686 



FUNCTIONS OF THE CEREBELLUM. [CH. XLIX. 



of the cochlea. Within each bony semicircular canal is a mem- 

 branous semicircular canal of similar shape. Each canal is filled 

 with a watery fluid called endolymph, and separated from the 



Fig. 509. Section of human semicircular canal. (After Riidinger.) 



i, bone ; 2, periosteum ; 3, 3, fibrous bands connecting the periosteum to 4, the outer 

 fibrous coat of the membranous canal ; 5, tunica propria ; 6, epithelium. 



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 ; 



Fig. 510. Section through the wall of the ampulla of a semicircular canal, passing 

 through the crista acoustica. i, epithelium; 2, tunica propria; 3, fibrous layer of 

 canal ; N, bundles of nerve-fibres ; C, cupula, into which the hairs of the hair-cells 

 project. (After Schafer.) 



the superior and posterior vertical canals by three openings, these 

 two canals being connected at their non-ampullary ends. 



Fig. 509 shows in transverse section the way in which the 

 membranous is contained within the bony canal ; the membranous 



