MUCOUS MEMBEAKB OF THE XOSE. 



775 



and sahenoidal sinuses, and in the ethmoidal cells, the mucous lining mem- 

 brane, being very thin and pale, contrasts strongly with that which occupies 

 the nasal fossae. 



Fig. 533. OUTER WALL OF THE LEFT NASAL FOSSA, COVERED BY TUB PITUITARY 

 MEMBRANE (from Arnold), f 



1, frontal bone ; 2, left nasal bone ; 3, superior maxillary ; 4, body of the sphenoid with 

 the sphenoidal sinus ; 5, projection of the membrane covering the upper spongy bone ; 6, 

 that of the middle ; 7, that of the lower ; the upper, middle, and lower meatuses are seen 

 below the corresponding spongy bones; 8, opening of the Eustachian tube ; 9, depression 

 of the lining membrane of the nose in the anterior palatine canal. 



In respect of the characters of the mucous membrane, three regions of 

 the nasal fossae may be distinguished. Thus, the region of the nostrils, 

 including all the part which is roofed by the nasal cartilages, is lined with 

 stratified squamous epithelium ; the remainder of the fossae is divisible 

 into two parts, viz. , the olfactory region in which the epithelium is non-ci- 



Fig. 534. 



Fig. 534. VERTICAL SECTION OF A SMALL PORTION op 

 THE MEMBRANE OF THE NOSE FROM THE OLFACTORY 

 HKGION (from Ecker), ^ 



a, coloured part of the epithelium ; a', nuclei ; 5, 

 deeper part containing the olfactory cells and fila- 

 ments ; c, connective tissue of the mucous membrane ; 

 d, one of the mucous glands : d', its duct; e, twig of 

 the olfactory nerve ; c', small twig passing to the 

 surface. 



liated and columnar, and the respiratory 

 region in which it is ciliated and columnar. 

 The membrane in the respiratory part, con- 

 sisting of the inferior turbinated and all the 

 lower portions of the fossae, is studded with nu- 

 merous mucous glands, which are of branched acinated appearance, and open 

 by apparent orifices on the surface. These are most numerous about the 

 middle and hinder parts of the nasal fossae, and are largest at the back of 

 the septum near the floor of the nasal cavity. They are much smaller and 



