202 THE ANATOMY OF THE HORSE. 



of the palate by traversing the palatine canal. It descends at the side 

 of the palate, and at the level of the corner incisor it curves in- 

 wards towards the incisor foramen, where, on the middle line, it unites 

 with the vessel of the opposite side. The single lalnal vessel resulting 

 from this union passes forwards through the incisor foramen to reach the 

 upper lip. In passing in to join its fellow at the incisor foramen, the 

 palato-labial artery runs under a small flexible bar of cartilage, which is 

 fixed to the bone by its upper extremity, while its lower extremity is 

 free. Whei-e the artery curves inwards, it detaches a branch that 

 passes downwards to be distributed in the palate below the level of the 

 incisor foramen. 



Palatine Veins. Over the whole extent of the hard palate there 

 exists a rich network of veins in the submucous connective-tissue. This 

 network is drained by a large vein which accompanies the palato-labial 

 artery as far as the lower orifice of the palatine canal. There it parts 

 company with the artery, and passes along the staphyline groove, with 

 the staphyline artery and nerve. It joins the alveolar vein. The 

 variable thickness of tlie palate depends principally on the amount of 

 blood in these veins, this being greatest in the 3'oung animal. 



The Palatine Nerve is a branch of the superior maxillary division of 

 the 5th. It emerges from the palatine canal along with the artery, 

 around which its branches interlace. It is the sensory nerve to the 

 hard palate. 



THE soft palate, Or VELUM PENDULUM PALATI. 



This is an oblique valvular curtain placed on the limit of the oral and 

 pharyngeal cavities. The oral surface of the curtain looks downwards 

 and backwards, and is covered by miicous membrane continuous with that 

 of the hard palate. The pharyngeal surface has the opposite direction, 

 and its mucoxis covering is continuous with that of the nasal chambers. 

 The anterior edge is fixed at the posterior margin of the hard palate. 

 The lateral edges are attached on the limits of the mouth and pharynx.. 

 The posterior edge is free, and extends across the root of the tongue, in 

 front of the epiglottis. The mucoiis membrane in passing between the 

 soft palate and the root of the tongue is raised on each side into 

 a fold, and two similar but less prominent ridges of mucoxis membrane 

 extend fronx the soft palate to the sides of the pharynx. These are 

 termed respectively the anterior and the posterior pillars of the soft 

 palate. Between them is a space which marks the situation of the tonsil 

 in most mammals, and into which numerous mucous glands open. The 

 soft palate of the horse is remarkable for its large size — a fact which 

 explains the difficulty with which the horse can expire or eject regurg- 

 itated matters through the mouth. 



The Isthmus of the Fauces. This is the aperture of communication 



