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MANUAL OF PHYSIOLOGY. 



imperfect and unpleasant, for we should be wearied by the reit- 

 eration and persistence of the note to which the tympanic mem- 

 brane was tuned. But this does not occur; the tympanic mem- 

 brane has no self-tone, and no succession of vibrations follows the 

 first effect of the sound waves. 



FIG. 234. 



e.au.m 



Diagram of the tympanum, showing the relation of the ossicles to the 

 tympanic membrane and the internal ear. The tympanum is cut through 

 nearly transversely, and the cavity viewed from the front (left ear). (Schiifer.) 

 m.t, Membrane of the drum, to which the handle of the malleus is attached 

 at w. TO, head of malleus, which is held in position by its suspensory ligament 

 ./.m., and external ligament l.e.m; {., long process of incus connecting mal- 

 leus and st. stapes, the base of which closes oval opening of the vestibule. 

 e.au.m, external auditory meatus. i.au.m, internal auditory meatus, where 

 the two parts of the auditory nerve enter, a and b. 



The existence of any special note of its own is prevented by 

 its conical shape, which is partly due to the traction of the handle 

 of the malleus. If a stretched membrane, such as that of a drum, 

 be drawn out at its centre so that it is no longer a flat surface, 

 then its tension is different at the centre and the periphery, being, 



