114 



ZOOLOGY. 



pass into it, and terminate by a cul-de-sac over the drum of 

 the ear. It is in this tube or canal that we find the small 

 sebaceous follicles which secrete the cerumen that is, the 

 wax of the ear. 



Tc h g e" e" f e' b 



Fig. 73. Auditory Apparatus in Man.* 



The middle ear is composed of the tympanum, of the cavity 

 of the tympanum, and parts connected with it. 



The cavity of the tympanum is a cavity of an irregular form, 

 hollowed out in the substance of the petrous part of the tem- 



* Vertical section of the auditory apparatus, somewhat magnified as respects 

 the deeper structures. a, external ear ; I, lobe of the ear ; c, the eminence 

 called antitragus; d, concha, continuous with the external auditory canal (f) ; 

 ee, petrous part of the temporal bone ; e , mastoid process ; e", articular or 

 glenoid cavity for the condyle of the lower jaw; e", styloid process of the 

 temporal bone ; e'" f , extremity of the canal by which the internal carotid 

 artery passes into the interior'of the cranium ; f, auricular canal ; g, mem- 

 brana tympani ; h, cavity of the tympanum ; the ossicula auditus have been 

 removed ; i, opening in the wall of the tympanum leading to osseous cells ; 

 the fenestra ovalis and rotunda are close to this opening : Jc, Eustachian 

 tube; , vestibule ; m, semicircular canals ; , cochlea; o, acoustic nerve. 



