THE NASAL CAVITY. 49 



ethmoid and dislocate the septum toward the healthy side. The osseous septum is composed 

 of the perpendicular plate of the ethmoid bone and of the vomer. The alae of the vomer articu- 

 late with the lower surface of the body of the sphenoid; its lower border rests upon the nasal 

 crest of the hard palate, the posterior free border divides the two choanae, and the superior portion 

 of the anterior border of the bone is united with the perpendicular plate of the ethmoid. An- 

 teriorly the septum is completed by the triangular cartilage. 



The structure of the outer wall of the nasal fossa is complicated by the presence of the tur- 

 binated bones and of the orifices of the numerous accessory cavities (see Fig. 19). Above and in 

 front are the nasal bone, the nasal process of the superior maxilla, and the lachrymal bone; 

 behind these are the nasal surface of the superior maxilla with the large orifice of the antrum of 

 Highmore, the lateral masses of the ethmoid with the superior and middle turbinated bones, and, 

 still further posterior, the vertical plate of the palate bone and the pterygoid process of the sphe- 

 noid. The inferior turbinated bone, articulating with the inferior turbinated crests of the superior 

 maxillary and palate bones, is an independent bone (one of the six paired bones of the face). 



The inferior meatus is situated between the floor of the nasal cavity and the inferior turbi- 

 nated bone; the middle meatus is between the inferior and middle, and the superior meatus is 

 between the middle and superior turbinated bones. The meatuses communicate with the main 

 portion of the nasal cavity beneath the overhanging turbinated bones ; they run from before back- 

 ward, and are shorter and narrower as we pass from below upward. 



The nasal cavity communicates with the mouth through the bony anterior palatine canal, 

 which commences as a double foramen on the nasal floor, one foramen being situated to either 

 side of the nasal septum, and ends as a single foramen in the anterior portion of the oral surface 

 of the hard palate. The canal for the nasal duct passes down from the orbit to open into the 

 inferior meaius. The nasal fossa communicates with the cranial cavity through the numerous 

 foramina in the cribriform plate of the ethmoid (for the olfactory filaments) and with the spheno- 

 maxillary fossa through the spheno-palatine foramen (for the spheno-palatine artery and the 

 superior nasal and naso-palatine nerves). 



The wide orifice of the antrum of Highmore in the isolated superior maxillary bone is con- 

 siderably encroached upon during life by the articulation and imposition of neighboring bones. 

 These bones are the perpendicular plate of the palate bone, the inferior turbinated bone with its 

 maxillary process, and the uncinate process of the ethmoid. 



[Above and from before backward the outer osseous wall is made up by the nasal bone, 

 nasal process of the superior maxilla, lachrymal bone, lateral mass of ethmoid, and the orbital 

 process of the vertical plate of the palate bone. Below and from before backward the outer wall 

 is made up of the nasal aspect of the body of the sphenoid, the vertical plate of the palate, and 

 the inner plate of the pterygoid process of the sphenoid bone. 



The nasal aspect of the body of the superior maxilla presents the opening leading into the 

 antrum of Highmore (superior maxillary sinus). This opening is partially closed in by bone 

 and mucous membrane. The lower half is completely closed by the maxillary process of the in- 

 ferior turbinated and the maxillary process of the vertical plate of the palate bone. Above, the 

 antral opening is partially closed by the uncinate process of the ethmoid bone passing down 

 from before backward in a curved direction to articulate with the ethmoid process of the inferior 



