THE TRIGEMINUS. f>;>f> 



inosculates by a distinct twig with one of the nasal branches of the oph- 

 thalmic division. The integument of tlio 11OSO is supplied by the nasal 

 branches of tin' ophthalmic division, and also by tllOSC coming from the 

 infraorbital nerve. The upper :md lower lips arc supplied both from 

 tlu- infraorhital Mild mental nerves on t ho outside, and from the terminal 

 filaments of (he buccinator nerve on the inside; ;ind the temporal region 

 receives branches both from the superior and inferior maxillary divisions. 

 A most important, Miiastomotic branch of the fifth pair is that which its 

 inferior maxillary division sends to the facial nerve (Fig. It4,y), and 

 by means of \\hich it .supplies sensitive filaments to the great motor 

 ncrvo of the face. As a general rule, nerves which are distributed 

 exclusively to muscles receive at some part, of their origin or course 

 sensitive filaments which accompany them to their destination. The 

 muscular tissue consequently has a certain degree of sensibility ; and it, 

 is this sensibility, sometimes called the u muscular sense," \\ Inch enables 

 us to appreciate the existence and degree of contraction in any particular 

 muscle or group of muscles. Many of the sensitive filaments supplied 

 to the facial nerve by tlu 4 communicating branch of the fifth are un- 

 doubtedly destined to reach the muscles of the face \\ilh the terminal 

 branches of this nerve; but there are also abundant anastomoses be- 

 tween the facial nerve and the fifth near the final distributions of the 

 latter nerve. These anastomoses are quite numerous, between the 

 branches of the infraorbital and mental nerves and those of the facial; 

 and certain regions of the integument may, therefore, be supplied with 

 sensibility by filaments from both these sources- The observations of 

 1/Mtievant 1 have shown that ii is impossible to abolish the sensibility 

 of any extended region of the face by section of either division of tin' 

 fifth pair alone. A complete anaesthesia can only be produced by divi- 

 sion of the whole nerve within the cranial cavity. This destroys at 

 once not, only the sensibility supplied directly by the fifth pair, but also 

 that communicated to the facial by its anastomotic branch. 



According to llenle, there is still a portion of the side of the face 

 which may derive a certain degree of sensibility, apart from that due to 

 the fifth pair, from the great auricular nerve of the cervical plexus ; since 

 the anterior branch of this nerve, after supplying the under part of the 

 lobe of the ear, sends some slender filaments anteriorly to the integu- 

 ment, of the cheeks, running in some instances as far forward as the 

 neighborhood of the malar bone. 



In lli -nee of the Fifth Pair on the Special Senses The results of 



experiment show that this nerve has an important influence upon the 

 special senses, since they are always more or less interfered with, and in 

 some instances practically destroyed, by its division or injury. This 

 influence, however, is mainly not a direct but an indirect one; and shows 

 itself by a disturbance of nutrition in the tissues of the organ. For the 

 perfect action of any of the special senses, two different conditions are 



1 Trait6 des Sections Nervcuscs. Paris, 1873, p. 179. 



