The inner wall of each cavity of the nose is formed by the septum, a median partition composed of the perpendicular plate of the ethmoid bone, and the vomer, whose edges cor respond to ridges formed at the median sutures of the nasal,superior maxillary, and palate bones, and on the inferior surfaces of the frontal and sphenoid bones. The septum is not commonly ' quite vertical : it may lean to either side, or I may be curved slightly in both directions, or mav be convex on both sides and have a cavity e .
In its interior. Each of its sides exhibits at the upper and back part the grooves of SOMQ of the olfactory neries, becoming more shallow as they descend ; and in various parts it is slightly niarked by the passage of bloodvessels and other nerves.
Thus, the bones which form the proper cavities of the nose are fourteen ; viz.—the two nasal, two superior maxillary, two palatine, the two inferior, and two sphenoidal turbinated, bones,the frouta I ,ethmoid, sphenoid, and vomer. And, with the space which these enclose, many adjacent cavities communicate ; The frontal sinuses, which open through the ant& rior ethmoid cells and infundibulum into the, middle meatus. 2. The anterior ethmoid cells, which open by the same canal or by separate apertures, into the same meatus. 3. The pos terior ethmoidal cells, which open into the superior meatus. 4. The sphenoidal sinuses, which open through the posterior part of the roof of the nose behind the same meatus : and 5. The antrum, which opens into the middle meatus.
The osseous parts hitherto described form the skeleton of the interior of the nose, but con tribute little to the formation of its external prominent part. Of this part the osseous ske leton is eornposed of the two nasal bones, and the nasal or ascending processes of the superior maxillary bones, which together form the bridge of the nose and a small portion of its lateral walls. Each na.sal bone is elongated, quadri lateral, and narrower above than below. Its anterior surface is convex from side to side, and either presents a double curve from above down wards, or is slightly concave in its whole length. The two together form a prominent arch above aud in front of the anterior aperture of the nose : their surface is continued outwards and down wards over the ascending processes of the supe rior maxillary bones, is smooth, and is marked only by small apertures giving passage to blood vessels and nerves.
The internal edges of the nasal bones are united in the median line by a straight suture, the continuation of the sagittaLsuture. In front
their union is smooth; but behind and above, where the bones are much thiqer than they are below, a deep ridge or crest is fonned which is received into that part of the septum of the nose which is fonned by the nasal spine of the frontal bone, and the vertical plate of the ethmoid. Sometimes, however, these margins, instead of forming a ridg,e, are separate, and en close a groove in which the edge of the septum is received. The superior thick borders of the nasal bones articulate by a serrated suture with the notch and the nasal spine of the frontal bone; and this suture, which forms part of the great transverse suture, is continued into that uniting the nasal proceises of the superior maxillary bones with the internal angular pro cesses of the frontal. The outer and largest margin of the nasal bone articulates with the nasal process of the superior maxillary, and is slightly overlapped by its sharp edge. The lower free margin is sharp and uneven.
The median suture of the nasal bones, and the short portion of the sagittal suture imnie diately above it, are the parts of the median suture of the skull which remain longest un ossified : in ordinary cases, indeed, they do not close even in the latest periods of life. This, in some measure, distinguishes man from the other quadrumana : in the Chimpanse, the nasal bone is single ; in the Orang, also, it usually is so; and in the adult Siamang (whose skull approaches nearest in form to that of man) and other Gibbons, the nasal bones are always united.* But a more distinctive character is the tteadth and shortness of these bones in man, and the elevation of their inner borders, on which the projection of the upper part of the bridge of the nose depends; a projection in which the nose of the lowest negro surpasses that of either the Chimpanse or the Siamang.
The structure ql the bones of the nose pre sents little that is peculiar. The thin lamellw of the ethmoidal cells, the turbinated bones, and others of similar structure, receive their mate rials of nutrition entirely from the bloodvessels of tbe Schneiderian membrane. They contain no vascular canals within their own substance. Their corpuscles and minute canals which pro ceed from them are larger than those of average size : the former are very numerous and closely set, and the latter ramify in all directions ; arrangements which seem to be adapted to the combination of the least possible weight with the necessary firmness of support.