THE NASAL CAVITY 



the lateral wall of this meatus is fully displayed. On it is a rounded elevation, 

 the bulla ethmoidalis, and below and in front of this is a curved cleft, the hiatus 

 semilunaris. 



The bulla ethmoidalis is caused by the bulging of the middle ethmoidal cells 

 which open on or immediately above it, and the size of the bulla varies with that 

 of its contained cells. 



Bristle in infundibulum 

 Cut edge of middle conclia 

 Hiatus semilunaris 

 Bulla ethmoidalis 



Opening of middle ethmoidal cells 

 Cut edge of superior concha 

 Openings of posterior ethmoidal cells 

 Bristle in opening ofsphenoidal sinus 



Orifice of ' Ph geal recess 



Bnstle in nasolacrimal canal 



Bristle in opening of 

 maxillary sinus 



FIG. 856. Lateral wall of nasal cavity; the three nasal conchse have been removed. 



The hiatus semilunaris is bounded inferiorly by the sharp concave margin of the 

 uncinate process of the ethmoid bone, and leads into a curved channel, the infundib- 

 ulum, bounded above by the bulla ethmoidalis and below by the lateral surface 

 of the uncinate process of the ethmoid. The anterior ethmoidal cells open into the 

 front part of the infundibulum, and this in slightly over 50 per cent, of subjects 

 is directly continuous with the f rontonasal duct or passage leading from the frontal 

 air sinus; but when the anterior end of the uncinate process fuses with the front 

 part of the bulla, this continuity is interrupted and the frontonasal duct then opens 

 directly into the anterior end of the middle meatus. 



Below the bulla ethmoidalis, and partly hidden by the inferior end of the uncinate 

 process, is the ostium maxillare, or opening from the maxillary sinus; in a frontal 

 section this opening is seen to be placed near the roof of the sinus. An accessory 

 opening from the sinus is frequently present below the posterior end of the middle 

 nasal concha. The inferior meatus is below and lateral to the inferior nasal concha; 

 the nasolacrimal duct opens into this meatus under cover of the anterior part of 

 the inferior concha. 



Medial Wall (Fig. 854). The medial wall or septum is frequently more or 

 less deflected from the median plane, thus lessening the size of one nasal cavity 



