MR. BELL ON THE NERVES OF THE FACE. 329 



C. The branch of the third division of the fifth nerve, which joins the plexus 

 of the portio dura before the ear. Some experimenters, ignorant of this junc- 

 tion of a sensitive nerve with the muscular nerve, have occupied themselves 

 with experiments to ascertain the degree of sensibility of the portio dura. 



D. In this figure the masseter muscle is dissected from the jaw-bone and 

 lifted up to show D, the branch of the fifth pair of nerves going into the muscle. 



E. The Ramus Buccinalis-labialis, that branch, of the fifth nerve which goes 

 to the buccinator, triangularis, levator labiorum, and orbicularis muscles. . 



F. That branch of the fifth nerve which separating from the mandibulo- 

 labralis goes to the muscles which depress the lower jaw. 



G. The suborbitary nerve, a branch of the fifth nei've. 



H. The mandibulo-labralis, a branch of the fifth nerve coming out from the 

 bone to the muscles and integuments of the lip and chin. 



I. A branch of the fifth nerve descending from the orbit. 



D, E, F, are muscular branches of the fifth nerve, and are motor nerves. 

 C, G, H, I, are sensitive branches of the same nerve which join the branches 

 of the portio dura in its universal distribution ; and although these branches 

 of the fifth enter the muscles, they possess no power over their motions. B is 

 the portio dura, which, though taking the same course with the last, is for a 

 different purpose ; while it is a motor nerve, by its association with the respi- 

 ratory nerves, it is enabled to excite those actions of the face and lips which 

 are necessarily connected with the act of breathing. 



Explanation of Plate IX. 



Fig. 1. Represents the fifth nerve dissected out and seen on its lower surface. 



A. The posterior or sensitive root before it forms the ganglion. 



B. The Gasserian ganglion. 



C. The anterior or motor root of the nerve passing the ganglion. 



D. The third or lower maxillary division of the fifth nerve. 



E. The motor portion joining the lower maxillary nerve and forming a 

 plexus with it. From this plexus go off the muscular nerves to the muscles of 

 the jaw, viz. 



1. Temporalis. 



MDCCCXXIX. 2 U 



