706 



FUNCTIONS OF THE CEREBELLUM 



[CH. XLIX. 



remainder of the internal ear is concerned not in hearing, but in 

 the reception of the impressions we are now studying. Within the 

 vestibule are two chambers made of membrane, called the utricle 



and the saccule; these com- 

 municate with one another and 

 with the canal of the cochlea. 

 Within each bony semicircular 

 canal is a membranous semi- 

 circular canal of similar shape. 

 Each canal is filled with a 

 watery fluid called endolymph, 

 and separated from the bony 

 canal by another fluid called 

 perilymph. Each canal has a 

 swelling at one end called the 

 ampulla. The membranous 

 canals open into the utricle; 

 the horizontal canal by each of 

 its ends ; the superior and pos- 

 **>'. vertical canals by three 



Openings, these tWO Canals being 



""*' connected at their non-ampul- 



lary ends. 



Fig. 512 shows in transverse section the way in which the 

 membranous is contained within the bony canal ; the membranous 



fibrous bands connecting the periosteum to 4, the 



FIG. 513. Section through the wall of the ampulla of a semicircular canal, passing through the crista 

 acoustica. i, Epithelium ; 2, tunica propria ; 3, librous layer of canal ; N, bundles of nerve-fibres ; 

 C, cupula, into which the hairs of the hair-cells project. (After Schafer). 



canal consists of three layers, the outer of which is fibrous and 

 continuous with the periosteum that lines the bony canal ; then comes 

 the tunica propria, composed of homogeneous material, and thrown 

 into papillae except just where the attachment of the membranous to 



