NO. 



EAR EXOSTOSES HRDLICKA 43 



itself plain to me many years ago during my ethnological investigations of skulls 

 from the northern portions of the Pacific coasts. I refer to the more diffuse 

 hyperostosis which he has exhibited in his first case. That, I should not call 

 an exostosis at all. Diffuse hyperostosis is quite different from a genuine 

 exostosis. Inasmuch as exostoses have a very typical situation, this interpreta- 

 tion is very plain." 



Hyperostosis of the external auditory meatus always limits itself to the pars 

 tympanica, whilst the adjacent squamous portion of the bone has no bony pro- 

 tuberance The entire pars tympanica may become hyperostotic. 



For Lake (1898) hyperostosis is distinct from exostosis, being 

 "a. more or less uniform bony stricture of the external meatus." 

 Sabroux (1901, p. 13) distinguishes between exostoses and osteomata, 

 believing the two to dififer anatomo-pathologically ; but gives no satis- 

 factory rule for differentiating the two. 



Korner (1904, pp. 106-7) thus imperfectly distinguishes the two 



forms : 



Of the exostoses, the button- to semiglobular forms are found near the 

 antero-superior border of the drum, in the vicinity of the location, still open at 



birth, of the original tympanic ring. They remain mostly very small The 



hyperostoses are found as a rule in the outer part of the bony meatus. In accord 

 with the differing participation of the tympanic bone in the formation of the 

 lower portions of the bony meatus, they reach up to the middle, seldom to the 

 upper third of the lumen of the canal. They develop usually synchronously on 

 the anterior and the posterior wall, seldom also on the floor of the meatus, 

 in such a manner that the remaining opening of the canal becomes pear- 

 shaped After what was said it seems that the frequently mentioned occur- 

 rence of multiple exostoses in one ear is really to be assumed as a combination 

 of ex- and hyperostoses ; only the small exostoses at the upper border of the 

 drum do occasionally occur in a multiple number. ^. . . . 



Bezold and Siebenmann (1908, p. 102) offer a somewhat peculiar 

 concept of the hyperostoses and exostoses and decide against speaking 

 of them separately: 



We call exostoses small round bony growths which are usually found as little 

 white circumscribed elevations in groups of two or more on both sutures of the 

 deepest part of the os tympanicum to the horizontal part of the scale of the 

 temporal bone. One protuberance is usually directly in front, another close 

 behind the short process of the hammer in the drum membrane. A third one 

 often protrudes between the two. Hyperostoses present themselves more in the 

 form of diffuse bulgings of the anterior lower, and sometimes also posterior 

 lower wall. A crosscut through the meatus has consequently the shape of a 

 pear with the point downward. We shall speak about exostoses and hyperostoses 

 together, as they are found not infrequently in the same ear. 



Jackson (1909) divides the neoplasms merely into: i, those that 

 entirely block the meatus ; 2, those that do so partially ; and 3, those 

 that scarcely affect it, causing merely some narrowing. 



