THE INTERIOR OF THE SKULL 



195 



and nerves and by the grooves for the nasopalatine nerve, and is traversed by 

 sutures connecting the bones of which it is formed. 



The lateral wall (Fig. 196) is formed, in front, by the frontal process of the 

 maxilla and by the lacrimal bone; in the middle, by the ethmoid, maxilla, and 

 inferior nasal concha; behind, by the vertical plate of the palatine bone, and the 

 medial pterygoid plate of the sphenoid. On this wall are three irregular antero- 

 posterior passages, termed the superior, middle, and inferior meatuses of the nose. 

 The superior meatus, the smallest of the three, occupies the middle third of the 

 lateral wall. It lies between the superior and middle nasal conchse; the spheno- 

 palatine foramen opens into it behind, and the posterior ethmoidal cells in front. 

 The sphenoidal sinus opens into a recess, the sphenoethmoidal recess, which is placed 

 above and behind the superior concha. The middle meatus is situated between the 

 middle and inferior conchse, and extends from the anterior to the posterior end of 



Nasal bone 

 Frontal spine 



Cribriform plate of ethmoid^ 

 Sphenoid 



Probe passed through 



nasolacrimal canal 

 Bristle pa-ssed through 

 infundibulum 



Anterior nasal spine 

 Palatine proc. of maxilla 

 E yrizontal part of palatm 

 Posterior nasal spine 



i Incisive canal- 



I 





- Frontal prpc. of maxilla 



- Laerimal 

 Ethmoid 



Uncinate proc. of ethmoid 

 Inferior nasal concha 

 Palatine 



Superior meatus 

 Middle meatus 

 Inferior meatus 



FIG. 196. Roof, floor, and lateral wall of left nasal cavity. 





the latter. The lateral wall of this meatus can be satisfactorily studied only after 

 the removal of the middle concha. On it is a curved fissure, the hiatus semilunaris, 

 limited below by the edge of the uncinate process of the ethmoid and above by 

 an elevation named the bulla ethmoidalis; the middle ethmoidal cells are contained 

 within this bulla and open on or near to it. Through the hiatus semilunaris 

 i;he meatus communicates with a curved passage termed the infundibulum, which 

 communicates in front with the anterior ethmoidal cells and in rather more than 

 fifty per cent, of skulls is continued upward as the frontonasal duct into the frontal 

 air-sinus; when this continuity fails, the frontonasal duct opens directly into the 

 anterior part of the meatus. Below the bulla ethmoidalis and hidden by the unci- 

 nate process of the ethmoid is the opening of the maxillary sinus (ostium maxillare) ; 

 an accessory opening is frequently present above the posterior part of the inferior 

 nasal concha. The inferior meatus, the largest of the three, is the space between 

 the inferior concha and the floor of the nasal cavitv. It extends almost the entire 



