Vessels of the nose.—Its art9ries are derived from the ophthalmic, the internal maxillary, and the facial. The ophthalmic artery g,ives it the anterior ethmoidal, which enters with the ethmoidal nerve, the posterior ethmoidal, and the nasal, which anastomoses near the angle of the eye with the angular branch of the facial artery. From the internal maxillary trunk the nose and the adjacent cavities are supplied through many branches, namely, the alveolar, which sends branches into the antrum, the infra-or bitar of which the terminal branches partly supPly the skin, the Vidian, anterior palatine, pterygo-palatine, and spheno-palatine, each of which, as it passes towards or through the canal after which it is named, sends branches to the mucous membrane of the adjacent part of the nose or of the cavities opening into it. From the facial artery branches are derived both through the superior labial and from the trunk itself. Indeed, the dorsal arteries of the nose may generally be regarded as the termination of the facial artery, for they are usually larger than the angular artery, which is given off as a branch from one of them. They chiefly supply the skin and muscles; they form a complete network nver the nose, and those of one side anastomose freely in the middle line with those of the other. Many of their branches also pass between the cartilages or turn in at the nostrils and supply the anterior part of the mucous membrane.
The veins of the nose, so far as they are known, are associated with its arteries. Their communication with the veins within the skull has been already mentioned. The anastomosis is chiefly effected by means of the branches of the ethmoidal and splicno-palatine veins, which communicate with branches opening into the longitudinal and coronary sinuses.
The lymphatic vessels of the nose have not been particularly examined. Cloquet says their principal trunks accompany the blood vessels and go to the jugular ganglia.
Developement of the nose.—The develope ment of the nasal cavities lays, as it were, the foundation for the construction of the face.* They are first formed as a kind of canal, whose lateral walls are chiefly composed by the ante rior and lateral frontal processes of Reichert— those processes which grow out from the sides of the covering of the first cerebral vesicle ( Stirnkappe), in front of the first visceral arch. This canal has on its outer side and behind it the rudimental substance for the upper jaws, (the superior maxillary processes of lteichert,) and above it the base of the skull and the origins of the first pair of visceral arches thence arising. As the upper jaws grow with a rapi dity far exceeding that of the growth of the frontal processes, they come at last to form alone the lateral walls of this canal, while the frontal processes form its inner walls ; and, together with those changes, the canal becomes deeper, and its external apertures, which at first lay at the sides of the head between the two frontal processes of each side, approach the median line, and assume a lower position. After this, as the upper jaw of each side, con tinuing to grow inwards, approaches that of the opposite side, they at length unite to form the palate, and thus separate the common ca vity, which at first existed, into an oral and a nasal cavity.
Of the parts just mentioned, the anterior frontal process is reg-arded by Reichert as the basis in which the nasal bone is developed ; and the lateral frontal, or naso-frontal process as the basis for the lachrymal bone. The supe rior maxillary bone appears to be developed in the part named after it; the intermaxillary bone in a portion of the anterior frontal process, or its junction with the superior maxillary pro cess; the palate bone and the pterygoid pro cesses in the upper part of the first visceral arch.
The formation of the parts within the nasal cavities is, he says, thus effected : within the formative substance enclosed between the walls of the one rudimental cavity two cartilw4es form ; one of these is the prolonged cartila ginous body of the first ceplralic vertebra which forms the septum of the nasal cavities, and may be traced without any breach of continuity to their outer orifice, where it ends membranous in the adjacent formative mass. The other cartilaste is double, and appears somewhat later trian the preceding, on each side of which it lies close to the lower part of the tirst ce phalic vertebra, with an arched surface directed outwards to the eye. Each of these second, or lateral cartilages becomes the cellular portion of the ethmoid bone, the lamina papyraeea, and may be easilfseparated froin the vertebra and its visceral arch, from which its formation is entirely distinct. Even for some time after they are ossified this separation may be effected without injury to the surrounding parts; but at a later period they completely coalesce. The ossification of the septum takes place later than that of the other bones of the face. In all Illammalia it makes progress frorn the ba.se of the skull downwards and forwards, and in all a part of the septum in front and below is left unossified ; so that divisions are produced which had originally no existence. The vomer, Reichert thinks, is formed separately when the palatine portions of the superior maxillary bones meet together.
The olfactory nerve is originally, like the optic and auditory nerves, a kind of vesiculat. or tubular prolongation from the medullary tube which constitutes the cerebro.spinal axis of the embryo. According to Valentin,* it proceeds from the most anterior part of this ' tube, that is, from the foremost of the three embryonic cerebral vesicles; but, according to Reichert, from the lower arid front part of the side of the second of them. Von Baert found the olfactory nerves presenting this vesicular form in the chick during the third day of in cubation; they projected from the lower sada of each hemisphere into the formative tiss of the skull, and exhibited a small round lucid surface bordered by a dark circle. Ita observed similar appearances in the shee adder. The interior of the vesicle is according to Valentin, by a delicate epithelium. Anteriorly it appears to ter at the end of the olfactory bulb ; poster! is continuous with the anterior part of lateral ventricles of the cerebrum.