NASAL FOSSAE. 679 



The integument covering the dorsum and sides of the nose is thin, and loosely 

 connected with the subjacent parts; but where it forms the tip or lobe, and the 

 alse of the nose, it is thicker and more firmly adherent. It is furnished with a 

 large number of sebaceous follicles, the orifices of which are usually very dis- 

 tinct. 



The mucous membrane, lining the interior of the nose, is continuous with the 

 skin externally, and with that which lines the nasal fossse within. 



The arteries of the nose are the lateralis nasi, from the facial, and the nasal 

 artery of the septum, from the superior coronary, which supplies the alse and 

 septum ; the sides and dorsum being supplied from the nasal branch of the oph- 

 thalmic and the infraorbital, 



The veins of the nose terminate in the facial and ophthalmic. 



The nerves of the nose are branches from the facial, infraorbital, and infra- 

 trochlear, and a filament from the nasal branch of the ophthalmic. 



NASAL FOSS.E. 



The Nasal Fossae are two irregular cavities, situated in the middle of the face 

 and extending from before backwards. They open in front by the two anterior 

 nares, and terminate in the pharynx, behind by the posterior nares. The boun- 

 daries of these cavities, and the openings which are connected with them, as they 

 exist in the skeleton, have been already described (pp. 187-189). 



The mucous membrane lining the nasal fossae is called pituitary, from the 

 nature of its secretion ; or Schneiderian, from Schneider, the first anatomist who 

 showed that the secretion proceeded from the mucous membrane, and not, as was 

 formerly imagined, from the brain. It is intimately adherent to the periosteum, 

 or perichondrium, over which it lies. It is continuous externally with the skin, 

 through the anterior nares, and with the mucous membrane of the pharynx, 

 through the posterior nares. From the nasal fossee its continuity may be traced 

 with the conjunctiva, through the nasal duct and lachrymal canals; with the 

 lining membrane of the tympanum and mastoid cells, through the Eustachian 

 tube ; and with the frontal, ethmoidal, and sphenoidal sinuses, and the antrum 

 maxillare, through the several openings in the meatuses. The mucous mem- 

 brane is thickest, and most vascular, over the turbinated bones. It is also thick 

 over the septum ; but, in the intervals between the spongy bones, and on the 

 floor of the nasal fossa, it is very thin. Where it lines the various sinuses and 

 the antrum maxillare, it is thin and pale. 



The surface of the membrane is covered with a layer of tessellated epithelium, 

 at the upper part of the nasal fossae, corresponding with the distribution of the 

 olfactory nerve, but is ciliated throughout the rest of its extent, excepting near 

 the aperture of the nares. 



This membrane is also provided with a nearly continuous layer of branched 

 mucous glands, the ducts of which open upon its surface. They are most nume- 

 rous at the middle and back parts of the nasal fossae, and largest at the lower 

 and back part of the septum. 



Owing to the great thickness of this membrane, the nasal fossae are much nar- 

 rower, and the turbinated bones, especially the lower ones, appear larger, and 

 more prominent, than in the skeleton. From the same circumstance, also, the 

 various apertures communicating with the meatuses are either narrowed or 

 completely closed. 



In the superior meatus, the aperture of communication with the posterior 

 ethmoidal cells is considerably diminished in size, and the spheno-palatine fora- 

 men completely covered in. 



In the middle meatus, the opening of the infundibulum is partially hidden by 

 a projecting fold of mucous membrane, and the orifice of the antrum is con- 

 tracted to a small circular aperture, much narrower than in the skeleton. 



In the inferior meatus, the orifice of the nasal duct is partially hidden by either 



