THE PALATE BONES. 91 



after birth, seen to be divided by a horizontal suture into an upper and larger 

 and a lower and smaller division. In some quadrumana the malar bone consists 

 of two parts, an orbital and a malar, which are ossified by separate centres. 



Articulations. With four bones : three of the cranium, frontal, sphenoid, and 

 temporal ; and one of the face, the superior maxillary. 



Attachment of Muscles. To four : The Levator labii superioris proprius, 

 Zygornaticus major and minor, and Masseter. 



The Palate Bones. 



The Palate Bones (palatum, the palate) are situated at the back part of the 

 nasal fossae : they are wedged in between the superior maxillary bones and the 

 pterygoid processes of the sphenoid (Fig. 57). Each bone assists in the for- 



Orbital process. v MHK~ Nasal process. 



i. fiirbiiiittril ci-t'xt. 



Sphe no -palatine /or. v 



Fphenoidal process. 



Sup. turbinated crest. ;j 



.,^^^^. -.__. 'Inf. turbinated crest. 



| m * a ':"-^^f. l^Vl 



f l/fljfaft^K Br*sv.,a 



Inf. turbinated crest.. 



\Fmfcrij>r iff IJv' v 



ST ,~, ~ /--.,-. wP r.. ,*A . 



Ant. nasal spine. 



FIG. 57. Palate bone in situ. 



mation 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 two fossae, the 

 spheno-maxillary and pterygoid; and one fissure, the spheno-maxillary. In 

 form the palate bone somewhat resembles the letter L, and may be divided into 

 an inferior or horizontal plate and a superior or vertical plate. 



The Horizontal Plate is 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 nose. 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 part of the aponeu- 

 rosis of the Tensor palati muscle. At the outer extremity 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 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 muscle. The external border is united with the lower part of the perpen- 



