310 



STUDIES IN PHYSIOLOGY 



HS.C 



against the inner ear, and the incus forms the connection 

 between these two bones we have just mentioned. 



General Structure of the Inner Ear. By far the most 

 complex portion of our auditory apparatus is the inner ear. 

 Indeed, so complicated is it that we shall not attempt to 

 describe minutely its various parts. In general, we may 



say that the in- 

 ner ear consists 

 of a succession 

 of small cavities 

 hollowed out of 

 the interior of 

 the hardest part 

 of the temporal 

 bone; that with- 

 in these cavities 

 lie, more or less 

 loosely, a series 

 of thin-walled 

 tubes and small 

 sacs which are 

 distended with 

 a watery fluid 

 known as en 1 - 

 do-lymph (Latin 

 endo = within 

 + lymplia = wa- 

 ter) ; that the spaces between these membranous cavities of 

 the ear and the outer bony walls are filled with liquid per'i- 

 tymph (Greek peri = around -f Latin lymplia = water) ; and 

 that finally, and most important of all, the fibers of the 

 eighth or auditory nerve run to certain portions of the 

 membranous sacs and tubes which are especially sensitive 

 to sound waves. 



The Structure and Functions of the Semicircular Canals. The 

 flattened portion of the stirrup bone is fastened to a thin- 



FIG. 144. Distribution of Auditory Nerve (dia- 

 grammatic) . 



A.N = auditory nerve. 



ASC, HSC, PSC = a swelling on each of the semi- 

 circular canals. 

 av = canal between utriculus and sacculus. 



c = canal between sacculus and cochlea. 

 Coch = cochlea. 

 S = sacculus. 

 U = utriculus. 



