Chap, v.i THE EAR. 83 



into the pharynx. The instrument should now be 

 withdrawn until its point can be felt to rise again on 

 the posterior edge of the hard palate ; having arrived 

 at this point, the catheter should be pushed onwards 

 about one in-ch, and during its passage its point should 

 be rotated outwards through a quarter of a circle." * 

 This manoeuvre should engage it on the orifice of the 

 tube. 



Blood supply. The tympanum is supplied by 

 the following arteries : the tympanic of the internal 

 maxillary and internal carotid, the petrosal of the 

 middle ineningeal, and the stylo-mastoid of the pos- 

 terior auricular. It is the distribution of the main 

 trunk of the last-named vessel that gives some reason 

 for the practice of applying blisters behind the ear in 

 disease located in the deeper parts. The fact that 

 some of the tympanic veins end in the superior petrosal 

 and lateral sinuses, gives another explanation of the 

 frequent occurrence of thromboses of those channels 

 in inflammatory affections of the middle ear. 



The cliorda tynipani nerve, from its exposed 

 position in the tympanum, is very likely to be damaged 

 in suppurative disease of the middle ear ; and Urban- 

 tschitsch and Schulte have shown that such disease in 

 this part may be associated with anomalies of taste. 



The osseous labyrinth is formed independently 

 of the other bony parts of the ear. Portions of this 

 labyrinth have necrosed and have been expelled in 

 recognisable fragments. In a case recorded by Dr. 

 B.irr the whole of the osseous labyrinth (the cochlea, 

 vestibule, and semicircular canals) was removed entire 

 as a necrosed fragment from the auditory meatus. 



The connection between deafness or tinnitus 

 aurium and affections of the stomach has been worked 

 out in the following way (Woakes) : The labyrinth is 

 nourished only by the vertebral artery ; that vessel is 

 * Smith and Walsham's " Operative Surgery," p. 12. 2nd ed. 1876. 



