File:Anatomy, physiology and hygiene (1900) (14756274196).jpg

Identifier: anatomyphysiolog00walk (find matches)
Title: Anatomy, physiology and hygiene
Year: 1900 (1900s)
Authors: Walker, Jerome, 1845-
Subjects: Physiology Health
Publisher: Boston, Allyn and Bacon
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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he sense of smell, supplies offood stored in the ice long distances away. By this senseanimals also detect the presence of pursuers, if the latterapproach from the windward side. 352. The essential organ of smell is the upper half ofthe mucous membrane of the nasal fossae, or nose cavi-ties.1 These are separated from each other by a verti- 1 The lower part of each nasal cavity is the respiratory part; its epi-thelium, like that of the trachea, consists of ciliated cells. The upperportion is the olfactory part; it has no ciliated cells, but has many rod-shaped cells, in which the filaments of the olfactory nerves end. THE SENSES: TOUCH, TASTE, AND SMELL. 323 cal wall of cartilage and bone, called the septum. In themucous membrane which covers part of the septum andon the two upper turbinated bones are distributed theterminal filaments of the olfactory nerve, or nerve of smell.These filaments come through the roof of the fossae, asthrough a sieve, from the olfactory bulbs, which are the
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Fig. 102. Left Nasal Cavity. 1, left olfactory bulb with its nerve branches. 2, the nasal nerve. 3, a gang-lion, and nerves of the sympathetic nervous system. terminations of the olfactory nerves. These bulbs lieunder the anterior portion of the cerebrum and upon thebony floor of the cranial cavity (Fig. 102). The lowerhalf of the mucous membrane of the nose is supplied withordinary sensibility by a nasal branch o( the fifth pair ofcranial nerves. Its irritation causes sneezing. 353. Odors, to be recognized, must be presented in agaseous or vaporous form to the mucous membrane con-taining the olfactory nerve filaments. The most minute 324 SENSATIONS. portion of such a substance as musk will be readily per-ceived, if it be forcibly drawn up during inspiration intothe higher portions of the nasal fossae. Some persons areso susceptible to odors and emanations that the smell ofcertain substances — of roses, for example, or of new-mownhay, or of certain drugs in a powdered state — may

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