286 A Manual of Veterinary Physiology. 



supplies the skin of the head, face, and anterior two- thirds 

 of the tongue with ordinary sensation ; it supplies the 

 muscles of the face and jaw with sensation : it is the 

 efferent nerve through which many important reflex acts 

 are produced, and it acts as a trophic or nutrient nerve to 

 many parts, such as the eye. 



Division of the superior maxillary division of the fifth in 

 the horse (Bell's experiment) prevents the animal from 

 grasping food with its lips; not for the reason that they 

 are deprived of motion, but owing to loss of sensibility 

 the animal is unaware of how to take hold of the food ; the 

 relation of the fifth to muscular movements is that it keeps 

 the muscles aware of the position of objects. As an 

 afferent nerve in reflex acts it is most important ; without 

 it there could be no closure of the eye, nor sneezing ; irrita- 

 tion of the conjunctiva would produce no tears, and no 

 saliva, or but little, would be secreted. By division of its 

 branches nutrition, taste, smell, and sight are affected. 

 The cornea becomes opaque and sloughs, not merely 

 because it is exposed to injury through the loss of reflex 

 acts, but because the fifth pair controls its nutrition. 



The fifth pair supplies the vaso-motor fibres for the 

 bloodvessels of the eye. 



Sixth Pair, or Abducens, arises from the floor of the fourth 

 ventricle, and supplies the external rectus muscle of the eye 

 with motor power. Paralysis of this muscle causes internal 

 squint. 



Seventh Pair (Portio Dura), or Facial, arises from the floor 

 of the fourth ventricle. At its origin it is exclusively motor, 

 but immediately afterwards becomes sensory and motor, • 

 through connection with the fifth, pneumogastric, and 

 glosso-pharyngeal. The facial consists of two roots, one in the 

 auditory nerve, the other the facial proper. The branches 

 of the facial nerve are the petrosal, supplying motor fibres 

 to the spheno-palatine ganglion, branches to tho otic 

 ganglion, and motor fibres to the tensor palati, tensor 

 tympani, parotid gland, and tho stapedius muscle of the 

 internal ear. The important chorda tympani passes through 



