OF THE CENTRAL MOTOR INNERVATION OP THE LARYNX. 
197 
different type in the larynx and general respiration, e.fj., closure of the riina 
glottidis with general acceleration of respiration. We shall therefore proceed at 
once to describe the laryngeal efiects only, and shall reserve what we may wish to 
state relating to the effects produced on general respiration for another communication. 
In arranging our results we divide them as indicated on p. 188, i.e., first, according to 
the species of animal employed, and we shall commence with the highest order. 
Monliey. 
Species employed .—We have explored the cortex in examples of Macacus sinicus, 
Macacus rhesus, and Macacus cynomolgus. 
Among these Macacus sinicus afforded the best results. The general conclusions 
we derive from our excitation experiments are as follows :— 
Intrinsic Laryngeal Movements.~I\\at in the foot of the ascending frontal gyrus, 
just behind the lower end of the pra3central sulcus {vide Plate 31, fig. 1),* there is a 
focus of rej^resentation of the movements of the vocal cords which are independent of 
movements of the pharynx, when the most anterior part of the focal area of 
representation is excited. 
This focus is limited anteriorly by tlie prascrucial sulcus {p.c., fig. 1) and a line 
continuing the direction of that sulcus to the Fissure of Sylvius, superiorly, by a 
line drawn horizontally (parallel to Fissure of Sylvius) through the upper extremity 
of the small secondary sulcus marked v, see fig. 1, interiorly, by the Fissure of 
Sylvius, and posteriorly, by the sulcus v. 
The purely intrinsic movement of adduction of the vocal cords seems to be 
represented in the front half (marked darkly F, in fig. 1) of this focal area. In the 
posterior half, i.e., just in front of v, it is accompanied by pharyngeal movements 
especially. (Beevob and Horsley.) 
In this focal area the character of the movement represented is invariably adduc¬ 
tion (Monkey), and not only complete, but also perfectly bilateral. We have never 
observed abduction to follow excitation. Outside the focal area the intrinsic move¬ 
ments are also represented, but in a greatly diminished fashion. Thus, from the rest 
of the facial region, as high as the lower border of the upper limb region, as defined 
by Beevor and Horsley, and, posteriorly, as far as the secondary sulcus in the foot 
of the ascending parietal gyrus, a slight degree of adduction (as far as the cadaveric 
position) is obtained on excitation. The relative degree to which this exists is shown 
in fig. 1 by the depth of the stippling. It need hardly be added that, of course, the 
movements of the face, jaws, and tongue noted to be represented in this region 
(Ferrieb, Schafer, Beevor and Horsley) also occur in concomitant association. 
This gradual decrease in representation from a focus or centre of most complete 
function is typical of all cortical motor representation, especially in the lower apes. 
Extrinsic Laryngeal Movements .—The movements of the larynx as a whole, 
* Coufirmed by Mott and Schafee, ‘ Brit. Med. Joarnal,’ May 17, 1890. 
