THE FIFTH CEREBRAL NERYE. 545 



sense, from which, common sensations are conveyed through 

 the fifth nerve, and their peculiar sensation through their 

 several nerves of special sense. The muscles, also, of the 

 face and lower jaw acquire muscular sensibility through 

 the filaments of the ganglionic portion of the fifth nerve 

 distributed to them with their proper motor nerves. 



Through branches of the lesser or non-ganglionic por- 

 tion of the fifth, the muscles of mastication, namely, the 

 temporal, masseter, two pterygoid, anterior part of the 

 digastric, and mylo-hyoid, derive their motor nerves. The 

 motor function of these branches is proved by the violent 

 contraction of all the muscles of mastication in experi- 

 mental irritation of the third, or inferior maxillary, division 

 of the nerve ; by paralysis of the same muscles, when it is 

 divided or disorganized, or from any reason deprived of 

 power ; and by the retention of the power of these muscles, 

 when all those supplied by the facial nerve lose their 

 power through paralysis of that nerve. The last instance ' 

 proves best, that though the buccinator muscle gives 

 passage to, and receives some filaments from, a buccal 

 branch of the inferior division of the fifth nerve, yet it 

 derives its motor power from the facial, for it is paralyzed 

 together with the other muscles that are supplied by the 

 facial, but retains its power when the other muscles of 

 mastication are paralyzed. Whether, however, the branch of 

 the fifth nerve which is supplied to the buccinator muscle 

 is entirely sensitive, or in part motor also, must remain 

 for the present doubtful. From the fact that this muscle, 

 besides its other functions, acts in concert or harmony with 

 the muscles of mastication, in keeping the food between 

 the teeth, it might be supposed from analogy, that it 

 would have a motor branch from the same nerve that 

 supplies them. There .can be no doubt, however, that the 

 so-called buccal branch of the fifth, is, in the main, 

 sensitive ; although it is not quite certain that it may not 

 give a few motor filaments to the buccinator muscle. 



