THE MOUTH. 



399 



Vessels and nerves. — The external maxillary, coronary, and buccal arteries carry 

 blood to the cheeks. The veins empty them- 

 selves into the satellite branches of these Fig. 215 

 arteries. 



The lymphatics proceed to the submaxillary 

 glands. The nerves are of the same kind, and 

 proceed from the same source, as those sup- 

 plying the lips : being the seventh pair of 

 cranial nerves for the muscular layer, and the 

 fifth pair for the integuments (with lilaments 

 of the sympathetic for the blood-vessels and 

 labial glands.) 



Functions. — The cheeks are very active 

 agents in mastication, by constantly pushing 

 the aliment, through the action of the bucci- 

 nator, between the dental grinding surfaces. 



3. The Palate (Fig. 215). 



Preparation. — Separate the head from the trunk ; 

 saw tlirough the branches of the inferior maxilla above 

 tlie angle of the jaw, and from the crown of the last 

 molar tooth, so as to pas.s 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 bucci- 

 nator muscles, and so exposing the hard and soft 

 palates in such a manner as to render easy the special 

 dissections necessary for their study. For the palate, 

 these dissections are limited to the removal of the 

 mucous layer covering the deep venous network, and 

 to tlie partial excision of this, which allows the artery 

 and palatine nerves to be seen (see Fig. 215). 



The palate {hard palate), palatine arch, or 

 icp})er wall of the mouth, is circumscribed, in 

 front and on the sides, by the superior dental 

 arch, and limited, behind, by the anterior 

 border of the soft palate. It is a parabolic 

 surface, exactly representing, in its configura- 

 tion, the bony palate (Fig. 50). 



On its surface 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, 

 the concavities of which are turned backwards, 

 and which become narrower and less marked 

 as they are more posterior. (These arches and 

 furrows aid in retaining the aliment which the 

 tongue carries towards the palate during 

 deglutition.) 



THE HARD AND SOFT PALATE OF THE 

 HORSE. 



The mucous membrane has been removed 

 from the right side, and, with the 

 glandular layer, from the soft palate. 

 1, The ridges of the palatine mucou* 

 membrane ; 2, venous network of the 

 deep layer, which is incised at the 

 external side to show the palatine 

 artery, 3, accomjianied by the fila- 

 ments of the palatine nerve ; 4, car- 

 tilaginous digitation, over which passes 

 and is inflected the palatine artery ; 

 5, aponeurosis of the soft palate ; 5', 

 terminal e.xtremity of the tendon of 

 the tensor palati, forming by its ex- 

 pansion the sta|ihyline aponeurosis; 6, 

 the pharyngo-staphylmus ; 7, the pa- 

 lato-staphyiinus; 8, staphyline nerves. 



