Chap. XXJ 



SUMMARY 



435 



Ear . 



Pinna, 

 auricle 



or 



External Ear. 



Structure 



Fxmction 



Middle Ear - 



Cartilaginous 

 framework, 

 some fatty 

 and muscular 

 tissue, cov- 

 ered with 

 skin. 



Collects sound- 

 waves and re- 

 flects them 

 into the audi- 

 tory canal. 

 ' 1 in. long, partly cartilage, 



partly bone. 

 Closed inter- 

 nally by 

 the drum- 

 membrane 

 Hairs directed outward. 

 Ceruminous glands secrete 

 a yellow, pasty substance. 

 An irregular cavity in the temporal bone. 

 Five or six drops of water will fill it. 

 r Malleus (hammer). 

 < Incus (anvil). 

 I Stapes (stirrup). 

 ■ Fenestra ovalis — closed by 

 a membrane and the 

 stapes. 

 Fenestra rotunda — closed 



by a membrane. 

 Eustachian tube — con- 

 nects with the pharynx, 

 allows entrance of air. 



Auditory 

 canal 



Membrana 



tympani. 



Bones 



Openings 



