PALATE BOXE. 



89 



Sup* T 

 fjilitna. f, dating F 



MaxiHary 

 Process 



HORIZONTAL FLATC 



The Vertical Plate (fig. 51) is thin, of an oblong form, and directed upwards 

 and a little inwards. It 



presents tWO surfaces, an Fi S- 51. Left Palate Bone. Internal View (enlarged), 



external and an internal, 

 and four borders. 



The internal surf ace pre- 

 sents at its lower part a 

 broad shallow depression, 

 which forms part of the 

 inferior meatus of the nose. 

 Immediately above this is 

 a well-marked horizontal 

 ridge, the inferior turbi- 

 nated crest, for articula- 

 tion with the inferior tur- 

 binated bone ; above this, 

 a second broad shallow 

 depression, which forms 

 part of the middle meatus, 

 surmounted above by a 

 horizontal ridge, less pro- 

 minent than the inferior, 

 the superior turbinated 

 crest, for articulation with 

 the middle turbinated bone. Above the superior turbinated crest is a narrow 

 horizontal groove, which forms part of the superior meatus. 



The external surface is rough and irregular throughout the greater part of its 

 extent, for articulation with the inner surface of the superior maxillary bone, its 

 upper and back part being smooth where it enters into the formation of the 

 zygomatic fossa ; it is also smooth in front, where it covers the orifice of the 

 antrum. Towards the back part of this surface is a deep groove, converted into a 

 canal, the posterior palatine, by its articulation with the superior maxillary bone. 

 It transmits the posterior palatine vessels and a large nerve. The anterior border 

 is thin, irregular, and presents opposite the inferior turbinated crest a pointed 

 projecting lamina, the maxillary process, which is directed forwards, and closes 

 in the lower and back part of the opening of the antrum, being received into a 

 fissure that exists at the inferior part of this aperture. The posterior border 

 (fig. 52) presents a deep groove, the edges of which are serrated for articulation 

 with the pterygoid process of the sphenoid. At the lower part of this border is 

 seen a pyramidal process of bone, the pterygoid process or tuberosity of the palate, 

 which is received into the angular interval between the two pterygoid plates of 

 the sphenoid at their inferior extremity. This process presents at its back part 

 three grooves, a median and two lateral ones. The former is smooth, and forms 

 part of the pterygoid fossa, affording attachment to the Internal pterygoid muscle ; 

 whilst the lateral grooves are rough and uneven, for articulation with the anterior 

 border of each pterygoid plate. The base of this process, continuous with the 

 horizontal portion of the bone, presents the apertures of the accessory descending 

 palatine canals ; whilst its outer surface is rough, for articulation with the inner 

 surface of the body of the superior maxillary bone. The superior border of the 

 vertical plate presents two well-marked processes, separated by an intervening 

 notch or foramen. The anterior, or larger, is called the orbital process; the 

 posterior, the sphenoidal. 



The Orbital Process, directed upwards and outwards, is placed on a higher 

 level than the sphenoidal. It presents five surfaces, which inclose a hollow cellu- 

 lar cavity, and is connected to the perpendicular plate by a narrow constricted 

 neck. Of these five surfaces, three are articular, two non-articular or free sur- 

 faces. The three articular are the anterior or maxillary surface, which is directed 



