Nose

(nōz) (From A.S. nese.] (Physiol.) The nose is not only the organ of smell, but is likewise a part of the apparatus of respiration and voice. Considered anatomically, it may be divided into an external part the projecting portion, to which the term nose is popularly restricted; and an internal part, consisting of two chief cavities, or nu sal fo e, separated from one another by a vertical septum, and subdivided by spongy or turbinated bones projecting from the outer wall into three pa ages or meat uses, with which various cells or sinuses in the ethmoid, sphenoid, frontal, and superior maxillary bones communicate by narrow apertures. The meat uses are lined by a mucous membrane, called the pituitary, or Schneiderian, from Schneider, who first showed that the secretion of the nasal fo æ procoeded from the mucous membrane, and not from the brain. Upon the mucous membrane of the nasal pa ages, the olfactory nerve ramifies, and also ab ranch of the fifth pair of nerves. This membrane is of considerable extent in man; and in those animals whoso sense of smell is very acute, it is still more extensive. When substances are presented to the nose, the air that is pa ing through the nostrils brings the odoriferons particles of matter in contact with the filaments of the olfactory nerves, that are spread upon the membrane which lines the air-pa ages, and the impre ion is then transmitted to the brain. The nature of odorous emanations is so little known, that it is impo ible to give a definite account of the mode in which they produce sensory impre ions. From the fact that most odorous substances are volatile, and vice vers a, it may be presumed that they consist of particles of extreme minutene di olved in the air; yet the most delicato experiments have failed to discover any lo of weight in musk, and other strongly odorous substances, after they have been freely evolving their effluvia for several years. But whatever may be the. nature of the odorous matter, it is nece ary that it should be transmitted by a respiratory current through the nostrils to the true olfactory region, whose membrane must be in a healthy condition. If it is too dry, or if there is an inordinate excretion of fluid from its surface(both of which conditions occur in catarrh or cold in the head), smell is impaired or lost. The sense of smell is more acute in many of the lower animals (dogs, for example,) than in man, and they employ it in guiding them to their food, in warning them of approaching danger, and other purposes. To civilized man its utility is comparatively small; but it is occasionally much increased when other senses are deficient. [s. 652]