THE MOUTH. 343 



originates by a small glistening tendon, not from the palatine, but from the 

 uvular aponeurosis (Fig. 148, 7). The fascia which the two muscles form 

 is for the most part covered, in its middle portion, by the fibres of the 

 tensores palati. 



PERISTAPHYLEUS EXTERNUS. 

 (Synonyms. Tensor palati Percivall. The circumflexus of Man.) 



This is a small, elongated muscle, depressed on both sides, bulging in its 

 middle, thin and tendinous at its extremities, and extending obliquely for- 

 ward and downward from the styloid process of the temporal bone, where 

 it has its origin, to tke pterygoid trochlea. Its terminal tendon glides 

 and is inflected inwards on this pulley, to be afterwards spread out and 

 confounded with the fibrous framework of the soft palate, which causes this 

 framework to represent an expansion of the tendon. 



The muscle is covered outwardly by the pterygoidei muscles; it 

 responds, internally, to the next muscle, which separates it from the 

 Eustachian tube. 



It is a tensor and depressor of the aponeurosis of the soft palate 

 (Fig. 149, 11). 



PERISTAPHYLEUS INTERNUS. 

 (Synonyms. Stylo-gharyngeus Percivall. The levator palati of Man., 



This is formed by a pale and thin band, which originates with the 

 preceding muscle, descends between it and the Eustachian tube, passes 

 beneath the superior constrictor of the pharynx, then below the mucous 

 membrane of the pharynx to reach the soft palate, where it expands on the 

 anterior or posterior surface of the palato-pharyngeus, beneath the glandular 

 layer, its fibres becoming mixed, on the median line, with those of its fellow. 



This is an elevator of the soft palate (Fig. 149, 12). 



3. Glandular layer. This layer is comprised between the fibrous 

 membrane and the anterior mucous layer, becoming thinner as it is pro- 

 longed over the intrinsic muscles ; it does not extend to the free border of the 

 organ. It is thickest on each side of the median plane, where it forms two 

 lobes which appear on the anterior aspect of the soft palate as an elongated 

 ridge, much more marked in the Ass than the Horse. It is worthy of notice, 

 that the glandular granulations composing this layer throw all their secre- 

 tion into the mouth that is, oil the anterior face of the septum. 



4. Mucous membranes. The soft palate is covered on both its surfaces 

 by two mucous layers, one anterior, the other posterior, united, as has been 

 remarked, at the free border of the organ. The anterior is continuous, 

 above, with the mucous membrane of the hard palate; on its sides, with 

 that which covers the base of the tongue. In structure it is the same as 

 the buccal membrane; its epithelium is stratified pavement. The other 

 layer is nothing more than the pituitary membrane extended over the 

 posterior surface of the septum, and thence to the lateral surfaces of the 

 pharynx. It will be more fully described with the latter. 



5. Vessels and nerves. The soft palate is supplied with blood by the 

 accending pharyngcal and internal maxillary arteries. The nervous filaments 

 this partition receives emanate from the fifth pair of cranial nerves (superior 

 maxillary branch), and from Meckel's ganglion; they form the posterior 

 palatine nerve (Fig. 148, 8). 



FUNCTIONS. During the act of deglutition, the soft palate is raised to 



