THE FOSSAE. 



31 



THE FOSSAE. 



Describe the Nasal Fossae. Together they form the cavity of the nose, 

 oeing separated from each other by the Septum Nasi. 11 They open in front 

 by the anterior nares, behind by the posterior nares ; and extend from the 

 palate processes of the superior maxillary and palate bones, 17 upwards to the 

 base of the cranium. They are formed by 14 bones, the ethmoid, sphenoid s 

 frontal, vomer, 2 nasal, 2 superior maxillary, 2 lachrymal, 2 palate, and 2 

 inferior turbinated. 



Describe the Septum Nasi. 11 It forms the inner wall of each nasal 

 fossa, and is formed chiefly by the perpendicular plate of the ethmoid bone, 

 the vomer, and the triangular cartilage of the septum ; to a less extent by 5 

 other bones, the rostrum of the sphenoid, the nasal spine of the frontal, and 

 the crests of the nasal, palate, and superior maxillary bones. 



Describe the points presented by each Nasal Fossa. They are 

 ON THE ROOF. 



Openings, posteriorly, into the sphenoidal sinuses. 



Olfactory Foramina, and the Nasal Slit, in the cribriform plate of the eth- 

 moid bone. 



ON THE FLOOR. 



Orifice, of the anterior palatine canal. 

 Suture, between the bones forming the hard palate. 

 Nasal Spines, anterior and posterior, and the Ridge connecting them. 

 ON THE OUTER WALL, from above downwards. 



Superior Turbinated process of FIG. 13. 



the ethmoid. 

 Stiperior Meatus of the nose, into 



which open 3 orifices, those 



of the posterior ethmoidal and 



the sphenoidal sinuses, and the 



spheno-palatine foramen. 



Middle Turbinated ' 7 process of 

 the ethmoid. 



Middle Meatus of the nose, into 



which open 2 orifices, those 



of the antrum 14 and infundib- 



ulum, the latter draining the 



anterior ethmoidal cells, 8 and the frontal sinus. 

 Inferior Turbinated Bone^ below which is the 



