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

  • Semon, Sir Felix, (1849-1921)
Date:
1890
Catalogue details

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.

    14/32 (page 198)
    of course, possess considerable interest. From anatomical reasons these resolve them- selves under two headings— (1) Upward Movement of the Larynx, (2) Downward ,, „ ,, (1) Upivard movement of the larynx we noted to occur only in front of the Fissure of Rolando, between it and the small secondary sulcus marked v in figure. This movement is associated with swallowing and mastication, these actions being (Beevor and Horsley) represented in the strip of cortex thus indicated. Clearly, in this association, we have only the completion of the observed representation of these complicated acts. (2) Downward movement of the larynx we obtained by exciting the cortex just behind the Fissure of Rolando between that sulcus and a line parallel to it, drawn from the lower end of the intraparietal sulcus to the Fissure of Sylvius. Once we observed confusion between the movement of the larynx upwards and downwards to occur at this point, the downward direction predominating. Epilepsy.—We have frequently observed epilepsy to follow excitation of the cortex in this region. At the commencement of the fit, the vocal cords are strongly adducted, often with tremors, i.e., confusion between adduction and respiratory (?) abduction, this persisting during the tonic stage. Then, in the subsequent clonic stage, the movement of adduction alone occurs as single spasms and ceases, of course, often suddenly. Carnivora. —Dog. Phonation.—The following account applies only to the adult animal; we shall speak later of the differences which are caused in the cortical representation according to the age of the individual examined. The nomenclature of the sulci employed will be that given by Langley in his admirable paper on this subject,” except that for brevity we shall speak of the anterior limb of the sigmoid gyrus as the prsecrucial gyrus, and similarly of the posterior limb as the postcrucial gyrus. In the original description given by Krause! of the cortical representation of the movements of the vocal cords, that author localised the focus of the representation to be situated in the prsecrucial gyrus [or, as he called it, following Munk, the gyrus prsefrontalis (Owen),] just where that gyrus terminates below in a narrow pillar or isthmus connecting it with the anterior composite gyrus. At this point he found that excitation, as a rule, produced bilateral adduction of the cords ; this we have completely confirmed, but we have also found that while the spot indicated is a focus, nevertheless slight adduction can be obtained by excitation of the whole of the lower two-thirds of the prsecrucial gyrus, and also a few millimetres of the upper extremity of the anterior composite gyrus. * ‘ Journal of Physiology,’ December, 1883, p. 248. f ■ Archiv f. Anatomic und Physiologic, Phys. Abth.,’ 1884, p. 203.