THE MAXILLAEY BONES. 



147 



Ridge for middle 

 concha 



Middle meat 



Anterior nasal 

 spine 



Alveolar 

 process 



Nasal crest 

 FIG. 158. THE RIGHT MAXILLA (Medial Aspect). 



The infra - temporal or postero - lateral surface is separated above from 

 'the orbital aspect by a rounded free edge, which forms the anterior margin 

 of the inferior orbital 



fissure in the articulated Frontal P rocess 



; skull. Inferiorlyand an- 

 | teriorly it is separated 

 i from the anterior surface 

 by the zygomatic process 

 and its free lower border. 

 Medially it is limited by 

 a sharp, irregular margin 

 with which the palate 

 bone articulates. This 

 surface is more or less 

 convex, and is directed 

 towards the infra-tem- 

 poral and pterygo-pala- 

 tine fossae. It is pierced 

 in a downward direction 

 by the apertures of the 

 alveolar canals (foramina 

 alveolaria), two or more 

 in number, which trans- 

 mit the corresponding 

 nerves and vessels to the 

 molar teeth. Its lower 

 part, slightly more pro- 

 minent where it over- 

 hangs the root of the third molar, is often called the tuber maxillare (maxillary 

 tuberosity). 



The planum orbitale (orbital surface), smooth and plane, is triangular in shape 

 and forms part of the floor of the orbit. Its anterior edge corresponds to the 

 infra-orbital margin; its posterior border coincides with the anterior boundary 

 of the inferior orbital fissure. Its thin medial edge, which may be regarded 

 as the base of the triangle, is notched in front to form the sulcus lacrimalis 

 (lacrimal groove), behind which it articulates with the lacrimal bone for a short 

 distance, then for a greater length with the lamina papyracea of the ethmoid, 

 and terminates posteriorly in a surface for articulation with the orbital process 

 of the palate bone. Its lateral angle corresponds to the base of the zygomatic 

 process. Traversing its substance is the infra-orbital canal, the anterior opening of 

 which has been already noticed on the anterior aspect of the body. Behind, however, 

 owing to deficiency of its roof, the canal forms a groove which lips the edge of the 

 bone which constitutes the anterior boundary of the inferior orbital fissure. If this 

 canal be laid open, the orifices of the middle and anterior alveolar canals will be 

 seen, which transmit the corresponding vessels and nerves to the premolar, canine 

 and incisor teeth. 



The facies nasalis (nasal surface) of the body is directed medially towards the 

 nasal cavity. Below, it is confluent with the superior surface of the palatine process ; 

 anteriorly it is limited by the sharp edge of the nasal notch ; above and anteriorly it 

 is continuous with the medial surface of the frontal process ; behind this it is deeply 

 channelled by the lacrimal groove, which is converted into a canal by articulation 

 with the lacrimal and inferior conchal bones. The channel so formed conveys the 

 naso-lacrimal duct from the orbital cavity above to the inferior nasal meatus below. 

 Behind this groove the upper edge of this area corresponds to the medial margin 

 of the orbital surface, and articulates from before backwards with the lacrimal, 

 lamina papyracea of the ethmoid, and the orbital process of the palate bone. The 

 posterior border, rough for articulation with the palate bone, is traversed obliquely 

 from above downwards and slightly medially by a groove, which, by articulation 

 with the palate bone, is converted into the pterygo-palatine canal, which transmits 



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