. Human physiology. ike a circle of fire ? 20. What do you notice when you look at a sheet of white paper after gazing intently on a bright green object ? Explain the cause. LESSON XXXVI. THE EAR. The ear consists of three parts :—the external ear, the middle earor tympanum, and the internal ear or labyrinth. The last of thesedivisions is the essential part of the organ of hearing, the other twobeing concerned merely in the collection and transmission ofsound vibrations. The outer ear consists of the pinna (Lat. a wing), that partwhich projects from the side of the head, and the auditory canal
. Human physiology. ike a circle of fire ? 20. What do you notice when you look at a sheet of white paper after gazing intently on a bright green object ? Explain the cause. LESSON XXXVI. THE EAR. The ear consists of three parts :—the external ear, the middle earor tympanum, and the internal ear or labyrinth. The last of thesedivisions is the essential part of the organ of hearing, the other twobeing concerned merely in the collection and transmission ofsound vibrations. The outer ear consists of the pinna (Lat. a wing), that partwhich projects from the side of the head, and the auditory canal. The pinna, being concave, is especially adapted for the collection of soundwaves which are reflected by it into the canal. It consists of a cartilaginousframework, surrounded by a certain amount of fatty tissue and a few smallmuscles, the whole being covered with integument. The pinna is throwninto several elevations and depressions, the names of which may be learntfrom the accompanying illustration. THE EAR 217. Fig. 202.—Outer sur-face of the Pinna ofthe Bight Ear. 1, helix ; 2, antihelix; 3, tra-gus ; 4, antitragus; 5, con-cha ; 6, lobule. Fig. 203.—Outer sur-face of the BightPinna, showing itsmuscles. Fig. 204.—Inner sur-face of the BightPinna,
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