178 



SENSE OF HEARING. 



and its centre affords attachment to one extremity of the chain of 

 small bones, to the handle of the malleus. The proper tissue of the 

 membrane is dry, and it is generally esteemed to be devoid of fibres, 

 vessels, and nerves. Sir Everard Home, 1 however, asserts, that it is 

 muscular; that its fibres run from the circumference towards the cen- 

 tre, and are attached to the malleus ; and that if the membrane of the 

 human ear be completely exposed on both sides by removing the con- 

 tiguous parts, the cuticular covering be washed off from its external 

 surface, and it be placed in a clear light, the radiated direction of its 

 fibres may be easily detected. This fibrous arrangement, Sir Everard 

 conceives to be muscular, and on this he founds some ingenious specu- 

 lations, to be hereafter noticed, regarding the appreciation of sounds. 

 The discovery of a fibrous structure would, however, by no means 

 prove, that the membrane is capable of contracting; or that it is 

 formed of muscular tissue. Many ligaments, which consist of gelatin, 

 and are, consequently, not contractile like muscles, are distinctly 

 fibrous in their arrangement. The same may be said of tendons, whose 

 utility, as conductors of force developed by muscle, would be mate- 

 rially interfered with, were they possessed of contractility. Again : 

 Messrs. Ruysch, 2 Sir Everard Home, and Sir Charles Bell, 3 affirm, 

 that the membrana tympani is vascular, Sir Everard asserting, that 

 the vessels, in their distribution, resemble those of the iris, and are 

 nearly half as numerous ; their general direction being from the cir- 

 cumference to the handle of the malleus. It is not easy to account 



for this discrepancy amongst practical ana- 

 tomists as to the structure of the membrana 

 tympani. A part of it is probably refer- 

 able to some having directed their attention 

 to the membrane proper; and others to the 

 membrane with its dermoid coverings, .which 

 are highly vascular. 



The inner extremity of the drum is 

 partly osseous, partly membranous. Nearly 

 opposite the centre of the membrana tym- 

 pani is the foramen ovale seu vestibulare, 

 called, also, ihefenestra ovalis seu vestibu- 

 laris, situate vertically, and forming a com- 

 munication between the middle and internal 



T , . , , , r 



ear. It is closed by a membrane consist- 



m Head of the malleus below g, like the membrana tympani, of three 



la yers-to which is attached the base of the 

 stapes, the inner extremity of the chain of 



vi , .1 . i , i 



ossides that stretches across the cavity. 



"h/ilnw t>iA fnvampn nvnlp i<3 thp 



Deiow tne loramen ovaie 



Ossicies of the left Ear articulated, 



and seen from the outside and be- 



i ow . 



the root of which is the short process, 



h. Manubrium, or handle, sc. Short 



cms; and ic, long crus of the incus, 



The body of this bone is seen articu- 



lating with the malleus, and its long 



crus, through the medium of the orbi- D0n y projection called the promontory ; and 



cular process, here partly concealed, *> * *> . . -t . n j 



Base of the beneath this, again, a second opening, called 



with the stapes, s. 



"* 



, , 



foramen rotundum seu cochleare, and fenes- 



1823. 



i Philos. Transact, for 1800, P. i. p. 1, and Lectures on Comp. Anat.,iii. 262, Lond 



9 Epist. Anat. octava, p. 10. Amstel., 1724. 



8 Anat. and Physiol., edited by J. D. Godman, 5th Amer. edit., ii. 253, New York, 1827 



