Deafness practically illustrated / [James Yearsley].

  • James Yearsley
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

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

    41/200 page 29
    chian canal. In addition to the means described, there exists another very delicate and beautiful organism, intended to assist in maintaining the integrity of the passages leading to the ear. These are the innumerable cilia, discovered in the tuba Eustachii, by MM. Va- lentin and Purkinje. The cilia themselves consist of transparent filaments, situated on the surface of the mucous membrane, and are endued with a power of active motion. ‘They are only visible with the aid of a powerful microscope, being of a diameter not exceed- ing +y4o7 Of an English inch. Ciliary motion consists in the regular and continued vibration of these minute filaments; although so exceedingly small, their great number and constant oscillatory movements are sufli- cient to occasion determinate currents in the fluid on the surface of ciliated membranes, and even to remove by their action fine particles of dust, which may come in contact with them. It will be easily seen, that the ciliary bodies are of great utility in preserving the healthy condition of the mucous membrane of the Eustachian tubes; more especially as these tubes, from their cartilaginous structure, admit in themselves of such limited motion. Such are the chief provisions of nature for the conservation of these canals, to which such frequent reference has been made; provisions that, during the continuance of health, are abundantly suffi- cient for the fulfilment of their designed purpose. But when from accidental causes, (and these causes are both numerous and important,) as dyspepsia, fevers, catarrhal complaints, dentition, &c., the Eustachian tubes become inflamed, or in a state of irritation, the mucous membrane throws out a larger amount of secre- tion than usual; and if this secretion be in greater
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