544 THE NERVOUS SYSTEM. 



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, divi- 

 sion 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. 





