ANATOMY IX A NUTSHELL. 537 



The internal surface is divided into two partsby the palate process. The 

 part above the palate process forms part of the outer wall of the nasal fossa 

 and has the large opening of the antrum of Highmore. The part below the 

 palate process forms part of the roof of the mouth and is concave. Above the 

 opening of the antrum of Highmore are half cells which are completed by artic- 

 ulation with the ethmoid and lachrymal hones, while below the opening of the 

 antrum of Highmore is a smooth surface which forms part of the inferior meatus. 

 Behind this opening is a rough surface which articulates with the perpendicular 

 plate of the ethmoid. This surface is crossed obliquely by a groove which is 

 converted into the posterior palatine canal by its articulations with the palate 

 bone. The lachrymal groove is in front of the antrum of Highmore and lodges 

 the lachrymal duct. It is converted into a canal by its articulation with the 

 lachrymal and inferior turbinated hones. The inferior turbinated crest, which 

 articulates with the inferior turbinated hone, is anterior to the lachrymal 

 groove. The middle meatus is the concavity above this crest, while the part 

 below it is the inferior meatus. 



The antrum of Highmore (maxillary sinus) (Plate CCLXIV) is a pyramidal 

 cavity in the body of the superior maxillary bone. The apex of this cavity is 

 formed by the malar process and its walls are the orbital, facial, and zygomatic 

 surfaces of the body of the sphenoid bone. The outer wall of the nose forms 

 its base in which there is the opening. This opening is partly closed by the 

 ethmoid bone above, by the inferior turbinated below, by the palate bone 

 behind. The posterior dental canals, which are for the posterior dental vessels 

 and nerve, are on the posterior wall of this antrum. Processeson the floor of 

 the antrum are produced by first and second molar teeth. 



The malar process, which is triangular and rough, is situated between the 

 facial surface and the zygomatic surface and articulates with the malar bone. 

 This process gives partial origin to the Masseter muscle. 



The nasal process, which passes upward, inward and backward by the side 

 of the nose is triangular and thick. The Levator labii superioris alaeque nasi. 

 Orbicularis palpebrarum, and Tendo oculiare attached to its external surface. 

 Its interna] surface makes part of the outer wall of the nose. The upper part 

 of this surface articulates with the ethmoid hone completing the anterior 

 ethmoidal cells, while below this is the superior turbinated cresl which artic- 

 ulates with the middle turbinated bone. The middle meatus is immediately 

 below, and below the middle meatus is the inferior turbinated crest. 



The upper border of the nasal process articulates with the frontal bone. 



The anterior border of this process articulates with the nasal bone. 



The posterior border of this process has the lachrymal groove for the nasal 



duct, and the inner margin of this groove articulates ith the lachrymal bone. 



while the outer margin of this groove forms pari of the circumference of the 



Orbit. Where it joins with the orbital surface is the lachrymal tubercle. 



The lachrymal groove is made into a canal by the lachrymal bone and the 

 lachrymal process of the inferior turbinated bone. This canal which opens 

 into the inferior meatus, runs downward, outward, and backward. (Plate 

 CCLII.) 



