Deafness practically illustrated / [James Yearsley].

  • James Yearsley
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

Credit: Deafness practically illustrated / [James Yearsley]. Source: Wellcome Collection.

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    ness is also produced, but with far less frequency, by disease of the auditory nerve itself. There are certain practical truths relative to deaf- ness, which, to simplify the subject, it may be as well to enumerate; they are proved to us by daily expe- rience, and are sufficient to guide us in the choice and application of the various therapeutic means proposed for its relief. Thus, it is known, that if, from any cause, air cannot reach the membrana tympani through the external auditory passage, the faculty of hearing is nearly or quite extinguished. Again, it is known, that the elasticity of the membrana tympani is essential to hearing, so that, when, by disease of the membrane itself, or by an alteration of the surrounding parts, it becomes thickened, the function of hearing is impaired, and can only be restored by the restoration of the membrane to its normal condition, or by making a passage through it for the transmission of sound. Many persons are altogether deprived of this mem- branous partition, and yet preserve the function of hearing in tolerable acutencss. It is also observed, that when the Eustachian pas- sages, which serve as inlets for atmospheric air, and as outlets for the secretion of the lining membrane, are obstructed, deafness is the result; and the lost function is restored only with the re-establishment of these natural passages. With these fixed principles before us, I will proceed to the more immediate object of this chapter—namely, “ An Outline of the Principal Diseases of the Ear, and their Treatment.” The most natural division of the subject which presents itself, with reference to loss of hearing, is
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