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Vin. An Experimental Investigation of the Central Motor Innervation of the Larynx. 
By Feltx Semon, M.D., F.R.C.P., and Victor Horsley, B.S., F.R.S. 
[From the Laboratory of the Brown Institution.) 
Received. June 17,—Read June 19, 1890. 
[Plates 31, 32.] 
Part I.— Excitation-experiments. 
a. Introduction. 
In the course of observations dealing with the physiology of the motor innervation of 
the larynx, the results of which were embodied in a paper recently presented by one 
of us (F. S.) to the Royal Society,* it was shown that the central innervation of the 
larynx played a much more important role in the function of respiration than had 
previously been accorded to it. More especially it was shown that certain nerve- 
centres were constantly at work in maintaining a reflex-tonus of the abductor muscles 
(posterior crico-arytsenoids) indispensable for the mechanism of quiet respiration in 
Man. 
In 1880, 1881 and 1883t it had been shown by one of ns (F. S.) that these same 
muscles (the abductors) were more liable to degenerative changes in cases of organic 
disease of the motor nerves of the larynx from the medulla oblongata downwards, and at 
the same time that functional disorders of the laryngeal motor apparatus almost exclu¬ 
sively affected their antagonists, the adductors. The explanation of all these different 
phenomena presented great difficulties, and, although light was thrown upon them in 
very various and unlooked-for ways, it soon became evident that neither clinical and 
pathological observations in Man alone, Jior experiments upon the peripheral nerve- 
mechanism of animals, would suffice to solve all the questions here involved. 
Now, the fact just mentioned—viz., that in functional disorders [e.g., hysterical 
aphonia) those motor laryngeal nerve-fibres only which subserve the volitionary func¬ 
tion of the larynx [i.e., phonation) ordinarily suffer, whilst, on the other hand, in 
* “ On the Position of the Vocal Cords in Quiet Respiration in Man, and on the Reflex-tonus of their 
Abductor Muscles.” ‘Roy. Soc. Proc.,’ 1890 (vol. 48, p. 403). 
t (a) Foot note in German Edition of Morell Mackenzie’s ‘ Diseases of the Throat and Nose,’ vol. 1, 
p. 574. 
(5) ‘ Archives of Laryngology,’July, 1881 
(c) ‘Berliner Kliuische Wochenschrift,’ No. 46, et seq., 1883, 
2 R 2 
12.12.90 
