Carpenter's principles of human physiology . he membrana tympani positions as m Man, are seen the fenestra ovalis and rotunda; k. Eustachian tube ; I, vestibule ; rLpirrVirpp ? »». semicircular canals; n, cochlea; o, auditory nerve; p, canal for carotid wieii uni«« pidiieb uemg artery. ^ part Qf glenoi(1 fossa. r> styloid process; *, mastoid process. nearly at right angles to one another; but it is now no longer held, because it can be easily shown thatthe direction of sounds cannot be estimated except by two or more simultaneousor consecutive observations. If a sound of moderat
Carpenter's principles of human physiology . he membrana tympani positions as m Man, are seen the fenestra ovalis and rotunda; k. Eustachian tube ; I, vestibule ; rLpirrVirpp ? »». semicircular canals; n, cochlea; o, auditory nerve; p, canal for carotid wieii uni«« pidiieb uemg artery. ^ part Qf glenoi(1 fossa. r> styloid process; *, mastoid process. nearly at right angles to one another; but it is now no longer held, because it can be easily shown thatthe direction of sounds cannot be estimated except by two or more simultaneousor consecutive observations. If a sound of moderate intensity be made at apoint equidistant from the two ears, we are unable to judge of its position unlesswe are aided by the visual sense—and the difficulty of indicating accuratelythe position of a cricket or deathtic, is well known. The curious movementswitnessed by M. Flourens* after section of one or more of these canals (§ 480), * See Cyons Researches on the Ear, in Nature, 1S78, Oct. 10, with Crum Brownscriticisms upon 774 OF THE ORGANS OF THE SENSES, AND THEIR FUNCTIONS. to which reference has already been made, have led to another theory of theiruse. Flourens observed that section of a membranous canal was alwaysfollowed by movements of the head or even of the body of the animal in thedirection of the divided canal, and hinted that they were concerned in the co-ordination of movements. This suggestion was elaborated by Goltz into whathas been termed the statical theory, namely—that the termination of thenerves in the ampullae, may be supposed to be stimulated by pressure or bystretching. The endo-lymph necessarily presses most upon that part of thewall of the canal which is situated at the lowest point, and each position of thehead will correspond to a particular distribution of pressure, and therefore, toa particular form of nerve stimulation. We have thus a special sensationcorresponding to each position of the head. The importance of a knowledge ofth
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
