742 



FUNCTIONS OF THE CEREBRUM 



[CH. L. 



area connected with the movements of the hand (Bastian's cheiro-kincesthetic area} 

 near the middle region of the Rolandic cortex, and finally the movement of writing 

 is accomplished. The diverse symptoms exhibited by patients suffering from 

 various forms of aphasia can be all explained by more or less extensive damage 



FIG. 455. Outer surface of human brain, showing Flechsig's developmental zones; primary (110) 

 darkly shaded ; intermediate (1131), less deeply shaded ; terminal (32 36), not shaded. (Flechsig.) 



either to the centres themselves or to the association tracts which connect them. 



In the cerebral convolutions the fibres become myelinated in a strictly 

 regular sequence; some convolutions have their fibres medullated three months 

 before birth, while in others complete myelination has not occurred six months later. 



FIG. 456. Inner surface of same. (Flechsig.) 



Fibres of equally great importance become medullated at the same time ; those of 

 primary importance first, and so on. In this way, myelogenetic cortical fields can 

 be mapped out, which retain their contours for some time. Thirty-six of such fields 

 were made out by Flechsig, and can be divided chronologically into three groups, 

 primary, intermediate, and terminal 



The primary fields are darkly shaded in the accompanying diagrams (figs. 455 

 and 456). 



