Nose, the organ of the sense of smell in vertebrated animals, and in the three highest, classes connected with the respiratory function. Of the 14 bones which enter into the composition of the cavities of the nose in man, the principal are the nasal, attached more or less perpendicularly to the frontal bone above and to the superior maxillary on the sides; in the lower orders these bones become more horizontal and more developed, as the face and animal propensities predominate over the cranium and the intellect. The nasal cavities, bounded in front by these bones, and separated into two by the vomer, open widely anteriorly to the external air and posteriorly into the pharynx; the upper wall is pierced by numerous foramina, through which enter the filaments of the olfactory nerve, or nerve of smell; the lower wall forms the bony roof of the mouth, and is nearly horizontal; the outer wall is divided into the superior, middle, and inferior meatuses by the turbinated bones, into the first of which open the posterior ethmoidal and sphenoidal sinuses, into the second (much larger) the frontal and anterior ethmoidal sinuses and the great cavity of the antrum, and into the third the duct of the nasal canal which conveys the tears from the eyes to the nose; from the last also the Eustachian tube, by which the tympanic cavity of the ear communicates with the throat, may be most easily entered, as is frequently necessary in aural surgery; the septum or inner wall is a thin vertical partition situated upon the median line, and separating the nasal passages on the right side from those on the left.
The suture of the nasal bones in man remains ununited generally until very late in life, in this differing from the condition in the highest apes, in which they are very early consolidated into a single bone with hardly a trace of suture; their inner border is also elevated, so that the depressed nose of the negro has never the flatness of that of the gorilla and chimpanzee. The external prominent part of the nose, which gives the character to the feature, is composed of several cartilages, connected to the bones and to each other by strong fibrous tissue, sufficiently firm to preserve the shape of the organ, and so elastic and flexible as to permit the expansion and contraction of the nostrils in respiration; at the tip of most noses, on the median line, may be felt a fossa or depression bounded on each side by the lateral cartilages, which, with the absence of rigidity, some ethnologists have made characteristic of certain human races, like the Malay and negro. The varying expression given to the face by the movements of the nose depends on the action of its muscles, attached to the cartilages, skin, and upper lip; most of the expressions arising from these movements are disagreeable, indicating either contempt, anger, fear, or pain.
The openings of the nose are provided with stiff curved hairs, which prevent the entrance of many particles floating in the air. The mucous membrane lining the nasal passages is of two kinds, viz.: the Schnei-derian membrane, occupying the lower portion, and the olfactory membrane, occupying the upper portion. The Schneiderian membrane is covered with ciliated epithelium, is provided with compound mucous glandules, and supplied with nerves of ordinary sensibility from the nasal branch of the ophthalmic division of the fifth pair; it is to be considered as forming a part of the respiratory surfaces. The olfactory membrane is covered with non-ciliated epithelium, provided with simple, nearly straight mucous follicles, and supplied with filaments from the olfactory nerve; it constitutes the organ of the special sense of smell. The soft olfactory nerves or nerves of smell arise from the olfactory lobules, which rest, in the interior of the cranium, upon the cribriform plate of the ethmoid bone; the nerves then pierce the ethmoid bone and reach the nasal cavities, being finally distributed to the olfactory mem-brane upon the upper part of the septum, and upon the superior and middle turbinated bones. - The nose forms one of the characteristic features of the human face, and by physiognomists has been regarded as a faithful index of character.
The sense of smell is less developed than that of sight in man, and in comparison with that of some other animals is very feeble, and the more so in proportion to the elevation of the race in the scale of civilization; the blind have a more acute sense of smell to compensate for the deficiency of sight; the Mongolian, the negro, and the American Indian have a greater development of the internal cavities of the nose than the white races. In man the nose projects beyond the level of the upper jaw, the opening of the nostrils being horizontal and downward; but even in the highest apes this feature is flat, and the nasal orifice vertical and forward. The ethnological characters derived from the shape of the nose are given in the articles on the different races, and in Ethnology. In fishes, breathing by gills, there is no communication between the nose and the mouth or throat, except in the myxi-noids; in batrachians and reptiles, all of which in the adult state breathe more or less by lungs, the nose and mouth communicate, by a short passage as in the frog, or by a long one as in the crocodile; in birds the nostrils open on the back of the bill, generally nearest the base, and are frequently covered by bristly feathers to prevent the entrance of foreign bodies, and they communicate with the mouth behind.
In mammals only are found the sinuses and cellular cavities in the frontal, sphenoid, ethmoid, and superior maxillary bones, larger in some than in others; the nasal cartilages are often widely different from those of man, as may be seen in the movable snout of the mole and hog, and in the proboscis of the tapir and elephant, which are only modified and largely developed noses; in cetaceans the nasal openings are on the top of the head, constituting the blow-holes. - There are many congenital defects in which the nose is concerned. It may be almost entirely deficient, partially developed, closed in front, or fissured below; the septum may be distorted or absent; or the organ may be monstrously developed. The skin of the nose is subject to cutaneous eruptions; the numerous small veins may be dilated, giving a red color to the tip, which, from the disturbance and retardation of a naturally slow circulation, is very difficult to remove. In common colds the mucous membrane is gorged with blood, and often so thickened as to interfere with respiration through the nose, and even to close the posterior passage to the throat. Abscesses, chronic thickening, deep ulcerations, ozaena, lupus, polypus, and cancer are common in this organ, and can only be alluded to here.
Fig. 1. - Olfactory Membrane of the Sheep, in vertical section. ". Epithelium, b, b. Fibres of the olfactory nerve, c. Mucous follicle, d. Orifice of the mucous follicle.
Fig. 2. - Profile View of the Nasal Passages. a. Superior turbinated bone, covered by its mucous membrane, b. Middle do. c. Inferior do. d. Horizontal or hard palate.
Fig. 3. - Transverse Section of the Nasal Passages. Cr. Cribriform plate of the ethmoid bone, upon which rest the olfactory lobules and through which pass the filaments of the olfactory nerves. S. T. Superior turbinated bone. M. T. Middle turbinated bone. /. T. Inferior turbinated bone. An. Antrum of the superior maxillary bone. Sp. Septum of the nares. PL Hard palate.