326 



THE RESPIRATORY SYSTEM 



posterior extremity of the inferior concha extends almost to 

 the choanae (posterior nares) and can therefore be inspected 

 on posterior rhinoscopy. The mucous membrane, which covers 

 it, is very loosely attached to the subjacent bone, and serous 

 effusions into the lax submucous tissue may cause complete 



FIG. 114. The Nasal Septum. 



a. Vomer. 



b. Perpendicular lamina of 



ethmoid. 



c. Septal cartilage. 



d. Naso-pharynx. 



e. Sphenoidal air-sinus. 



occlusion of the inferior meatus. This condition is found in 

 coryza, chronic posterior hypertrophic rhinitis, etc. 



The floor of the inferior meatus, which also constitutes 

 the floor of the nose, is formed by the hard palate and is 

 practically horizontal. 



The middle concha forms the roof of the middle meatus and 

 projects downwards and medially so as to obscure the orifices 



