GESTURES NERVES OF THE FACE. 



497 



portio dura of the seventh pair in the ass, and on both sides instead of 

 one, as done by Sir Charles Bell, Mr. Mayo found, that the nerve pre- 

 sides over simple voluntary motion only ; and by a similar division of 

 the second and third branches of the fifth, at their points of con- 

 vergence, he showed, that the lips were deprived of sensation, not 

 of motion. "No doubt, I believe," says Mr. Mayo, "is now enter- 

 tained, that the inference which I drew from these experiments is 

 correct ; namely, that the portio dura of the seventh pair is a simple 

 voluntary nerve, and that the facial branches of the fifth are exclusively 

 sentient nerves." In the prosecution of his inquiries, Mr. Mayo ob- 



Fig. 203. 



Plan of the Branches of the Fifth Nerve, modified from a sketch by Sir C. Bell. 



tt. Submaxillary gland, with the submaxillary ganglion above it. 1. Small root of the fifth nerve, 

 Which joins the lower maxillary division. 2. Larger root, with the Gasserian ganglion. 3. Oph- 

 thalmic nerve. 4. Upper maxillary nerve, 5. Lower maxillary nerve. 6. Chorda tympani. 7. Facial 

 nerve. 



served, that the masseter muscle, temporal, pterygoids, and circumflexus 

 palati receive no branches from any nerve except the fifth, and yet that 

 they receive no twigs from the ganglionic portion of the nerve; and 

 thence he concludes, that almost all the branches of the large or gan- 

 glionic portion of the fifth pair are nerves of sensation, whilst those of 

 the small fasciculus or ganglionless portion are nerves of motion. This 

 smaller portion of the fifth pair issues from the peduncles of the brain ; 

 constitutes a gangliform plexus with the inferior maxillary only; pre- 

 sents the common aspect of most nerves of the body, and is distributed 

 to the chief muscles concerned in the process of mastication. Hence 

 VOL. i. 32 



