THE SUPERIOR MAXILLARY BONES 53 



the inferior meatus; above it a small surface forming the atrium 

 (entry) of the middle meatus. Behind the nasal process is 

 the lacrymal groove, J inch long, inclined down and out, open- 

 ing into the inferior meatus; the groove is converted into the 

 canal of the nasal duct by the lacrymal and inferior turbinate. 

 Behind it is the opening of the antrum; above this are small 

 half-cells belonging to the middle ethmoidal set. Behind the 

 opening of the antrum the surface is rough for articulation 

 with the palate bone, and traversed by a groove running down 

 and forward, forming with the palate the posterior palatine 

 canal, for the posterior palatine vessels, anterior and external 

 palatine nerves. 



The orbital surface is triangular and flat; externally is a 

 rough surface for the malar; internally is first the lacrymal 

 notch, and behind it a pretty straight margin for the ethmoid 

 and orbital process of the palate. The posteroexternal border 

 is free and bounds the sphenomaxillary fissure. The infra- 

 orbital groove commences well back on this surface, leading 

 to a canal of the same name, which opens anteriorly at the 

 infraorbital foramen; from the canal are given off the anterior 

 and middle dental canals in the substance of the bone. 



The nasal process projects up, in, and back; its external 

 surface is smooth; the higher part of the inner surface com- 

 pletes the anterior ethmoidal cells; below this the surface is 

 crossed by the superior turbinate crest (agger nasi) for the 

 inferior turbinate process of the ethmoid (middle, spongy bone). 

 The anterior border articulates with the nasal bones and above 

 with the frontal; posteriorly is a continuation of the lacrymal 

 groove, bounded internally by a sharp edge articulating with 

 the lacrymal, and externally by a smooth border; where this 

 border joins the orbital surface is the lacrymal tubercle. 



The alveolar process is thick and hollowed into eight alveoli. 

 The malar process is triangular, continuous in front and behind 

 with the facial and zygomatic surfaces of the body. Superiorly 

 it is rough for the malar; the inferior border forms a thick 

 buttress opposite the first molar. 



The palate process with its opposite forms three-fourths 

 of the hard palate. Above, it is concave transversely, and 

 forms part of the floor of the inferior meatus. Below, it is 

 arched, and shows lateral grooves for nerves and vessels; its 

 posterior extremity falls short of that of the alveolar arch, 



