6 5 8 



THE NERVOUS SYSTEM 



function in the muscles which it supplies interferes with the perfect exercise 

 of the organs of the special senses. Thus, in paralysis of the facial nerve the 

 orbicularis palpebrarum being powerless, the eye remains open through the 

 unbalanced action of the levator palpebrse. The conjunctiva is thus contin- 

 ually exposed to the air and dust and is liable to repeated inflammation, 

 which may end in thickening and opacity of the cornea. 



CORPOflA QUADRIGEMINA 



FIG. 414. The Nuclei of Origin and Central Connections of the Auditory and Vestibular 



Nerve. (Cunningham.) 



The sense of taste may be weakened or wholly lost in paralysis of the 

 facial nerve, which involves the chorda tympani. This result, which has 

 been observed in many instances of disease of the facial nerve in man, appears 

 explicable on the supposition that the chorda tympani is the nerve of taste 

 to the anterior two-thirds of the tongue, its fibers being distributed with the 

 so-called gustatory or lingual branch of the fifth. Streeter has just published 

 a study of the development of the seventh and eighth nerves in which he 

 traces the chorda tympani through the pars intermedia, as shown in figure 

 413, thus settling this oft-disputed question. 



