An experimental investigation of the central motor innervation of the larynx / by Felix Semon and Victor Horsley.

  • Semon, Sir Felix, (1849-1921)
Date:
1890
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Licence: Public Domain Mark

Credit: An experimental investigation of the central motor innervation of the larynx / by Felix Semon and 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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    This representation of the intrinsic movements of the larynx is not pure except very special care be taken to adjust the strength of the excitation sufficiently to prove a minimal stimulus to the point excited. As a rule, it is accompanied by movements of the tongue and of the pharynx, e.g., swallowing.Occasionally, however, we have obtained movements of the vocal cords without any concomitant action elsewhere. We have never, in the adult Dog, witnessed abduction, although we have explored the whole of the frontal lobe on its orbital and external nasal surfaces completely. Respiration.—We now proceed to remark upon the representation of respiratory movements of the larynx also to be found in the cortex of the adult Dog. We have found that the following conditions may be produced with absolute certainty. a. Acceleration of Respiratory Movements of the Vocal Cords.—This is chiefly represented just above the focus for the movements of the adduction of the cords, i.e., just in the middle of the lower third of the prsecrucial gyrus, but excitation of the whole of the prsecrucial gyrus as a rule produces this effect in diminishing degree, as we move from the focal point just mentioned. In the performance of this act the abduction of the vocal cords is, as a rule, diminished in extent, as has already been mentioned in speaking of their phonatory representation in the same area, but they otherwise present the ordinary alternate rhythm of abduction and adduction. Before passing to the next point observed we must here make a few remarks upon this extraordinary result, because it has not been, so far as we know, described in connexion with any function other than the respiratory. Quickening of respiration has very properly been termed by BiCHETt polypncea, and has been proved by him to be the means whereby the thermo-taxic apparatus restores the equilibrium of the body by providing for extra loss or dissipation of heat. Further, work of a memorable kind has been done upon this subject by Ott,J who has directed special attention to this point, and has produced by excitation the same acceleration of respiration, but from excitation of the internal capsule. (Vide our remarks on the internal capsule.) We provisionally quite agree with the conclusions and explanations offered by these writers, and we would here remark, that so far as we can see, the results obtained by Christiani,§ and probably those by Martin and Booker,|| are to be explained as the results of excitation of the fibres leading down from this very extensive and cortical representation of the respiratory acceleration * [While this paper was passing through the press Monk published, in the 2nd edition of his ‘ Gesammelte Mittheilungen uber die Functionen der Grosshirnrinde,’ a statement on p. 178 to the effect that we have confounded the focal representation of phonatiou with laryngeal movements when accom- panied by associated movements of the mouth, pharynx, &c. The justice of this statement we leave to the opinion of our readers.—August, 1890.] f ‘ La Chaleur Animale.’ X ‘ Laboratory Researches,’ Easton, Pa. § ‘ Zur Physiologic des Geliirnes.’ Berlin, 1885. || ‘ Journal of Physiology,’ vol. 1, 1881.