Identifier: outlinesofhumanp00hayw (find matches)
Title: Outlines of human physiology; designed for the use of the higher classes in common schools
Year: 1834 (1830s)
Authors: Hayward, George, 1791-1863
Subjects: Physiology
Publisher: Boston, Marsh, Capen & Lyon
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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tube leads from the back part of thethroat, or fauces, as they are called, to the cavity of thetympanum. It is about two inches in length; partlybony and partly cartilaginous. It is lined by a mucousmembrane. Its two extremities are not of the samesize, the one opening in the fauces being somewhatlarger than the other. The internal ear is situated in a part of the temporalbone, near the base of the skull, which, from its stonyhardness, has been called the petrous portion. It iscomposed of three parts, the cochlea, the vestibule, andthe semicircular canals. The cochlea is so called from its SENSE OF HEARING. 173 resemblance to the shell of a snail. It is situated nearthe entrance of the Eustachian tube, and is the most an-terior part of the internal ear. It communicates withthe cavity of the tympanum and the vestibule. Thevestibule is situated in the central part of the internalear, and is, as its name imports, a sort of porch or en-try, which communicates with all the other parts. By
Text Appearing After Image:
A Map of the Ear. A The external auditory tube. B The membraneof the tympanum. C The Eustachian tube. D The hammer. £ Theanvil. F The round bone. Q The stirrup. H The oval opening./ The semicircular canals. J The vestibule. K The cochlea. means of the oval opening, (the foramen ovale) it com-municates with the tympanum, and over this openingis placed the small bone called the stirrup (stapes). Ithas communications also with the cochlea, the serai-15* 174 SENSE OF HEARING. circular canals, and internal auditory tube,—the onethrough which the auditory nerve passes to the internalear on its exit from the brain; and it is through theopenings which lead from the vestibule to the internalauditory tube, that the branches of the auditory nervego to the various parts of the internal ear. The three semicircular canals are situated behindthe cochlea and the vestibule, and they all terminate inthe latter. There is found in them a dark greyish semi-fluid substance, the use of which is unknown.

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