406 DISEASES AND INJURIES OF THE FACIAL EEGION. 



Treatment. — Eemoval of cause, cool astringent washes to 

 the mouth, and if ulcers form which have no disposition to 

 heal, the nitrate of silver is to be applied. 



PARALYSIS OF THE LIPS, 



Generally met with in horses which are compelled to wear 

 heavy bridles, as those used for hearses, mourning coaches, &c., 

 or in any class of harness-horse whose harness-bridle fits him 

 badly. It is called in Yorkshire dropped-lip ; and the term is 

 very expressive, for the lips are pendulous, the lower one semi- 

 everted, and the horse's face seemingly lengthened by this pen- 

 dulosity. They hang elongated, flaccid, and powerless; the 

 saliva flows from the mouth, in consequence of the animal being 

 unable to approximate his lips. When attempting to drink he 

 pushes his head into the water up to his eyes ; and whilst feed- 

 ing he is compelled to gather his food with his teeth only. He 

 therefore feeds from the bottom of the manger, pushing his nose 

 deeply into his corn. He champs whilst eating, often drops his 

 mouthful, and generally quids his hay. 



This affection is due to an injury to the portio dura, or seventh 

 pair of nerves. If both the nerves are injured, both sides of the 

 lips will be paralysed, causing the pendulosity already men- 

 tioned; but if the injury is limited to one nerve, as is more 

 usually the case, the lips will }>e drawn from the affected side, 

 and the horse's mouth will ap])ear crooked. 



The seventh pair of nervi;s convey the motor power to a 

 variety of muscles, but more particularly, as bearing upon the 

 subject now under consideration, to those of the lips, nose, and 

 lower part of the face. These nerves pass out of the cranium 

 by the stylo-mastoid foramen of the petrous temporal bone ; at 

 first deeply buried undei' the parotid gland, they afterwards 

 pass between tlie glands and guttural pouches, to gain the pos- 

 terior border of the lower jaw, round the neck of which they 

 turn, and, mounting to the external surface of the masseter 

 muscle, run downwards on the cheek quite subcutaneously. In 

 well-bred fine-coated horses they can be seen very plainly on 

 the sides of the cheeks, and being thus superficially situated, 

 are liable to be injured by the pressure of a heavy ill-fitting 

 bridle. The injury causes inflammation of the nerve (neuritis) 



