THE CORTEX OF THE FORE-BRAIN, ETC. 



83 



larger one in the centrum semiovale, or by a still more extensive 

 one in the cortex. In the capsule the fibres are crowded closely 

 together, which, higher up, are spread over a greater surface. 

 For example, a great extent of cortex (both central convolutions 

 and the adjoining portions of the frontal and parietal convolu- 

 tions) would have to be destroyed in order to produce a complete 

 opposite hemiplegia. The same effect might be caused by a 

 smaller lesion in the centrum semiovale under the central con- 

 volutions, whereas the symptom-complex in question could be 

 produced by a very small lesion in the posterior branch of the 

 inner capsule. In cases of hemiplegia, therefore, we at once 



Centrum 

 semiovale. 



Capsula 

 intern a. 



Cms cerebri. 



FIG. 48. 



suspect that the disease is located in the neighborhood of or in 

 the internal capsule, unless additional symptoms point directly to 

 some other region of the brain. Hemiplegias from disease 

 of the cortex are very rare. Hemiplegias arising from diseased 

 foci in the deeper-lying portions of the central nervous system 

 are still rarer, and are generally associated with cranial-nerve 

 symptoms, which indicate the seat of the lesion. 



On the other hand, both anatomical considerations and 

 clinical experience teach us that cerebral diseases which affect 

 single members of the body (one hand, for instance) very seldom 

 have their seat in the capsule, because the fibres there are so 



