[ 163 ] 



SECT. XVI. 



OF .HEARING. 



247. SOUND, which is excited by the collision of 

 elastic bodies and propagated by the air, is perceived 

 by the sense of hearing,* and is first received by the 

 conchiform cartilaginous external ear,f which few of 

 our countrymen have the power of moving. J By this 

 it is collected; then conveyed into the meatus audi- 

 torius, which is anointed by a bitter cerumen ; (A) 

 and strikes against the membrana tympani, which is 

 placed obliquely in a circular furrow of the temporal 

 bone and separates the meatus from the internal ear. 



248. Behind this membrane lies the middle portion 

 of the ear, the cavity of the tympanum, whose fundus 

 is directed upwards and inwards. 



It contains three j| ossicula auditus: of which the 

 exterior, or malleus, adheres by its manubriuni to the 

 membrana tympani, is generally united in the adult 



* Sommemng,s4bildungdesmenschlichenH3rorg-ans. Franckfurt. 1806. fol. 



t B. S. Albinus, Annotat. Academ. L. vi. tab. iv. 



% J. Rhodius ad Scribon. Largum. p. 44 sq. 



J. Alb. Fabricius, De Hominibus ortu non differ entibus. Opuscul. p. 441. 



Ch. Collignon, Miscellaneous Works. Cambridge. 1786. 4to. p. 25 sq. 



Consult J. Haygarth, Med. Obs. and Inquiries, vol. iv. p. 198 sq. 



|| The existence of a fourth bone (called Lenticular], commonly admitted 

 since the time of Franc. Sylvius, I have disproved at length in my Osteology. 

 p. 155 sq. edit. 2. It is wanting in the greater number of perfect examples 

 from adults, 



M 2 



