Organ of Hearing. 



231 



Eminent, 

 can. 



Canalispro 

 ore tyinpam 



-Isthmue tulae 



CelMae 

 mastoideae 



frtfie. 



pliaryng. 

 tubac 



314, The Tympanic Cavity and Eustachiaii Tube 



in section. 



Orifice of t. 1 ^ 



Camaltc. chordae 



315. The Inner Wall of the Tympanic Cavity. 



Magn. = 3. 



The tympanic cavity, Cavum tympani, lies to the inner side of 

 the Membrana tympani, is lined by mucous membrane, and communicates 

 by means of the Eustachian tube with the pharynx. At the inner 

 wall of it are: the* Fenestra ovalis, leading into the vestibule of the 

 labyrinth; the Fenestra rotunda, into the cochlea (closed by a thin mem- 

 brane, Membrana tympani secundaria\; between both fenestrae, the pro- 

 montory, Promontorium, marked by a groove, Sulcus Jacobsonii ; behind 

 the Fenestra ovalis the hollow pyramid, Eminentia pyramidalis, whose summit 

 projects forwards towards the Fenestra ovalis; above the Fenestra ovalis 

 the lower wall of the Canalis Fallopiae; above the promontory the Semi- 

 canalis tensoris tympani, ending with the conical Rostrum cochleare. 



