THE SKULL. 



39 



which is for articulation with the cribriform plate of the ethmoid. 

 Craniad of this the surface is inarked by ridges and looks into 

 the nasal cavity. 



The cranial margin is produced dorsally in the form of a 

 blunt triangular spine. Mediad of this spine the bone articu- 

 lates with the lachrymal bone. 



The ventral border articulates by its cranial one-third with 

 the orbital plate of the palatine, and by its caudal two-thirds 

 with the body and w^ing of the presphenoid. 



Maxillary Bone. Maxilla (Figs. 27 and 28). — The 

 maxillary bone forms the cranial and lateral portions of the 

 roof of the mouth. The bones of opposite sides meet craniad, 

 but diverge caudad to enclose the palatal plates of the palatine 

 bones. Each consists of a thick prismatic ventral portion or 



Fig. 27. — Maxillary Bone, 

 Lateral Surface. 



Fig. 28. —Maxillary Bone, 

 Medial Surface. 



a, body; b. frontal process; f, infraorbital foramen; d, elevation for root of 

 canine tootli; e, canine ((joth;/", first premolar; g, second premolar; //, third pre- 

 molar; /, molar tooth; 7', zygomatic process; k, beginning of lachrymal canal; /, 

 ridge to which the ventral nasal concha is attached; w, nasal crest of palatine 

 process. 



body {a) and a thin flat plate, the frontal process {b), extending 

 dorsad from the cranial part of the bone. 



The body {a) has the form of a triangular prism whose 

 broader dorsal face looks into the nasal cavity and orbit, while 

 the ventral face looks into the mouth, and the lateral face 

 toward the cheek. From the junction of the dorsal and lateral 

 surfaces at the cranial end the large flat curved frontal process 

 {b) passes dorsad, while the teeth are implanted along the 

 border, alveolar border or process, formed by the junction of 

 the ventral and lateral surfaces. 



