TEE MOUTH. 



333 



maxilla above the angle of the jaw, and from the crown of the last molar tooth, so as to 



pass between the curtain of the soft palate on the one part, and the base of the tongue on 



the other, leaving the latter organ adherent to the lower jaw. This last should be 



removed from the upper jaw by cutting through the masseter'and alveolo-labial muscles, 



and so exposing the hard and soft palates in such 



a manner as to render easy the special dissections Fig. 148. 



necessary for their study. These dissections are 



limited to the removal of the mucous layer 



covering the deep venous network, and to 



the partial excision of this, which allows the 



artery an; I palatine nerves to be seen. (See 



figure 148.) 



The palate (hard palate), palatine arch, 

 or upper wall of the mouth, is circum- 

 scribed, in front and on the sides, by the 

 superior dental arcade, and limited, behind, 

 by the anterior border of the soft palate. 

 It is a parabolic surface, exactly repre- 

 senting, in its configuration, the bony 

 palate (Fig. 21). 



On its face is remarked a median 

 groove, which partitions it into two equal 

 divisions, and which commences quite in 

 front, at the base of a small tubercle. 

 Curved transverse furrows, twenty in 

 number (Leyh gives from sixteen to 

 eighteen), divide each of these halves 

 into an equal number of salient arches, 

 whose concavities are turned backwards, 

 and which become narrower and less 

 marked as they are more posterior. 

 (These arches and furrows aid in retain- 

 ing the aliment which the tongue carries 

 towards the palate during deglutition). 



STRUCTURE. The palatine lies on the 

 bony vault formed by the palatine and 

 supermaxillary bones. It includes in its 

 structure : 



1. A fibrous membrane, applied to the 

 bone just mentioned, which sustains a re- 

 markably-developed venous network con- 

 stituting a veritable erectile tissue, and 

 gives to the palate a greater or less 

 degree of thickness, according to its state 

 of turgescence (Fig. 148, 1). 



2. A mucous layer, extremely adherent, 



V *j 1 f* ,1 -.* A ij.j^j m\L\LJ AJXU B\JX A .f AJj 



by its deep face, to the preceding tissue, The mucous membrane has been 

 and of a whitish aspect in the horse. The from the right side, and, with the 

 COrium, formed entirely of connective glandular layer, from the soft palate. 



1, The ridges of the palatine mucous 



membrane; 2, Venous network of the deep layer, which is cut through at the 

 external side to show the palatine artery, 3, accompanied by the filaments of the 

 palatine nerve ; 4, Cartilaginous digitation, over which passes and is inflected the palatine 

 artery ; 5, Aponeurosis of the soft palate ; 5', Terminal extremity of the tendon of the 

 external tensor palati, forming by its expansion the staphylin aponeurosis; 6, The 

 palato-pharyngeus ; 7, Circumflexus palati ; 8, Staphylin nerves. 



THE HARD AND SOFT PALATE. 



