A treatise on the diseases of the ear including the anatomy and physiology of the organ together with the treatment of the affections of the nose and pharynx which conduce to aural disease . sible. When, however,the stapes is forced against the fenestra ovalis, the pressure com-municated to the fluid of the labyrinth acts upon the membrane ofthe fenestra rotunda, causing it to yield as far as its elasticity willpermit. Inward pressure of the base of the stapes is likewiseresisted by the membrane covering the fenestra ovalis. From the account thus given of the ossicles and their con- 38 TIIK OU
A treatise on the diseases of the ear including the anatomy and physiology of the organ together with the treatment of the affections of the nose and pharynx which conduce to aural disease . sible. When, however,the stapes is forced against the fenestra ovalis, the pressure com-municated to the fluid of the labyrinth acts upon the membrane ofthe fenestra rotunda, causing it to yield as far as its elasticity willpermit. Inward pressure of the base of the stapes is likewiseresisted by the membrane covering the fenestra ovalis. From the account thus given of the ossicles and their con- 38 TIIK OUGAX OF IIEAiaXG. iiections and movements, the mode in which the vibrations oftlie membrana tympani are conveyed to the labyrinth will beeasily understood. The transverse vibrations of the membranecause the malleus and incus to oscillate around their commonaxis ; the movements of the long process of the latter bone causecorresponding movements of the stapes against the fenestra vibrations set up wave-movements in the fluid of thelabjrinth, the membrane of the fenestra rotunda yielding to thel)ressure thus applied. Muscles of the Tympanum.—The tympanum contains two small. Fig. 12. The Malleus axd Ixcus. {Helmholtz.) The line aba touches from above downwards the apex of the short process of the incus, of thelong process, and of the handle of the malleus; h, the head of the malleus; i, the bodj ofthe incus; sp, prominent bonier, boumlintj head of malleus; , remains of long processof malleus; , attachment of tensor tympani muscle. muscles, attached to the malleus and stapes respectively, andnamed the tensor ti/mjmni and the stapedius. The foiiner consistsof a tapering, fleshy portion, and a slender tendon. The fibresarise from the margin of the anterior opening of the carotid canal,from the cartilaginous end of the Eustachian tube and the ad-joining portion of the sphenoid bone, and from the inner concavewall of the boin^ canal. They are often closely connected
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Keywords: ., boo, bookcentury1800, bookdecade1890, booksubjectear, bookyear1894
