NOSE, AND THE. SENSE OF SMELL. 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 nasal, fossie, separated from one another by a vertical septum, and subdivided by spongy or turbinate(' bones projecting from the outer wall into three passages or meatuses, with which various cells or sinuses in the ethmoid, sphenoid, frontal, and superior maxillary bones commu nicate by narrow apertures.
The external portion of this organ may be described as a triangular pyramid which projects from the center of the face, immediately above the upper lip. Its summit or . root is connected with the forehead by means of a narrow bridge, formed on either side by the nasal bone and the nasal process of the superior maxillary bone. Its lower part presents two horizontal elliptical openings, the nostrils, which overhang the mouth, and are separated from one another by a vertical septum. The margins of the nostrils are usually provided with a number of stiff hairs (vibrimcs), which project across the open ings, and serve to arrest the passage of foreign substances, such as dust, small insects, etc., which might otherwise be drawn up with current of air intended for respiration. The skeleton, or framework of the nose, is partly composed of the bones forming the top and sides of the bridge and partly of cartilages, there being on either side an upper lateral and a lower lateral cartilage, to the latter of which are attached three or four small cartilaginous plates, termed sesamoid cartilages; there is also the cartilage of the septum which separates the nostrils, and in association posteriorly with the perpendicular plate of the ethmoid, and with the vomer, form's a complete partition between the right and left nasal fosses. It is the lower lateral, termed by sonic Writers the alar cartilage, which by its flexibility and curved shape forms the dilatable chamber just within the nostril. The nasal cartilages are capable of being slightly moved, and the nostrils of being dilated or contracted by various small muscles, which it is unnecessary to describe. The integument of the nose is studded with the openings of sebaceous follicles, which are extremely large and abundant in this region. The oleaginous secretion ol' these follicles often becomes of a dark color near the surface; and hence the spotted appear ance which the tip and lower parts of the sides, or Ow, of the nose frequently present. On firmly compressing or pinching the skin of these parts, the inspissated secretion is forced out of the follicles in the form of minute white worms with black heads.
The nasal foam, which constitute the internal part of the nose, are lofty, and of con siderable depth. They open in front by the nostrils, and behind they terminate by a vertical slit on either side in the upper part of the pharynx, above the soft palate, and and near the orifices of the eustachian tubes, which proceed to the tympanic cavity of the ear.
The mucuous membrane lining the nose and its cavities is called 'pituitary [Lat. pituita, rheum), from the nature of its secretion; or Schneiderian, from Schneider, the first anatomist who showed that the secretion proceeded from the mucous membrane, and not, as was previously imagined, from the brain; it is continuous with the skin of the face at the nostrils, with the mucous covering of the eye through the lachrymal duct (see EYE), and with that of the pharynx and middle ear posteriorly. This membrane varies in its structure in different parts of the organ. On the septum and spongy bones bounding the direct passage from the nostrils to the throat, the lining membrane is com paratively thick, .partly iu consequence of a multitude of glands 'being disseminated beneath it, and opening upon it, but chiefly, perhaps, from the presence of ample and capacious submucous plexuses of both arteries and veins, of which the latter are by far the more large and tortuous. These plexuses, lying as they do in a rec.-ion exposed more than any other to external cooling influences, appear to be designed to promote the warmth of the part, and to elevate the temperature of the air on its passage to the lungs. They also serve to explain the tendency to hemorrhage from the nose in cases of general or local plethora. In the vicinity of the nostrils, the mucous membrane exhibits papilhe and a scaly epithelium, like the corresponding parts of the skin, In the sinuses, and in all the lower region of the nose, the epithelium is of 'extreme delicacy, being of the columnar variety, and clothed with cilia. In the upper third of the nose—which, as the proper seat of the sense of smell, may be termed the olfactory region—the epithelium ceases to be ciliated, assumes a more or less rich sienna-brown tint, and increases remark ably in thickness, so that it forms an opaque soft upon the surface. It is com posed of an aggregation of nucleated particles, of nearly uniform appearance throughout, except that the lowest ones are of a darker color than the rest, from their containing a brown pigment in their interior. Dr. Todd and Mr. Bowman remark, in their Physio logical Anatomy, from which we have condensed the above account of the nasal mucous membrane, that the olfactory region abounds in glands, apparently identical with sweat glands, which dip down in the recesses of the submucous tissue among the ramifications of the olfactory nerve.