234 THE INTERNAL EAR. 



pass on to the labyrinth, the vibrations of the membrane, 

 produced by vibrations of the air. The outmost bone 

 is the malleus or hammer-bone, L j the inmost, the stapes 

 or stirrup-bone, S ; and the one between, the incus or anvil- 

 bone, H. 



FIG. 59. The tympanic cavity, C, C, and its bones, considerably magnified. G, 

 the inner end of the external auditory meatus, closed internally by the conical tym- 

 panic membrane; L, the malleus, or hammer-bone; //, the incus, or anvil-bone; 

 S, the stapes, or stirrup-bone. 



15. The Internal Ear, or Labyrinth, consists of cham- 

 bers and tubes hollowed out in the inner part of the 

 temporal bone, T, Fig. 6, and containing thin bags and 

 tubes, filled and surrounded by watery liquid. Inside 

 these bags and tubes the fibres of the auditory nerve 

 end. Its middle chamber, called the vestibule ( V, Fig. 58), 

 has an opening, the oval foramen, o, in its outer side, into 



use ? Number and arrangement of the bones in the tympanum ? 

 Their use ? Names and position of these bones ? 



15. Of what does the internal ear consist ? Where do the fibres of 

 the auditory nerve end ? Name of the middle chamber of the internal 

 ear? Where is the oval foramen, and what fits into it? Where are 



