior roots flexion. So that in a sense the anterior and posterior roots appear to be antagonistic to one another in their action. Further, with spinal cord and nerves intact, stimulation of a posterior root (say the 5th) produces flexion of a joint, ev'^en when all the neighbouring anterior roots are divided. Hence this effect can only be due to the stimulus passing from the posterior root through the spinal cord along a particular anterior root to the muscles (differentiation of function in the nerve centres of that root), yet stimulation of this same anterior root produces extension. And this agrees entirely with the results obtained in a different way by Dr. Bisten B.USSELL (‘Phil. Trans.,’ B, 1893). The above experiment also goes to show that stimulation of one posterior root causes impulses to pass out along many anterior roots.