278 SPLANCHNOLOGY. 



borders. Its superior border is attached to the palatine arch, 

 and is continuous -with the hard palate, whence the velum passes 

 downwards and backwards. The lateral borders are united to 

 the line of demarcation between the cavity of the mouth and that 

 of the pharynx. The inferior border is concave and free, resting 

 upon, and closely embracing the base of the epiglottis. From 

 ihe extremities of this border, two very thin prolongations run 

 along the lateral walls of the pharynx as far as the beginning of 

 the oesophagus ; these are the posterior pillars of the fauces. 

 Between the free border of the velum pendulum palati and base 

 of the epiglottis is the posterior opening of the mouth, called the 

 isthmus faucium, which in the horse, from the extreme develop- 

 ment of the soft palate, is constantly shut, except during the 

 passage of food or water. It is owing to the great size of the 

 velum that a horse is unable to breathe through his mouth. 

 The anterior surface of the velum forms the posterior boundary 

 of the mouth, is marked by longitudinal folds and transverse 

 lines, and studded with the mouthlets of numerous submucous 

 glands. This surface is united laterally to the base of the 

 tongue by large mucous columns, the posterior pillars of the 

 tongue, or anterior pillars of the fauces. Behind these are two 

 lateral triangular spaces, the tonsilar spaces, which take the 

 place of the tonsils or amygdalce, these being absent in the horse ; 

 numerous gland ducts open in these spaces. The posterior sur- 

 face of the soft palate is convex, and forms the anterior wall of 

 the pharynx ; it presents three very small longitudinal ridges. 



MUSCLES OF THE SOFT PALATE. 



A strong layer of aponeurosis or fibrous tissue, the staphyline 

 aponeurosis, forms as it were the foundation of the soft palate, 

 being attached above to the palatine arch. The following 

 muscles control the soft palate : 



Tensor palati. 

 Levator palati. 



Phary ngo-staphy linus. 

 Palato- staphy linus. 



Palato-glossus. 



TENSOR PALATI. 



(Peristaphylinus Externus. ) 



(Fro. 90. i.) 



A long slender muscle with tendinous extremities, running 

 longitudinally between the levator palati and the pterygoidei. It 



