Identifier: textbookofphysio1916howe (find matches)
Title: A text-book of physiology : for medical students and physicians
Year: 1916 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology Medicine
Publisher: Philadelphia and London : W. B. Saunders Company
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

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wenty—short,stiff hairs. The hair cells are arranged in four to six rows, onerow on the inner side of the inner rods of Corti and three to five * The most complete details of the structure of the ear will be found inthe great work of Retzius, De Gehororgan der Wirbelthiere, vol. ii, 1884,Stockholm. EAR AS AN ORGAN FOR SOUND SENSATIONS. 393 rows, according to the part of the cochlea examined on the outerside of the rods of Corti. Their total number has been estimateddifferently by different observers; but, accepting the lower figuresgiven, it may be said that there are at least 3500 inner hair cellsand 13,000 outer ones, giving a total of 16,500 or more. The theoryusually proposed to account for the mechanism by which the vibra-tions of the perilymph affect these cells, and especially the expla-nation of the means by which different sounds affect different cells,is that there is contained in the cochlea a mechanism which actsby sympathetic resonance. To make this theory clear a short
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Fig. 172.—Diagrammatic view of the organ of Corti, the sense cells, and the accessorystructures of the membranous cochlea (Testui): A, Inner rods of Corti; B, outer rodsof Corti ; C, tunnel of Corti ; D, basilar membrane; E, single row of inner hair (sense)cells; 6, 6, 6, rows of outer hair (sense) cells; 7, 7, supporting cells of Deiters. Theends of the inner hair cells are seen projecting through the openings of the reticulatemembrane. The terminal arborizations of the cochlear nerve fibers end around theinner and outer hair cells. description must be given of the nature of sound waves and thephysical facts in regard to sympathetic resonance. The Nature and Action of Sound Waves.—Sound waves inair consist of longitudinal vibrations of the air molecules, alternatephases of rarefaction and condensation. For convenience sake,these waves are usually represented graphically after the manner ofwater waves, by a curved line rising above and falling below amedian zero line, the ordinate

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