MINUTE ANALYSIS OF CORTICAL CENTRES. 
159 
upper limb, as defined by Professor Ferrier, we find that the regions for the action 
of the larger joints are situated at the upper part of that area, close to the middle line, 
while those for the smaller and more differentiated movements lie peripherally at the 
lower part of the area. 
Axiom 2.—As a general rule, extension of all the joints, particularly of the wrist 
and elbow, is the most characteristic movement of the upper part of Ferrier’s arm 
centre ; while flexion is equally characteristic of the movements obtained by stimu¬ 
lating the lower part. Finally, between these two regions there is a small portion 
where alternate flexion and extension predominate, a condition to which we have given 
the name of confusion.* 
We shall now proceed to give by means of tables the details of the experiments 
upon which the foregoing axioms are based. 
In the following Table 2 we give general conclusions respecting the different move¬ 
ments of each joint obtained by stimulating the upper and lower half of the above- 
mentioned area. 
Table 2. 
Upper part of Area. Lower part of Area. 
Shoulder.— Advancing. Adduction (nil in lower r). 
Elbow .— Extension (uppermost v), Confusion Flexion (remaining -f). 
(second v). 
Wrist. — (1) Pronation (upper |). Supination (lower f). 
„ (2) Extension. Extension (flexion at end of action). 
Posterior part of Area. 
Digits. —Flexion. 
Thumb .— Flexion (nil in upper \). 
Anterior part of Area. 
Extension. 
Flexion-Extension. 
Expansion of the foregoing Table (compare Table 2). 
Shoulder .—In the above Table it will be noticed that rotation of the shoulder does 
not appear ; this movement, though frequently observed, is but one of association. 
Rotation out occurs as the result of stimulating the lower three-fourths of the area, 
at least of that part which lies in front of the fissure of Rolando. In almost every 
case this rotation outwards was accompanied by flexion of the shoulder, so that the 
elbow was brought forward as well as rotated outwards. 
Pure abduction was practically never seen by us, but it entered into the composi¬ 
tion of the advancing movement, which we have shown to be characteristic of the 
upper fourth of the area. It will thus be seen that the movement of the shoulder, 
which we have called advancing of the arm, is neither pure flexion nor pure abduction, 
but a combination of these two. 
Adduction is strongly characteristic of the movement of the shoulder in the lower 
* Here both, flexors and extensors are contracting at the same time, and consequently the joint is 
usually fixed in a median position, each group of muscles alternately dragging it in opposite directions. 
