ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 
7 
area stimulated. As a general fact^ it may be stated that the shoulder muscles come 
into play most strongly when the electrodes are applied near the superior limit of 
the area, the muscles moving the forearm and wrist when they are applied near the 
central and inferior portions of the area, and the muscles of the wrist and fingers when 
applied along the posterior border. Here it is sometimes possible also to differentiate 
between the different movements of the fingers and wrist, for superiorly the exci- 
tation usually produces pronation of the hand with extension of the fingers and 
wrist, and inferiorly supination of the hand with flexion of the fingers. The produc- 
tion of these movements of the fingers is not confined to excitation of the ascending 
parietal gyrus, but in very many cases the same movements are produced by exciting 
the ascending frontal at the corresponding point just across the fissure of Rolando. 
The supination which frequently accompanies flexion of the fingers on excitation of 
the lower end of the posterior margin of the arm-area appears to be brought about by 
contraction of the supinator longus. But just in front of the centre for this movement 
is a considerable portion of the arm-area, excitation of which is invariably followed by 
biceps flexion and supination. This may therefore be regarded as a hicepfi-centre 
(nearly corresponding with that marked (6) by FERRiERt), although other muscles than 
the biceps are also brought into action when it is stimulated. It includes a portion of 
the ascending parietal and the adjacent part of the second frontal gyrus, and it abuts 
below on the face-area, and in front on the head-area.| Again the retraction of the 
shoulder and arm, which is produced by excitation at the upper part of the area on 
either side of the fissure of Rolando, is largely produced, as Ferrier has also shown, 
by the latissimus dorsi (although other muscles are also thrown into action), and might 
be described as the latissimus-centre. 
The face-area, although we have so called it for convenience sake, actually gives 
rise to movements not only of the facial muscles, but also of the whole of the upper 
part of the alimentary tube (mouth, throat, and larynx). It comprises the whole of 
the ascending parietal and frontal convolutions below the arm-area, extending down 
to the fissure of Sylvius, and including the external surface of the operculum. It is 
physiologically remarkable from the fact that many of the movements which result 
from its excitation are apt to be executed bilaterally, which is only exceptionally the 
case with excitation of the other areas (except that for the head and eyes). 
Excitation of the upper third or half of the area causes winking, or closure of the 
eyelids, elevation of the ala of the nose, and retraction and elevation of the angle 
of the mouth. This may be termed the upper face-centre. 
* Compare Ferrier, ' Roy. Soc. Proc.,' vol. 2.3, 1875. 
t A lesion of the ascending fi-ontal portion of tliis centre, producing paralysis of tbe hand and fore- 
arm, is shown by Ferrier in ' Functions of the Brain,' 2nd edition, fig. 113, p. 351. 
X The arm-area has, since our experiments, been carefully investigated by Dr. C. E. Beevor in 
conjunction with Professor Hokslet. The results at which they have arrived, and which are generally 
confirmatory of those here given, have been already communicated to the Royal Society. 
