Chap. V.] 



THE EAR. 



61 



cartilaginous part. The narrowest portion of the 

 meatus is about its middle. The outer orifice is ellip- 

 tical, with its greatest diameter directed from above 

 downwards ; therefore specula should be elliptical in 



Fig. 12. Section through the external Meatus, Middle Ear, and 

 Eustachian Tube (Tillaux). 



a, External auditory meatus; 6, tympanum ; c, Eustachian tube; d, internal 

 auditory meatus ; e t cochlea ; /, ossicles \ a, inembrana tympani ; h. styloid 

 process. 



shape rather than round. The inner end of the tube, 

 on the other hand, is slightly wider in the transverse 

 direction. Owing to the obliquity of the membrana 

 tympani, the floor of the meatus- is longer than the 

 roof. The cartilaginous segment of the tube presents 

 many sebaceous glands that may be the seat of minute 

 and very painful abscesses. It also presents numerous 



