NERVE 117 



mainly receiving, just as we shall afterwards find the 

 pre-central is mainly discharging. The arrangement and 

 character of the cells in these two regions are distinctly 

 different. 



This area must be a sort of chart of the opposite side of 

 the body in which each part is represented. 



4. Connections with the Cerebellum. 



The ingoing fibres from the muscles and joints have been 

 seen to play an important part in guiding ordinary spinal 

 refles action. 



It has also been shown that by their connection with the 

 cerebral cortex consciousness is implicated and special sen- 

 sations produced (p. 115). 



Through their connection with the superior vermis 

 of the cerebellum they become associated with incoming 

 impressions from the skin and from special receptor 

 mechanism in the head, through the action of which the 

 position and movements of the head in space bring about 

 adjustments of the balance of the body. 



The eyes play a certain part in such adjustments, but 

 the special mechanism developed is the labyrinth of the 

 internal ear for which the cerebellum has developed as the 

 great receiving and reacting centre. The mechanism may 

 be studied as the labyrintho-cerebellar mechanism. 



Labyrintho-Cerebellar Mechanism. 

 I. Labyrinth. 



1. structure- 

 In the petrous part of each temporal body there is 

 a somewhat complex space, the bony labyrinth, consist- 

 ing of three separate parts. (1) The vestibule; (2) the 

 cochlea connected with hearing which will be considered 

 later ; and (3) three semi- circular canals opening from the 

 superior and posterior aspect of the vestibule (see p. 170) of 

 the internal ear. One lies in the horizontal plane and has a 



