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    THE ORGAN OF HEARING: THE EAR

    291. What can you say of the construction of the ear?HBH 129.3

    This organ, which, with that of sight, ministers to the intellectual and moral wants of man, as well as the physical, and relates us in duties, interests and pleasures to our fellows, exhibits in its structure a greater complexity than any other part of the human organization. The ear may be divided into the outer, the inner, and middle parts, and the auditory nerve. The outer part consists of the external ear, and the tube which leads to the membrane of the tympanum. The external ear is composed of cartilage, covered with a delicate skin, supplied with nerves and blood vessels. It inclines forward and is adapted to collect sounds, which it conveys through the tube. This tube is nearly an inch in length, made partly of cartilage and partly of bone. It has a number of small glands which secrete the wax. Its entrance is guarded by stiff hairs to prevent the ingress of foreign substances to the ear. The middle part of the organ embraces the tympanum and its membrane, the small bones of the ear, and the eustachian tube. This tube passes to the throat a little back of the palate. It is about two inches long, the largest at the throat. The membrane of the tympanum is placed at the bottom of the external tube. This membrane is placed obliquely, inclining downward and inward; it is tense, thin, and transparent. The tympanum, between the external and internal ear, is of irregular cylindrical form, with several openings. It contains the four little bones of the ear called the hammer, the anvil, the round bone, and the stirrup. Muscles of very small size move these bones in various directions. The internal ear is composed of three parts, and is situated in a part of the temporal bone near the base of the skull. Its parts are called the cochlea, the vestibule, and the semicircular canals. The first resembles the shell of a snail. The vestibule is a sort of porch or entry, which communicates with all the other parts. The three semicircular canals are all back of the cochlea and vestibule. The auditory nerve is distributed to the semicircular canals, the cochlea, and the vestibule, terminating in the form of a pulp.HBH 129.4

    292. What can you say of the action of this organ?HBH 131.1

    As the pupil of the eye contracts or dilates according to the amount of light transmitted to it, so the nerves of the ear act upon the muscles of the internal ear in proportion to the softness or harshness of the sound transmitted. The muscles move the chain of small bones so as to conduct the vibrations of sound across the tympanum to the internal ear. The contained air of the tympanum reverberates the sound, which is strengthened and modified by reflection from the walls, cells, and spaces of the ear. The impression of this sound is taken cognizance of by the auditory nerve. Of the peculiar action of this nerve, we shall have to content ourselves with admiring its wonderful operation without being able to solve the mystery as to how it acts. Of the philosophy of sound we can only say here that it is a vibration of the air caused in various ways, as by the striking of a bell, by singing of birds, or by the human speech.HBH 131.2

    293. What can you say in general terms of the ear?HBH 131.3

    It is one of the most useful of the organs of sense. It is attuned to the varied and sweet sounds of nature. Through it the persuasive tones of eloquence exert more power to stir or to stay the passions of man than all the arguments the ablest reasoner can present to the judgment. How important that we carefully guard and preserve this organ. It will be perceived that persons on becoming blind have a more acute sense of hearing than they had before. This hearing in some respects compensates for loss of sight.HBH 131.4

    294. Is the ear very liable to disease?HBH 132.1

    There are very few causes of derangement of the ear. Ear wax sometimes hardens in the ear. This can frequently be entirely relieved by several times dropping into the ear a few drops of pure sweet oil, and swabbing out the ear thoroughly with a little warm soft water and castile soap. Colds in the head, if they affect the hearing, must be very carefully avoided. In dullness of hearing, while you can hear distinctly the ticking of a watch placed against the side of the head, there is hope. Throat diseases, and scarlet fever, are very liable to leave children hard of hearing. This difficulty, as well as a permanent discharge from the ear, usually results from taking cold while recovering from the above diseases. The greatest care should be used that such results should not follow scarlet fever, etc. The difficulty may be outgrown, if not it is likely to grow worse as life advances.HBH 132.2

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