428 STUDIES IN ADVANCED PHYSIOLOGY. 



trolled. (6) Reflex nerves; that is, nerve fibers which by 

 a reflex action bring about the involuntary closing of the 

 eyelid, such as winking, or which cause coughing and 

 sneezing, or the involuntary movements of swallowing when 

 the soft palate is stimulated. (7) Fibers which in a reflex 

 way bring about not muscular contractions, as in number 6, 

 but secretions of saliva or tears, occasioned by the stimula- 

 tion respectively of the mucous membrane of the mouth or 

 an irritation of the conjunctiva of the eye. 



Sixth. The abducentes. The abducentes nerves arise 

 from the medulla and are distributed to the external recti of 

 the eyes controlling their movements. The sectioning of 

 this nerve causes a turning of the affected eyeball inwards. 



Seventh. The faciales. The faciales or facial nerves 

 arise on the floor of the fourth ventricle and are distributed 

 mainly to the muscles of the face. It is, therefore, almost 

 wholly a motor nerve and is of special importance from the 

 fact that it is the nerve which controls the muscles of ex- 

 pression and mimicry. 



Eighth. The acoustid. The nerves acoustici or audi- 

 tory nerves have their origin in centers in the floor of the 

 fourth ventricle of the medulla and innervate the inner ear. 

 They are sensory and carry to the brain the sensations of 

 sound. 



Ninth. The glossopharyngcah. The glossopharyngeal 

 nerves are the nerves of taste and are distributed mainly to 

 the posterior portions of the tongue. Fibers, however, 

 reach the tip of the tongue as well, which fibers are be- 

 lieved by some physiologists to cause the sensation of bitter 

 at this point. The sensations of sweet and sour are by 

 these same investigators referred to the trigeminal nerve. 

 On the back of the tongue, however, the glossopharyn- 

 geal nerves are able to carry sensations of sweet and sour 

 as well. They also innervate the mucous membrane of the 

 back of the nose and the pharynx. They contain a few mo- 

 tor fibers for certain muscles of the pharynx, and send to the 



