73 6 



THE CEREBRAL CORTEX. 



concerned with closure of the eyelids. On the other hand, stimula- 

 tion of the leg area, of the arm area, of the trunk area, and of most 

 of the upper part of the face area, produces movements which are 

 generally strictly confined to the muscles of the opposite side of the 

 body. But in the dog and rabbit, according to Exner and Paneth, 1 

 excitation of the whole of the cortical field of the facial produces 



bilateral effects. And 

 in the dog, according 

 to v. Bechterew, 2 ex- 

 citation of the centre 

 for the platysma my- 

 oides, and of the 

 centre for lateral 

 flexion of the trunk, 

 produces contraction 

 chiefly of the mus- 

 cles of the same side 

 of the body instead 

 of those of the op- 

 posite side. 



Details of the 

 representation of 

 muscular move- 

 ments within the 

 principal portions 

 of the motor or Ro- 

 landic region of the 

 monkey. — It is con- 

 venient for purposes 

 of description to dis- 

 tinguish five areas of 

 the motor cortex 

 (Fig. 336), as follows 

 — (1) The area con- 

 nected with move- 

 ments of the head 

 and eyes ; (2) the 

 area connected with 

 movements of the 

 face, including those 

 of the mouth, throat, 

 and larynx ; (3) the 

 area connected with 

 movements of the 

 upper limb ; (4) the 

 area connected with movements of the trunk muscles, including those of 

 the tail ; and (5) the area connected with movements of the lower limb. 

 These areas are not marked off from one another by fissures or other 

 anatomical boundaries, nevertheless their limits, as determined by the 

 excitation method, are sharp, and although, on exciting exactly at the 

 boundary between any two areas, movements of both parts may result, 



1 Arch./, d. ges. Physiol., Bonn, 1887, Bd. xli. S. 349. 



2 Neurol. Centralbl., Leipzig, 1888, S. 15. 



Fig. 336. — Diagrams of the motor zone of the monkey's brain, 

 showing the live areas into which it is divisible. A, lateral 

 or external surface ; B, mesial surface. 



