NASAL CAVITIES. 165 



ment of the squamous suture is well seen in this fossa, also the 

 junction of the pterygoid bone with the parietal and frontal, by 

 the overlapping of the great wing of the former. At the inferior 

 part of the latter, is the pointed process, from which one head 

 of the external pterygoid muscle arises. 



At the bottom of the temporal fossa there is a narrow slit 

 partitioned from the nose by the nasal plate of the palate bone. 

 This slit, from its position, is called the Pterygo-maxillary fossa. 

 It is triangular, the base being upwards and the point down- 

 wards. The base reaches to the bottom of the orbit. From 

 the base there leads into the nose the spheno-palatine foramen 

 for transmitting the lateral nasal nerve and blood vessels. Ex- 

 ternally to this foramen, and somewhat above it, is the foramen 

 rotundum for the upper maxillary nerve. On a level with the 

 spheno-palatine foramen, and running horizontally through the 

 base of the pterygoid process, is the pterygoid foramen for the 

 nerve of the same name. Running vertically downwards from 

 the point of the pterygo-maxillary fossa, is the posterior pala- 

 tine canal for transmitting the nerve and artery of the same 

 name. The upper part or base of the pterygo-maxillary fossa, 

 is continuous with a large fissure in the bottom of the orbit 

 called the spheno-maxillary. 



SECT. V. OF THE NASAL CAVITIES. 



The nose consists of two large cavities or fossae, in the mid- 

 dle of the bones of the upper jaw, and has a very irregular sur- 

 face. Its cavities are separated from one another by a vertical 

 septum, consisting in the vomer and in the nasal lamella of the 

 ethmoid bone. This septum presents a surface which is per- 

 fectly prlane, with the exception, that in some subjects it is 

 slightly convex on one side, and concave on the other. It is 

 deficient in front. 



The upper part of either nostril is formed by the cribriform 

 plate of the ethmoid bone ; in front of this the surface is very 

 oblique, being made by the os nasi; posteriorly there is a ver- 

 tical gutter on the body of the sphenoid bone, in the middle of 

 which is the orifice of the sphenoidal cell. The distance be- 

 tween the cellular part of the ethmoid and the septum nasi is 



