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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    . From this it will be seen that the various areas in the postero-external column, the stimulation of which on the surface of the cord produces movements in the limbs, anus, perineum, and tail, all overlap one another, but that, on the whole, the hip area is a little nearer the cerebrum than that for the toes, and the area for the knee more proximal than that for the foot, and so on; but the whole representation of the joints is so brought together within the narrow space of the lumbar enlargement that no sharp division of the points of maximal representation is possible. This much ascertained, it was necessary to still further differentiate the foci of representation of the movements resulting from direct stimulation of the cord by a control experi- ment. „ For this purpose Professor Gad suggested the application of a fine hot needle transversely to the path to be divided, and by this means it was quite easy to cut any particular strand of fibres without pressing on surrounding points and without causing hasmorrhage of any kind. For instance, in a dog under ether and conditions as described above application of the electrodes to the postero-external column at any point of the 4th or 6th lumbar segment produced flexion of the hip and knee, and these movements seemed identical in every respect; then by gentle application of the red-hot needle the postero-external column was divided across in the centre of the 5th segment, after which stimulation of the 4th segment only evoked flexion of the hip, whereas stimulation of the 6th segment produced only flexion of the knee. This fact is of great interest, especially in relation with the observations of Pamon-y- Cajal and Barbacci, because it is so plain that movement which results from stimulation of the posterior external column must be brought about not only by means of stimulation of the short reflex arc fibres in the same segment, but also by means of stimulation of the intersegraental (see also below) fibres (Pamon-y-Cajal), and in all probability by stimulation either directly or indirectly of the collateral fibres as well. (d.) Effect of transversely dividing the Cord above the Lumbar Enlargement. It was expected, and not without reason, as the experiments detailed show, that in excitation of the uninjured spinal cord the influence of the higher (cerebral) centres could be readily and adequately abolished by the employment of ether narcosis. To render, however, the conditions more absolute tov/ards tbe end of the experiment, a complete transverse section of the cord was made at a variable distance, usually from two to six segments above the part investigated, and the excitation repeated. For this purpose the animal was placed under deeper narcosis by ether, so as to diminish shock as much as possible, and then the cord and vessels were completely divided by a sharp cataract knife, the two parts of the cord retracting so that a gap of at least 6 millims. to 10 millims. resulted. The hsemorrhage was usually sharp, but, by the application of a little amadou to the bleeding points, it almost immediately ceased and gave no further trouble. With a view to diminish the hsemorrhage and