288 THE NERVOUS SYSTEM 



stapedius. Communicating freely with the fifth, it also con- 

 tains sensory fibers, but it is in all probability insensible at 

 its root. Its section causes paralysis of the muscles which it 

 supplies, but no marked changes in sensation. The branches 

 to the otic and spheno-palatine ganglia in the aqueductus 

 Fallopii constitute their motor roots; the branch given off 

 in this situation to the tenth supplies it with motor filaments, 

 and probably also here pass sensory fibers from the tenth to 

 the seventh. In facial paralysis when the lesion is in the 

 aqueductus Fallopii or behind it, there is paralysis also of 

 the muscles of the palate and uvula, the uvula is drawn "to 

 the opposite side and there is trouble in deglutition. The 

 fibers to the azygos uvulae and levator palati pass from the 

 aqueductus Fallopii through Meckel's ganglion. 



The effect of paralysis of the facial upon the superficial 

 muscles of the face is suggested in its distribution. The 

 brow cannot be corrugated; the eye is constantly open and 

 there may be consequent inflammation from exposure ; the 

 nostril cannot be dilated, and inspiration and possibly ol fac- 

 tion are interfered with ; the cheek is flaccid ; the lips are im- 

 mobile and saliva may flow from that corner of the mouth ; 

 the buccinator is paralyzed, and there is often great diffi- 

 culty in mastication because of the accumulation of food be- 

 tween the cheek and the teeth ; the unopposed action of the 

 muscles of the opposite side greatly distort the facial fea- 

 tures, the affected side being quite expressionless. Facial 

 monoplegia is common ; facial diplegia is very uncommon. 



The Chorda Tympani. This branch of the seventh is con- 

 cerned especially in gustation. The fibers of which it is 

 composed undoubtedly come from nerve of Wrisberg. Sec- 

 tion of the seventh involving also the nerve of Wrisberg 

 causes not only facial palsy but also a loss of the sense of 

 taste in the anterior two-thirds of the tongue. The sense of 

 taste will receive later notice. 



