NASAL CAVITIES 



305 



separable into two districts, viz., a lower or respiratory 

 area, and a much smaller upper or olfactory area, comprising 

 not more than the upper third of the septum, in which 

 branches of the olfactory nerve spread out. The respiratory 

 mucous membrane is very thick and spongy. It is highly 

 vascular and contains numerous mucous glands. The minute 

 orifices of the gland ducts can be detected by the naked 

 eye. Over the olfactory district of the septum the mucous 



FrontrtTsibos 



Vestibule oi 

 nasal cavity 



Opening of 

 vomero-nasal organ 



Sublingual gland 

 Mandibl 



Septal^artilage 



rpendicular lamina of ethmoid 

 Vomer 



Sphenoidal air sinus 



Torus tubarius 



Opening of auditory 

 tube 



Pharyngeal recess 

 -Pharyngeal tonsil 



Anterior arch of atlas 



Soft palate 

 Transverse ligament 



Epistropheus 

 Epiglottis 



Hyoid bone 



FIG. 114. Antero-posterior section through the Nose, Mouth, and 

 Pharynx, a little to the left of the median plane. 



membrane is softer and more delicate, and not so thick. In 

 the fresh state it presents a yellowish colour, and the glands 

 are smaller. 



In favourable cases a minute orifice may be detected in the mucous 

 membrane on the lower and anterior part of the nasal septum, immediately 

 posterior to the vestibular area. It is placed above the anterior end of a 

 well-marked elongated projection which passes obliquely backwards and 

 upwards, and corresponds to the thickened lower margin of the septal 

 cartilage. The aperture varies in diameter from | mm. to i^ mm. 

 (Schwalbe). It leads into a narrow canal, which passes backwards for 

 a short distance, and then ends blindly. It is of interest because it 

 tepresents in the human subject the rudiment of the vomero-nasal organ 

 VOL. Ill 20 



