166 



THE SKELETON. 



THE PALATE BONES. 



The Palate Bones are situated at the back part of the nasal fossae ; they are 

 wedged in between the superior maxillary and the pterygoid process of the 

 sphenoid. Each bone assists in the formation of three cavities; "the floor and 

 outer wall of the nose, the roof of the mouth, and the floor of the orbit ; and 

 enters into the formation of three fossae: the zygomatic, spheno-maxillary, 

 and pterygoid. In form the palate bone somewhat resembles the letter L, 

 and may be divided into an inferior or horizontal plate, and a superior or ver- 

 tical plate 



The Inferior or Horizontal Plate is thick, of a quadrilateral form, and presents 

 two surfaces and four borders. The superior surface, concave from side to 

 side, forms the back part of the floor of the nostril. The inferior surface, 

 slightly concave and rough, forms the back part of the hard palate. At its 

 posterior part may be seen a transverse ridge, more or less marked, for the 

 attachment of the aponeurosis of the Tensor Palati muscle. At the outer ex- 

 tremity of this ridge is a deep groove, converted 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 ex- 

 tremity 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 

 Uvulas. The external border is united with the lower part of the perpendicu- 

 lar plate almost at right 



Fig. 118. Left Palate Bone. Internal Yiew (enlarged). angles. The internal bor- 

 der, the thickest, is ser- 

 rated 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 re- 

 ceived. 



The Superior or Vertical 

 Plate (Fig. 118) is thin, of 

 an oblong form, and di- 

 rected upwards and a lit- 

 tle inwards. It presents 

 two surfaces, an external 

 and an internal, and four 

 borders. 



The internal surface 

 presents, at it lower part, 

 a broad shallow depres- 

 sion, which forms part of 

 the inferior meatus of the nose. Immediately above this is a well-marked 

 horizontal ridge, the inferior turbinated crest, for articulation with the inferior 

 turbinated 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 



fifht 



McuriTZttry 



HORIZONTAL F LATE. 



