394 



HEAD AND NECK 



the septal cartilage. The posterior part of the roof is com- 

 posed of the anterior and under surfaces of the body of the 

 sphenoid, and also of the ala of the vomer, the sphenoidal 

 process of the palate bone, and the vaginal process of the 

 medial pterygoid lamina, all of which are applied to the under 

 surface of the sphenoidal body. 



Anterior 

 ethmoidal cell 



Infundibulu 



Posterior angle of 



septal cartilage 



between vomer "^ 



and perpendicular 



lamina of ethmoid 



Orbital cavity 



Middle meatu 

 Middle conch 



Inferior meatus 



Inferior conchz 



FIG. 154. Posterior aspect of Frontal section through the Nasal 

 Cavities opposite the Crista Galli of the Ethmoid Bone. 



The upper arrow shows the opening of an anterior ethmoidaj cell into the hiatus 

 semilunaris. The lower arrow passes from the maxillary sinus into the hiatus 

 semilunaris. 



The floor of the nasal cavity is of considerable width. It is 

 formed by the palatal processes of the maxilla and the palate 

 bones, and is concave from side to side. Further, it presents 

 a gentle antero-posterior slope, being slightly higher anteriorly 

 than posteriorly. On the anterior part of the floor, and close 

 to the septum nasi, the dissector may see a minute funnel- 

 shaped depression of the muco-periosteum into the incisive 

 foramen. This is of interest from a developmental point of 

 view ; for it is a vestige of the extensive communication which 



