THE MOUTH. 



311 



posterior border circumscribes the orifice which establishes a communica- 

 tion between these two cavities. 



This partition, which continues the palate posteriorly, represents in its 

 external form a membranous valve, oblique from above to below and before 

 to behind, much longer than it is wide, and exhibiting for study two faces 

 and four borders. 



The inferior or anterior face, turned towards the mouth, shows longi- 

 tudinal folds and transverse ridges, with multitudes of orifices belonging to 

 the submucous glandulae. On its sides it is united to the base of the tongue 

 by means of two thick mucous columns, designated the posterior pillars 

 of the tongue. The superior or posterior face constitutes the anterior wall 

 of the pharynx ; it only exhibits some very slight longitudinal ridges. 



Fig. 152. 



MEDIAN LONGITUDINAL SECTION OF THE HEAD AND UPPER PART OF NECK. 



1, Upper lip ; 2, Premaxilla; 3, Hard palate ; 4, Tongue ; 5, Septum nasi ; 6, Nasal 

 bone; 7, Palatine arch; 9, Pterygoid bone; 10, Epiglottis; 11, Entrance to the 

 Eustachian tube; 12, Aiytenoid cartilage, 13, Cricoid cartilage ; 14, (Esophagus; 

 15, Frontal bone and sinus ; 16, Cerebrum ; 17, Corpus callosum ; 18, Cerebellum ; 

 19, Sphenoid bone ; 20, Medulla oblongata ; 21, Cervical ligament ; 22, Spinal 

 cord ; 23, Occipital bone ; 24, 24, Atlas ; 25, 25, Dentata ; 26, Trachea. 



The two lateral "borders are inserted into the walls of the two cavities 

 which the soft palate separates. The anterior border, continuous with the 

 palate, is attached to the palatine arch, and follows the curve described by 

 it. The posterior border, the only free one, has a . concave form, and 

 closely embraces the base of the epiglottis, which is most usually found 

 reversed on the posterior surface of this curtain. This border is continued 

 at its extremites by two thin prolongations, which can be followed on the 

 lateral walls of the pharynx to the cesophageal infundibulum, above which 

 they unite in the form of an arch. These prolongments are named the 

 posterior pillars of the soft pa j ate, in contradistinction to the two mucous 

 folds at the base of the tongue, which constitute, by their relation to this 

 partition, veritable anterior pillars. This posterior border concurs to cir- 

 25 



