THE NASAL CAVITIES. 



523 



Fig. 309. 



11/ 



of the inferior or anterior compartment of these osteo-cartilaginous columns. It 

 also penetrates, by the semicircular opening of this meatus, into the sinus, to give 

 it its mucous lining, and is likewise prolonged into the canal of Jacobson. 

 Behind, it is continuous with the lining membrane of the pharyngeal cavity. 



Its deep face is separated by the periosteum or perichondrium, from the bony 

 or cartilaginous walls on which it is spread ; and it is united to the two precited 

 layers, this union being closest where it is thinnest, although it can always be 

 easily distinguished from them throughout the whole extent of the nasal fossa. 

 The free, or superficial face, presents numerous glandular orifices, and is constantly 

 covered by an abundance of mucus, that prevents the desiccation to which this 

 surface is exposed by the incessant movement of air over it. 



Steuctuee. — The organization of the pituitary membrane resembles that of 

 other mucous membranes, but it also presents some difi'erences according as 

 it is examined near the nostrils or deeper in the cavities. It is also usual 

 to divide it into two portions — the olfactory mucous 

 memhrane, which covers the upper part of the ethmoidal 

 turbinated bone and cells ; and the Schneiderian mem- 

 brane, fining the inferior two-thirds of the nasal cavities. 



The corium {tunica propria) of the Sclmeiderian mem- 

 hrane {regio respiratoria) is thick, soft, spongy, and rose- 

 coloured, and contains a large number of vessels and 

 glands. The latter are mucus or racemose glands, and 

 are extremely abundant in the layer covering the septum 

 of the nose, as well as at the inner face of the carti- 

 laginous appendages of the turbinated bones ; though 

 they are rare or altogether absent on the external face 

 of the latter. The epithelium is ciliated and stratified, 

 the deeper cells being spherical, those on the surface 

 cyhndrical. 



The olfactory mucous memhrane {regio olfactoria) 

 differs from the preceding by its greater thinness, its 

 delicateness, its slightly yellow tint, and the character 

 of its epithelium. The corium {tunica propria) contains 

 straight or slightly convoluted tubular glands — the glands 

 of Bowman. The epithelium is columnar and stratified, 

 and readily alters ; in animals it is destitute of cifia. 

 The deeper cells contain some yellowish pigment granules. 

 Schultze describes as olfactory cells, certain fusiform 

 elements which he considers are concerned in olfaction, 

 prolongations — a deep one, which is connected with the fibres of the olfactory 

 nerve ; and a superficial, that enters between the epithelial cells, and tends to 

 approach the free surface of the membrane. 



(The " olfactory cells " are thin, rod-like bodies (Fig. 309, b), presenting 

 varicose enlargements which are connected with processes of deeper-seated nerve- 

 cells. The epithelial cylinders proper {d, e) are related at their bases with the 

 septa of connective tissue belonging to the sub-epithelial glandular layer, and are 

 probably in communication with the olfactory cell. Schultze describes another 

 set of epithelial cells {a) as terminating externally by truncated flat surfaces, and 

 to all appearance not covered by any membrane, apart from the contents of the 

 cell, which are yellow, granular protoplasm, surrounding an oval nucleus lying 



CELLS OF THE OLFACTORT 



MUCOUS MEMBRANE. 



a, b, c, After Schultze; 

 d, e, f, after Lockhart 

 Clarke. 



These cells have two 



