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.
The upper lateral cartilages (cartilagines laterales nasi) are situated in the upper part of the projecting portion of the nose, immediately below the free margin of the nasal bones. Each is flattened and triangular in shape, and presents one surface outwards, and the other inwards towards the nasal cavity. The anterior margin, thicker than the posterior one, meets the lateral cartilage of the opposite side above, but is closely united with the edge of the cartilage of the septum below; so closely indeed, that by some, as Henle, the upper lateral are regarded as reflected wings of the median cartilage. The inferior margin is connected by fibrous membrane with the lower lateral cartilage; and the posterior edge is inserted into the ascending process of the upper maxilla and the free margin of the nasal bone.
The lower lateral cartilages (cartilages of the aperture) are thinner than the preceding, below which they are placed, and are chiefly characterized by their peculiar curved form. Each consists of an elongated plate, so bent upon itself as to pass in front and on each side of the nostril to which it belongs, and by this arrangement serve to keep it open. The outer portion is somewhat oval and flattened, or irregularly convex externally. Behind, it is attached to the margin of the ascending process of the upper maxilla by tough fibrous membrane, in which are two or three cartilaginous nodules (cartilag. minores vel sesamoideae); above, it is fixed, also by fibrous membrane, to the upper lateral cartilage, and to the lower and fore part of the cartilage of the septum. Towards the middle line it is curved backwards, bounding a deep mesial groove, at the bottom of which it meets with its fellow of the opposite side, and continues to pass back- wards, forming a small part of the columna nasi, below the level of the cartilage of the septum. This inner part of the cartilage of the ala is thick and narrow, curls outwards, and ends in a free rounded margin, which projects outwards towards the nostril. The lower and most prominent portion of the ala of the nose, like the lobule of the ear, is formed of thickened skin with subjacent tissue, and is unsupported by cartilage.
The cartilage of the septum has a somewhat triangular outline, and is thicker at the edges than near the center. It is placed nearly vertically in the middle line of the nose, and completes, at the fore part, the separation between the nasal fossae. The anterior margin of the cartilage, thickest above, is firmly attached to the back of the nasal bones near their line of junction; and below this it lies successively between the upper and the lower lateral cartilages, united firmly with the former and loosely with the latter. The posterior margin is fixed to the lower and fore part of the central plate of the ethmoid bone; and the lower margin is received into the groove of the vomer, as well as into the median ridge between the superior maxillae.
This cartilage is the persistent anterior extremity of the primordial cranium. In young subjects it is prolonged back to the body of the pre-sphenoid bone; and in many adults an irregular thin band remains between the vomer and the central plate of the ethmoid.
From Quain's anatomy/