THE PALATE BONE 55 



attachment of the aponeurosis of the tensor palati muscle. 

 At the outer extremity of this ridge is a deep groove con- 

 verted into a canal by its articulation with the tuberosity of 

 the superior maxillary bone, and forming the posterior palatine 

 canal. Near this groove the orifices of one or two small canals, 

 accessory posterior palatine, may frequently be seen. The 

 anterior border is serrated, bevelled at the expense of its inferior 

 surface, and articulates with the palate process of the superior 

 maxillary bone. The posterior border is concave, free, and 

 serves for the attachment of the soft palate. Its inner extremity 

 is sharp and pointed, and, when united with the opposite 

 bone, forms a projecting process, the posterior nasal spine, 

 for the attachment of the azygos uvulae. The external border 

 is united with the lower part of the perpendicular plate almost 

 at right angles. The internal border, the thickest, is serrated 

 for articulation with its fellow of the opposite side; its superior 

 edge is raised into a ridge which, united with the opposite 

 bone, forms a crest in which the vomer is received. 



The vertical plate is thin; its nasal surface is divided into 

 two parts by the inferior turbinate crest for the inferior turbi- 

 nate bone; the middle meatus is above it and the inferior 

 below. At the upper part is the superior turbinate crest for 

 the middle spongy bone, and above this a groove in the superior 

 meatus. The external surface presents above and behind a 

 smooth surface, forming the inner wall of the pterygomaxillary 

 fissure, and leads to the posterior palatine groove. In front 

 of the groove the surface is applied to the superior maxilla 

 and sends the maxillary process forward, closing in the lower 

 back part of the opening of the antrum. Behind the groove 

 the surface articulates below with the maxilla and above with 

 the pterygoid process. 



The pyramidal process or tuberosity juts out behind and 

 fits between the pterygoid plates; it presents posteriorly a 

 smooth middle district entering into the pterygoid fossa; 

 internal to it is a groove for the internal pterygoid plate, and 

 externally a rough area for the external plate. Part of the 

 tuberosity appears in the zygomatic fossa. Inferiorly, close 

 to the horizontal plate, are the posterior and external accessory 

 palatine canals. 



The orbital process rests on the anterior margin of the verti- 

 cal plate; it has five surfaces, three articular, and two, the 

 superior and external, are free. 



