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There may be recognized in the nose a base, which is directed downward, and a root, situated between the two orbits; the rounded anterior surface is directed forward and upward and is termed the dorsum, and it terminates in the tip of the nose, or apex nasi. The margins representing the lower borders of the base pass backward from the tip to form the alee, and they constitute the lateral boundaries of the nostrils (nares), which are separated from each other by the antero-inferior portion of the nasal septum, the membranous septum.

 

The skeleton of the nose is formed partly by bones and partly by cartilages, the latter consisting of the single cartilaginous septum, the anterior continuation of the bony nasal septum, and of a series of paired cartilages.

The cartilaginous nasal septum

The cartilaginous nasal septum is a rather thin, rarely quite even, irregularly quadrilateral plate which is attached to the anterior margin of the vomer and the inferior margin of the perpendicular plate of the ethmoid. Inferiorly it does not quite reach to the nostrils, but terminates above them by a free margin which is indicated by a shallow groove on the mucous membrane, so that a small portion of the nasal septum is membranous, and is known as the membranous or mobile septum. The nasal septum is usually somewhat bent toward one side and this deviation is frequently very pronounced. The mobile septum nevertheless contains the inner crura of both greater alar cartilages. The cartilaginous septum frequently sends a process between the vomer and the perpendicular plate of the ethmoid ; this process is termed the sphenoidal process of the cartilaginous septum and occasionally extends as far as the body of the sphenoid bone.

The lateral nasal cartilages

The lateral nasal cartilages seem to be the direct continuation of the cartilaginous septum, since upon the dorsum of the nose they are fused not only with each other, but also with the upper portion of the anterior margin of the septum. They are flat triangular plates forming the anteroinferior portion of the lateral nasal wall, and are fixed by connective tissue to the anterior margins of the nasal bones and nasal processes of the maxillae. Inferiorly they do not extend to the nostrils, but are loosely connected with the cartilages of the alae of the nose.

The greater alar cartilages

The greater alar cartilages are two cartilaginous strips which are curved around the anterior ends of the nostrils; each is composed of an inner and an outer cms, which are continuous with each other at the tip of the nose. The outer crus is much wider than the inner, is applied to the lower extremity of the lateral cartilage, and follows the upper border of the ala of the nose, forming its anterior portion and also the tip of the nose. The much narrower inner crus is situated in the membranous septum at the lower margin of the cartilaginous septum, with which it is loosely connected. Both inner crura are in contact in the median line.

The lesser alar cartilages

The lesser alar cartilages are rather constant small cartilages which are frequently double, and are placed above and behind the posterior extremity of the outer crura of the greater alar cartilages.

The sesamoid nasal cartilages are frequent but inconstant constituents of the dorsum and are situated between the two greater alar cartilages (outer crura) and the lower extremities of the lateral cartilages. In addition to these, the nasal skeleton also includes other smaller cartilages which are of rarer occurrence.

The nose possesses muscles as well as cartilages. The skin, particularly at the alae, is rich in large sebaceous glands; it is very thin and delicate and contains practically no fat, and is firmly adherent to the underlying tissues in the region of the cartilaginous skeleton.

 

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