NASAL FOSSAE. 493 



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 contin- 

 uous 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 vibrissee. 



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 

 ophthalmic. 



NASAL FOSS&. 



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

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

 middle line. 



The Nasal fossae are two irregular, compressed cavities, extending 

 backwards from the nose to the pharynx. They are bounded supe- 

 riorly by the lateral cartilage 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 fibre-cartilaginous 

 septum. A plan of the boundaries of the nasal fossae will be found at 

 page 62. 



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

 projecting 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 its 

 surface by their prominence and by their convoluted form. The space 

 intervening 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 fossae : 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. 



The Mucous membrane of the nasal fossae is called pituitary, or 

 Schneiderian* The former name being derived from its secretion, 



* Conrad Victor Schneider, professor of Medicine at Wittenberg. His work, 

 entitled De Catarrhis, &c. was published in l66l. 



