PREM AXILLA. 57 



very thick, and contains six quadrilateral cavities, termed alveoli, 

 in which the upper molar teeth are lodged. At the back of the 

 last alveolus is a large rounded eminence, the alveolar tuberosity, 

 and in front of the first the border becomes thin and sharjD, and 

 forms a portion of the diastema or interdental space, which 

 separates the molar from the incisor and canine teeth. The 

 internal border is serrated to articulate with its fellow of the 

 ojDposite side, notched anteriorly to form the incisive opening, 

 and it articulates posteriorly with the palatine bone. 



The posterior extremity is rounded and prominent, forming 

 the alveolar tid)erosity, in the interior of which the maxillary 

 sinus is prolonged. At the inner side of this eminence is a large, 

 deep excavation, which the palatine bone assists to form into the 

 maxillary hiatus. This hiatus is situated directly opposite to 

 the orbital hiatus, the spheno-maxillary fissure being the space 

 between them; the hiatus contains three foramina — 1st, the 

 ■palatine or palato-maxillary, which leads to the palatine groove, 

 for the i^assage of the jDalatine artery ; 2nd, the dental, which 

 enters the maxillary sinus, is continued along the roots of the 

 molar teeth, and divides into two branches— a large short one, 

 which opens at the infra-orbital foramen, and another continued 

 to the roots of the incisor teeth ; the 3rd is the splieno-palatine, 

 which enters the nasal chamber, and gives passage to the spheno- 

 palatine artery, vein, and nerve. The anterior extremity pre- 

 sents in the male a cavity which, with a similar cavity in the 

 premaxilla with which it articulates, forms the alveolus of the 

 canine tooth. 



The superior maxilla articulates with its fellow, and with the 

 premaxilla, ethmoid, squamosal, nasal, palatine, malar, lachrymal, 

 and inferior turbinal bones. 



PREMAXILLA. 



(Fig. 12. 10.) 



This bone, called also the Inter or Anterior maxillary bone, 

 is situated at the anterior extremity of the face, and consists of 

 a broad thick part and two processes which spring from it. 

 The thick part or base presents three surfaces — an external 

 or labial, which is smooth and convex ; an internal, which is 

 roughened to articulate with its fellow, and has a groove running 

 down it, which, with that of the opposing bone, forms the 



