444 NASAL FOSSAE. 



behind, with the nasal processes of the superior maxillary bones ; and below 

 with the alar fibre-cartilages. 



Jllarfibro-cartilages. Each of these cartilages is curved in such a man- 

 ner as to correspond with the opening of the nostril, to which it forms a 

 kind of rim. The inner portion is loosely connected with the same part 

 of the opposite cartilage, so as to form the columna. It is expanded and 

 thickened at the point of the nose to constitute the lobe ; and on the side 

 forms a curve corresponding with the form of the ala. This curve is pro- 

 longed downwards and forwards in the direction of the posterior border 

 of the ala by three or four small fibro-cartilaginous plates, which are ap- 

 pendages of the alar fibre-cartilage. 



The whole of these fibro-cartilages are connected with each other and 

 to the bones, by perichondrium, which, from its membranous structure, 

 permits of the freedom of motion existing between them. 



5. The Mucous membrane, lining the interior of the nose, is continuous 

 with the skin externally, and with the pituitary membrane of the nasal 

 fossae within. Around the entrance of the nostrils it is provided with 

 numerous vibrissce. 



6. Vessels and Nerves. The Arteries of the nose are the lateralis nasi 

 from the facial, and the nasalis septi from the superior coronary. 



Its Nerves are, the facial, infra-orbital, and nasal branch of the oph- 

 thalmic. 



NASAL FOSSAE. 



To obtain a good view of the nasal fosste, the face must be divided 

 through the nose by a vertical incision, a little to one side of the middle 

 line. 



The Nasal fosses are two irregular compressed cavities, extending back- 

 wards from the nose to the pharynx. They are bounded superiorly by the 

 lateral cartilage of the nose, and by the nasal, sphenoid, and ethmoid 

 bones ; inferiorly by the hard palate ; and, in the middle line, they are 

 separated from each other by a bony and fibro-cartilaginous septum. A 

 plan of the boundaries of the nasal fossas will be found at page 91. 



Upon the outer wall of each fossa, in the dried skull, are three project- 

 ing processes, termed spongy bones. The two superior belong to the 

 ethmoid, the inferior is a separate bone. In the fresh fossae these are 

 covered with mucous membrane, and serve to increase the surface of that 

 membrane by their prominence and convoluted form. The space inter- 

 vening between the superior and middle spongy bone is the superior 

 meatus ; the space between the middle and inferior the middle meatus ; 

 and that between the inferior and the floor of the fossa the inferior 

 meatus. 



These meatuses are passages which extend from before backwards, and 

 it is in rushing through and amongst these that the atmosphere deposits 

 its odorant particles upon the mucous membrane. There are several 

 openings into the nasal fossaB: thus, in the superior meatus are the openings 

 of the sphenoidal and posterior ethmoidal cells ; in the middle the anterior 

 ethmoidal cells, the frontal sinuses, and the antrum maxillare ; and, in the 

 inferior meatus, the termination of the nasal duct. In the dried bone 

 there are two additional openings, the spheno-palatine and the anterior 

 palatine foramen ; the former being situated in the superior, and the latter 

 in the inferior meatus. 



