THE BONES OF THE HEAD 145 



from the main canal. Anteriorly is the spheno-maxillary fissure. 

 Externally the fossa communicates with the zygomatic fossa through 

 the pterygo- maxillary fissure. 



5. The Inferior Region. 



The inferior region or external base (norma basilaris), from which 

 the inferior maxilla is excluded, is limited in front by the central 

 portions of the alveolar borders of the superior maxillae, and behind 

 by the superior curved hues of the occipital. At either side it is 

 limited by the lateral portion of the alveolar border of the superior 

 maxilla, and by a line connecting the tuberosity of that bone with 

 the lateral angle of the tabular part of the occipital. It is very 

 irregular, and presents three divisions — anterior, middle, and 

 posterior. 



The anterior division forms the hard palate, and resembles 

 a horseshoe. It is bounded in front and laterally by the alveolar 

 borders of the superior maxillae, and behind by the posterior 

 borders of the horizontal plates of the palate bones. The posterior 

 border presents in the middle line the posterior nasal spine in two 

 halves, from which the azygos uvTilae muscle arises. At either 

 side of this it is sharp and concave for the attachment of the soft 

 palate. The bones forming the hard palate are the palatal pro- 

 cesses of the superior maxillae over the anterior three- fourths, and 

 the horizontal plates of the palate bones over the posterior fourth. 

 The surface is vaulted, and is intersected by two sutmres, middle 

 palatal and transverse palatal. The middle palatal suture extends 

 from the alveolar point to the posterior nasal spine, and indicates 

 the meeting of the palatal plates of the superior maxillae and palate 

 bones of opposite sides. The transverse palatal suture crosses 

 the middle one at right angles about h inch in front of the posterior 

 border, and externedly it turns backwards to end at the posterior 

 palatine foramen. It indicates the meeting of the palatal process 

 of the superior maxilla and the horizontal plate of liie palate bone 

 of either side. 



In young skulls two additional sutures are present, called 

 maxiUo-premaxillary, each of which extends from the posterior 

 part of the anterior palatine fossa to the inter^^al between the 

 lateral incisor and canine teeth. Each of these sutures corre- 

 sponds with the place of junction of the maxilla proper and the 

 premaxilla. 



The hard psdate presents several openings. At the anterior 

 extremity of the middle palatal suture is the diamond-shaped 

 anterior palatine fossa. Within this are four openings, two being 

 placed laterally, one at either side, called the foramina of Stensen 

 (incisor foramina), and two in the median line in the intermaxillary 

 suture, called the foramina of Scarpa, anterior and posterior respec- 

 tively. Each of the former transmits a branch of the descending 



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