894 



ORGAXS OF SPECIAL SEysE 



olfactory region is lined with a columnar unciliated epithelium. The mucous 

 membrane is here of a yello^vish colour, thicker than elsewhere, and contains the 

 olfactory cells of Max Schultze. 



The lower or resi)irat(»ry is a much wider portion, in wliicli the eiiithelium is 

 columnar and cihated, and includes the inferior turbinal l)()ne with the lower jjart 

 of the fossa. 



Immediately l)eliind the vestilnilc there are Iavo shallow depressions separated 

 by a ridge, the agger nasi, or naso-turl)inal; the area below the ridge is the atrium 

 of the middle meatus. It is bounded posteriorly by the anterior vertical border 

 of the middle turbinal, beneath which it is continued into the middle meatus. The 

 upper depression is the sulcus olfactorius; it leads upwards and backwards to the 

 olfactory region of the nasal fossa. 



The roof })resents Ijut one opening posteriorly, which leads into the sphenoidal 

 sinus. The orifices in the cribriform plate are entirely closed over. 



Fig. 517. — Oblique Section passing through the Nasal Foss.e, just in front of the 

 Posterior Xares. (Seea from behind.) 



Front wall of left 

 sphenoidal sinus 

 with orifice below 



Orifice of right sphe- . 



noidal sinus 



SUPERIOR TURBINAL _. 

 BONE ff, 



MIDDLE TURBINAL BONE 



ORIFICE OF EUSTACHIAN 

 TUBE 



UPPER SURFACE OF 

 SOFT PALATE 



CRISTA GALL! 



A closed anterior 

 ethmoidal cell 



""/^^/v POSTERIOR ETHMOIDAL 



CELLS 



RIGHT ANTRUM WITH 

 ORIFICE 



INFERIOR TURBINAL 

 BONE 



ORIFICE OF EUSTACHIAN 

 TUBE 



In the floor the openings leading into the anterior palatine canal are closed. 

 The small cul-de-snc already described indicates their position. 



The superior meatus is the shortest of the three; it lies in the posterior third 

 of the outer wall under cover of the sujserior turbinal bone, and it has but a single 

 opening, which leads into the posterior ethmoidal cells. The spheno-palatine 

 foramen is entirely covered by membrane. 



The middle meatus lies in the pcisterior two-thirds of the nasal chamber under 

 cover of the middle turbinal bone. On its outer Avail is a rounded eminence, the 

 bulla ethmoidalis, which is perforated by the aperture of the middle ethmoidal 

 cells; and in front and below this is a curved groove, the sulcus semilunaris, whicli 

 is continued above, by the infundil)ulum, into the frontal sinus; it receives the 

 openings of the anterior ethmoidal cells and the antrum. 



The inferior meatus is the longest of the three; it lies under cover of the 

 inferior turbinal bone, and it receives the nasal duct anteriorly. The mucous 

 membrane is arranged around the opening in a circular valve, the valve of Hasner, 

 which is sometimes double (page 8G8). 



