THE BRAIN 



245 



I. Sensory areas, i.e. centres in which the conscious sen- 

 sations are formed. There are four such areas. 



(i) Centres for ordinary and tactile sensations. These 

 lie in the anterior and posterior central gyri, the posterior 

 parts of the frontal lobe, the paracentral lobe, and the gyrus 

 fornicatus (compare Figs. 21-24). 



FIG. 21. 



FIG. 22. 



CONVOLUTIONS OF THE CEREBRAL HEMISPHERES. 







The centripetal fibres of the corona radiata of the tactile 

 centres are the indirect processes of the posterior roots 

 (fibres of the fillet and anterior peduncle which pass through 

 the ventro-lateral nucleus of the thalamus opticus and thence 

 into the corona radiata). In this area the sensations of the 

 skin and organs are perceived. 



