. Animal physiology. Physiology, Comparative; Physiology, Comparative. CONFORMATION OF THE NOSE. 383 506. The most advantageous position of this organ is evi- dently at the commencement of the respiratory passages; so that the air, which is being received into the lungs, may pass through it, and be tested, as it were, by its peculiar sensibility. In all the air-breathing Yertebrata we find a pair of cavities, the nasal fossae, which are situated between the mouth and the orbits. They possess two orifices,—the anterior nares, or nostrils, usually opening upon the front of the face,—and the post
. Animal physiology. Physiology, Comparative; Physiology, Comparative. CONFORMATION OF THE NOSE. 383 506. The most advantageous position of this organ is evi- dently at the commencement of the respiratory passages; so that the air, which is being received into the lungs, may pass through it, and be tested, as it were, by its peculiar sensibility. In all the air-breathing Yertebrata we find a pair of cavities, the nasal fossae, which are situated between the mouth and the orbits. They possess two orifices,—the anterior nares, or nostrils, usually opening upon the front of the face,—and the posterior nares, which open into the pharynx. The two cavities are separated from each other by a vertical partition, which passes backwards and forwards on the middle line ; their sides are formed by the various bones of the face, and by the cartilages of the nose ; their extent is very considerable, es- pecially in animals that have a prolonged muzzle. The interior of these cavities is lined by a deli- cate mucous membrane, on which the olfactory nerves are distri- buted ; and the extent of this is increased, by its being folded over certain projections from the walls of the cavity, which are termed spongy bones. Of these there are three in Man. Prolongations of this membrane are carried also into cavities hollowed out in the neighbouring bones, which are termed sinuses. Thus we have the frontal sinuses, I, situated just above the nose, between the eyebrows ; and the sphenoidal sinuses, m, situated further back. There is also a large cavity hollowed out in the bone of the upper jaw on either side. The membrane which lines these is kept moist by its own secretion ; and it is covered with vibratile cilia, the office of which seems to be, to prevent that secretion from unduly accumulating, by conveying it over the surface of the membrane to the outlet. 507. The mechanism of the sense of Smell is very simple; DD 2. -Vertical Section of the Nasal Cavity. a, mouth; b, nostril; c, p
Size: 1568px × 1593px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarpenterwilliambenja, bookcentury1800, bookdecade1840
