. Kirkes' handbook of physiology . Fig. 428.—Bipolar OlfactoryCells from the Nasal Fossae ofthe Rat (Full-term Fetus). A,Epithelium of the olfactorymucosa; e, epithelial cells; f, f,nerve cells; i, nerve fibers ter-minating freely on the epithelialsurface; h, olfactory nerve fibers;g, sensory nerve derived from thetrigeminus. (Cajal.) 612 THE SENSES The Stimulation of the Olfactory Membrane. The extent of thenasal mucous surfaces, and of the frontal and antral sinuses connected withthem, might suggest that the sensory olfactory surface is widely distributed,but such is not the case. Air impreg
. Kirkes' handbook of physiology . Fig. 428.—Bipolar OlfactoryCells from the Nasal Fossae ofthe Rat (Full-term Fetus). A,Epithelium of the olfactorymucosa; e, epithelial cells; f, f,nerve cells; i, nerve fibers ter-minating freely on the epithelialsurface; h, olfactory nerve fibers;g, sensory nerve derived from thetrigeminus. (Cajal.) 612 THE SENSES The Stimulation of the Olfactory Membrane. The extent of thenasal mucous surfaces, and of the frontal and antral sinuses connected withthem, might suggest that the sensory olfactory surface is widely distributed,but such is not the case. Air impregnated with vapor of camphor has beeninjected into the frontal sinus through a fistulous opening, and odorous sub-stances have been injected into the antrum of Highmore; but in neither casewas any odor perceived by the patient. All parts of the nasal cavities areendowed with cutaneous sensibility by the nasal branches of the first and. Fig. 429.—Principal Constituent Elements of the Olfactory Bulb of a Mammal. (Van Gehuch- ten.) second divisions of the fifth nerve, hence the sensations of cold, heat, itching,tickling, and pain, and the sensation of tension or pressure in the these nerves cannot perform the functions of the olfactory nerves isproved by cases in which the sense of smell is lost, while the mucous mem-brane of the nose remains susceptible to the various modifications of thesense of touch. But it is often difficult to distinguish the sensation of smellfrom that of mere feeling, and to ascertain what belongs to each is true particularly of the sensations excited by acrid vapors in the nose,as of ammonia, horse-radish, mustard, etc., and the difficulty is the greaterwhen it is remembered that these acrid vapors have nearly the same actionupon the mucous membrane of the eyelids. THE STIMULATION OF THE OLFACTORY MEMBRANE 613 The true olfactory membrane is limited to the small
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