The nose is the special organ of the sense of smell. It has also other functions to fulfil; -for, communicating freely with the cavities of the mouth and lungs, it is concerned in respiration, voice, and taste ; and by means of muscles on its exterior, which are closely connected with the muscles of the face, it assists more or less in expression.
This organ consists of, first, the anterior prominent part, composed of bone and cartilages, with muscles already described, which slightly move the cartilages, and two orifices, anterior nares, opening downwards ; and, secondly, of the two nasal fossae, in which the olfactory nerves are expanded. The nasal fossae are separated from each other by a partition, septum nasi, formed of bone and cartilage: they communicate with hollows in the neighboring bones (ethmoid, sphenoid, frontal, and superior maxillary) ; and they open backwards into the pharynx through the posterior nares. The skin of the nose is studded, particularly in the grooves of the alae or outer walls of the nostrils, with numerous small openings, which lead to sebaceous follicles. Within the margin of the nostrils there is a number of short, stiff, and slightly curved hairs - vibrissae - which grow from the inner surface of the alae and septum nasi.
The pituitary or Schneiderian membrane, which lines the cavities of the nose, is a highly vascular mucous membrane, inseparably united, like that investing the cavity of the tympanum, with the periosteum and perichondrium, over which it lies. It is continuous with the skin through the nostrils; with the mucous membrane of the pharynx through the posterior apertures of the nasal fossae; with the conjunctiva through the nasal duct and lachrymal canaliculi; and with the lining membrane of the several sinuses which communicate with the nasal fossae.
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These are the chief support of the outer part of the organ. They occupy the triangular opening seen in front of the nasal cavity in the dried skull, and assist in forming the septum between the nasal fossae. There are usually reckoned two large and three small cartilages on each side, and one central piece or cartilage of the septum.
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The nasal fossae, and the various openings into them, with the posterior nares, have been previously described as they exist in the skeleton, and the greater part of that description is also applicable generally to the nose in a recent state; but it is proper to mention certain differences in the form and dimension of parts, which depend on the arrangement of the lining membrane, viz.
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