THE SUPERIOR MAXILLARY BOXES. 



193 



middle turbinated bone of the ethmoid, bounded below by a smooth concavity 

 which forms part of the middle meatus ; below this again is the inferior turbinated 

 crest (already described), where the process joins the body of the bone. Its upper 

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

 is thin, directed obliquely downward and forward, and presents a serrated edge 

 for articulation with the nasal bone : its posterior border is thick, and hollowed 

 into a groove, the lachrymal groove, for the nasal duct : of the two margins of this 

 groove, the inner one articulates with the lachrymal bone, the outer one forms 

 part of the circumference of the orbit. Just where the latter joins the orbital 

 surface is a small tubercle, the lachrymal tubercle : this serves as a guide to the 

 position of the lachrymal sac in the operation for fistula lachrymalis. The 

 lachrymal groove in the articulated skull is converted into a canal by the lachrymal 

 bone and lachrymal process of the inferior turbinated ; it is directed downward, 

 and a little backward and outward, is about the diameter of a goose-quill, slightly 



Anterior palatine canal. 



Foramina of Stenson. 



Foramen of Sear pa. 



Posterior palatine canal. 



Accessory palatine foramina. 



FIG. 156. The palate and alveolar arch. 



narrower in the middle than at either extremity, and terminates below in the 

 inferior meatus. It lodges the nasal duct. 



The Alveolar Process is the thickest and most spongy part of the bone, broader 

 behind than in front, and excavated into deep cavities for the reception of the teeth. 

 These cavities are eight in number, and vary in size and depth according to the 

 teeth they contain. That for the canine tooth is the deepest ; those for the molars 

 are the widest, and subdivided into minor cavities ; those for the incisors are single, 

 but deep and narrow. The Buccinator muscle arises from the outer surface of this 

 process, as far forward as the first molar tooth. 



The Palate Process, thick and strong, projects horizontally inward from the 

 inner surface of the bone. It is much thicker in front than behind, and forms a 

 considerable part of the floor of the nostril and the roof of the mouth. 



Its inferior surface (Fig. 156) is concave, rough and uneven, and forms part of 

 the roof of the mouth. This surface is perforated by numerous foramina for the 

 passage of the nutrient vessels, channelled at the back part of its alveolar border 

 by a longitudinal groove, sometimes a canal, for the transmission of the posterior 

 palatine vessels, and the anterior and external palatine nerves from Meckel's gan- 



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