612 



NERVOUS SYSTEM. 



convolutions (Charcot). A few of the converging fibres from the hemispheres 

 pass directly through the internal capsule and have no connection with the 

 corpora striata and optic thalami. 



From the internal capsule, the fibres pass in the crus cerebri to the upper 

 border of the pons Varolii. The motor fibres pass through the pons as lon- 



FIG. 225. Diagrammatic representation of the direction of some of the fibres in the cerebrum (Le Bon). 



gitudinal fibres, go to the anterior pyramids of the medulla oblongata, where 

 most of them decussate, and thence to the pyramidal tracts of the spinal 

 cord. The sensory fibres go to the posterior part of the cord. The converg- 

 ing cerebral fibres are re-enforced, in their downward course, by fibres from 

 the tubercular quadrigemina and the gray matter of the pons Varolii. Cer- 

 tain fibres go to the olivary bodies in the medulla oblongata. A more extend- 

 ed description of these fibres will be given in connection with the physiologi- 

 cal anatomy of the medulla. 



Cerebral Localization. The observations of Flourens (1822 and 1823) and 

 his immediate followers, which seemed to show that the cerebrum was neither 

 excitable nor sensible to direct stimulation, have been so completely contra- 

 dicted by the experiments of Fritsch and Hitzig (1870), Ferrier, Munk, Hors- 

 ley and many others, that the question of the existence of motor and sensory 

 centres especially motor centres hardly admits of discussion. The negative 

 results obtained by Flourens were probably due to severe haemorrhage, which, 



