THE PALATE. 



^569 



This is concave on each side, and presents a median elongation, the uvtda, which 

 varies from a short prominence to a cord 2 cm. in length. Thus the palate has 

 a lower surface looking downward and forward and an upper one looking upward 

 and backward. When the mouth is closed the palate and uvula rest against the 

 tongue ; when open they hang free, but the muscles inside can modify their shape 

 and position. Median sections show the tip of the uvula often reaching within half 



Fig. 1327. 



T,i,„„ I „ . Azygos uvulae Tendon of tensor palati 



Pharyngeal mucous membrane ^"^ Artery/ Levator palati Palato-pharyngeus 





Masses ot glatulb i.)iai ihulous nieuibrane 



Transverse section of soft palate near its anterior attachment. X 4. 



an inch of the tip of the epiglottis. Possibly muscular relaxation allows it to descend 

 somewhat farther than in life, but it is certain that no very great elongation is neces- 

 sary for it to touch that organ and give rise to great discomfort. The soft palate can 

 be raised so as to touch the back of the pharynx and close all communication between 

 the nose and the mouth. Two folds, the pillars of the fauces, each the reflection of 

 the mucous membrane over a muscular bundle, start from the palate on either side. 

 The anterior pillar, enclosing the palato-glossus muscle, arises from the front of the 

 palate near the uvula, some distance anterior to the edge, and, curving downward, 

 runs to the tongue at the junction of the middle and posterior thirds, separating the 

 mouth from the pharynx and forming the posterior border of the sublingiial space. 

 The posterior pillar starts from the lower border of the palate on either side of the 

 uvula, covering the palato-pharjmgeus, and runs down the throat to the superior cornu 

 of the thyroid cartilage, the lower part being indistinct. Some of the muscular fibres 

 within it go to the upper border of the thyroid cartilage in front of the horn, but the 

 fold is not often found so low, except in frozen sections, in which it appears at the 

 sides of the. back of the pharynx. 



A deep triangular recess on either side, between the anterior and posterior 

 pillars, contains the tonsil. This region is often vaguely described as the isthmus of 

 the fauces, one being left in doubt whether it belongs to the pharynx or to the mouth. 

 In the preceding pages the pharynx is described as beginning at the anterior pillar. 



The reasons for this divi- 

 sion are developmental, 

 morphological, and phys- 

 iological. The part of 

 the tongue anterior to 

 this fold is of mandibular 

 (buccal) origin, while the 

 part behind it comes from 

 the pharynx. The sur- 

 face of the former is sup- 

 plied by the mandibular 

 nerve, the third division 

 of the fifth, and the latter by the glosso-pharyngeal. The mucous membrane of the 

 posterior third does not bear papillae (except the circumvallate papillae near the junc- 

 tion of the two regions), but is rich in adenoid tissue and glands, differing in both 

 respects from the part in front of it. The arrangement of the transverse fibres of the 

 glosso-palati muscles in the substance of the tongue suggests a sphincter at the 

 entrance of the pharynx. Finally, in deglutition it is in passing this line that the 

 bolus ceases to be under the control of the will. 



99 



Fig. 1328. 



Fibres of azygos uvulae 



Pharyngeal mucous membrane 



Fibres of 

 p>alato-pharyngeus 



Masses of glands 



Glands 



Oral mucous membrane 



Transverse section of soft palate near base of uvula. X 4- 



