1885.] on the Motor Centres of the Brain, &c. 255 



Rolando being another pioneer of cerebral topograi)hy. Now it is 

 around this fissure of Rolando that tlie motor side of the centres for 

 voluntary movement is situated ; and when this portion of the cortex 

 is irritated by gentle electrfc currents, a constant movement follows 

 according to the part stimulated. 



Because of their upward direction, the convolutions bounding the 

 fissure of Rolando are called respectively the ascending frontal and 

 ascending parietal convolutions. 



Now here, at the lowest end of the fissure of Rolando, we find 

 motor areas for the movement of both sides of the face, that is to say, 

 that as regards this particular piece of the cortex, it has the power of 

 moving not only its regular side of the face, the right, but also the 

 left — that in fact both sides of the face move by impulse from it. 



Higher up we find an area for movement of the oj^posite side of 

 the face only. I reserve for a moment the description of this portion 

 of the brain, and jDass on to say that above these centres for the face 

 we find the next is for the ujDper limb, and most especially the common 

 movement of the upper limb, viz. grasping, indeed the only forward 

 movement which the elbow is capable of, namely flexion. The 

 grasping and bringing of an object near to us is the commonest 

 movement by far, and we find here that this centre is mainly con- 

 cerned in it. Behind the fissure of Rolando, Dr. Ferrier placed the 

 centres for the fingers. 



Next above the arm area is a portion of the cortex which moves 

 the lower limb only, and in front of this again is an area for consonant 

 action of the opposite arm and leg. 



Let me here remind you that this being the left hemisphere, these 

 are the centres for movement of the opposite, that is the right limbs, 

 and that in the other hemisjDhere there are corresponding areas for the 

 left limbs. 



Thus here we have majDped out those portions of the cortex which 

 regulate the voluntary movement of the limbs. So far I have 

 omitted mention of the muscles of the trunk, namely, those which 

 move the shoulders, the hips, and bend and straighten the back. 

 Dr. Ferrier had shown that there existed on the outer surface of the 

 cortex, here, a small area for the movement of the head from side to 

 side. 



Professor Schafer and myself have found that the large trunk 

 muscles have special areas for their movement, ranged along the 

 margin of the hemisphere, and dipj)ing over into the longitudinal 

 fissure. Thus all the muscles of the body are now accoimted for, and 

 I will first draw special attention to the fact that they are arranged 

 in the order, from below upwards, of face, arm, leg, and trunk. 



The consideration of this very definite arrangement led Dr. 

 Lander Brunton to make the ingenious suggestion that it followed as 

 a necessary result of the progressive evolution of our fac-ulties. For 

 premising in the first place from well- ascertained broad generalisa- 

 tions that the highest centre, physically speaking, is also the highest 



