on the Structure, Distribution, and Functions of' the Nerves. 45 



Mr. Bell confines himself more immediately to the nerves of 

 the face; for the human countenance performs many functions, 

 and in it are combined the organs of mastication, of breathing, 

 of natural voice and speech, and of expression. The nerves 

 upon which these functions are dependent are here distinct, 

 and run apart from each other, until they meet at their ex- 

 tremities: they moreover take different courses through the 

 bones of the head, and therefore render the results of any ex- 

 periments which may be made upon them more certain and 

 determinate. 



The nerves of the face are the trigeminus or the Jifth of 

 Willis, and the portio dura of the seventh, which in this paper 

 is called the respiratory nerve of the face. 



The existence of the former is constant in all animals which 

 have a stomach with palpi or tentacula to embrace their food. 

 If a feeler of any kind, having no connexion with respiration, 

 projects from the head of an animal, as in the instance of the 

 antenna of the lobster, it possesses sensibility by being sup- 

 plied with a branch from this nerve : whereas, should it be 

 connected with respiration at the same time, as is the case 

 with the hollow trunk of the elephant, two nerves are readily 

 found, both of great size ; the one a continuation of the superior 

 maxillary branch of the fifth ; the other derived from the re- 

 spiratory or seventh. This nerve is subservient to the same 

 functions in the highest or most complex animals as in the 

 lowest or most simple ; being the nerve of taste, of the muscles 

 of the face and jaws, and of common sensibility; its branches 

 being distributed minutely to these organs and profusely to 

 the muscles which move the lips on the teeth. 



The portio dura only exists where there is some consent 

 established between the face and the respiratory organs. In 

 fishes there is, strictly speaking, no portio dura of the seventh, 

 the nerve resembling it being a branch of the par vagum, 

 which, instead of being distributed forward to the face, passes 

 backwards to the muscles of the gills. In the human subject 

 this nerve has a very extensive distribution, penetrating to all 

 the muscles of the face, which are also supplied with the 

 branches of the fifth pair, and to the skin in company with 

 the minute vessels of the cheek ; besides sending numerous 

 branches to the superficial muscles of the throat and neck, 

 winch are connected with branches of the spinal and respiratory 

 nerves. These two sets of nerves, moreover, of the face, differ 

 from each other as to texture ; the respiratory being found to 

 correspond with the structure of the par vagum, the filaments 

 of which are close, and like a minute plexus: whereas those of 

 the fifth are large and round, and with less intricacy in their 



texture. 



