1890.] On the Central Motor Innervation of the Larynx. 341 



XII. "An Experimental Investigation of the Central Motor 

 Innervation of the Larynx. Part I. Excitation Experi- 

 ments." By FELIX 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, 1890. 



(Abstract.) 



In this paper the authors communicate the first part of a series of 

 researches in which they have been engaged from time to time since 

 1886, on the nature of the representation of the intrinsic laryngeal 

 movements in the central nervous system. 



Briefly stated, the anatomical arrangement of the laryngeal nerve 

 centres they believe to be as follows : 



a. Cortical areas of representation. 



b. Connecting fibres in the corona radiata and the internal 



capsule. 



c. Bulbar areas of representation. 



So also the physiological differentiation existing in the functional 

 activity of these centres and fibres they regard as to be viewed from 

 two standpoints 



1. The phonatory laryngeal movements. 



2. The respiratory laryngeal movements. 



Of these the former are shown to be especially represented in the 

 cortex, and the latter more particularly in the bulb. 



After a complete historical resume of the experimental, and also 

 clinical, work already done on the subject, the authors describe and 

 discuss the experimental procedure adopted by them, with especial 

 reference to the complications introduced in the employment of 

 varying intensity of stimulation, depth of anaesthesia, species, indi- 

 vidual peculiarities, and age of the animal. 



The results are then arranged in order, according to the part 

 stimulated, beginning with the cortex cerebri and ending with the 

 bulb. 



It is shown that in the cortex cerebri there is represented the 

 phonatory movement of adduction,* and that this is more completely 

 developed, the higher the animal is in the scale of evolution. 



Further, that in the neighbouring regions of the cortex the respi- 

 ratory movements of the larynx, acceleration, intensification, and 

 slowing, are also represented. Only in one kind of animal, viz., the 

 cat, were a focus and area of pure cortical representation of abduction 



* Discovered by Ferrier and accurately localised in the dog by Krause. 



