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PHYSIOLOGY FOR NURSES 



act as two (Iriiius, the lonscr segment vibrating more, 

 and the relaxed less, rapidly. At the bottom of our 

 ears we have a membrane (tympanic) familiarly known 

 as the "ear-drum" which can be relaxed or stretched 

 to respond to blows of different character. The nerve 

 terminals themselves are arranged to respond to waves 



Fig. 32. Tympanum of right side with the auditory ossicles in place ( Mor- 

 ris) : I, incus (like bicuspid tooth) with one process (_.?) attached to wall of 

 tympanum and the other running downwards to articulate at 9 and 8, the 

 stapes; 10, head of malleus attached to tympanic membrane. (From llowell's 

 Physiology.) 



of different lengths; i.e., vibrations which may be as 

 many as four thousand or as few as thirty to the second. 

 In man the external ear is of little use in gathering- 

 sound and concentrating it upon the drum, though it 

 seems to serve its purpose much better in many lower 

 animals. The tympanic membrane closes the auditory 



