THE CRANIAL OR ENCEPHALIC NERVES. 717 



border of the latter including also Wharton's duct, to enter the inter- 

 stice separating the genio-glossus from the hyo-glossus longus and brevis 

 muscles. From this point it continues to near the free extremity of the 

 tongue, proceeding in a very flexuous manner, and giving off, on its course, 

 divisions equally tortuous and which traverse the organ, but without 

 detaching any ramuscules to the lingual muscles ; these divisions terminate 

 in the middle and anterior portions of the lingual mucous membrane. 



Before penetrating the mass of the tongue, this nerve furnishes : 1, At, 

 and in front of, the posterior pillars of that organ, some small ramuscules 

 which are sometimes plexiform, and are distributed to the mucous 

 membrane at the base of the tongue ; 2, Lower, and behind, one or two 

 thin filaments which are carried to Wharton's duct, and ascend with it 

 to the maxillary gland ; 3, A sublingual branch, whose divisions enter the 

 gland of that name, as well as the mucous membrane covering the sides of 

 the tongue. 



The gustatory nerve receives, near its origin, the tympano-lingual filament 

 or chorda tympani a branch of the facial nerve soon to be described. Its 

 terminal divisions mix and anastomose with those of the great hypoglossal 

 nerve, in the deep muscular interstice which lodges both. 



Physiology teaches us that the gustatory nerve gives to the anterior 

 two-thirds of the lingual mucous membrane ordinary sensation, and, in 

 addition, that special sensibility (or gustatory power) by virtue of which 

 that membrane enjoys the property of appreciating savours. This is its 

 exclusive function. With regard to the tympanic filament from the facial 

 nerve, and which is joined to the gustatory, M. Bernard is of opinion that it 

 participates in the exercise of this sense of taste. Its radiating fibres extend 

 to the submucons muscular layer of which we have spoken, and on which 

 the lingual papillae rest, and endow it with the property of acting on these 

 papillae by adapting them, we may say, to the sapid substances brought into 

 contact with them. Lussana goes further than this, and, basing his state- 

 ment on observations made on Man and on experiments, asserts that the 

 nerve of the tympanum passes to the mucous membrane, and endows it with 

 the sense of taste. Vulpian. however, does not agree to either of these 

 opinions, because, according to his experience, this nerve does not go to the 

 ongue, but stops at the submaxillary ganglion. 



6. MYLO-HYOID NERVE (Fig. 336, 13). The designation of this nerve 

 ndicates its destination and uses. It goes to the muscle bearing its name, 

 nd excites its contractility ; it arises opposite to the preceding, and, like 

 ;, descends between the internal pterygoid muscle and the inferior max- 

 lary bone, adhering somewhat closely to the latter. But arriving at the 

 osterior border of the mylo-hyoideus, it passes to the outside of it, and 



neeting with the sublingual artery, ramifies on the external face of that 

 mscle. 



7. DENTAL BRANCHES (Fig. 336, 12). These are of two orders : some 

 assing to the molar, the others to the canine and incisor teeth. Their 

 .escription does not merit any special indication. 



8. MENTAL NERVES, OR TERMINAL BRANCHES OF THE INFERIOR MAXILLARY 

 ^EHVE. Perfectly analogous to the infra-orbital ramuscules, these nerves 

 3rm a fasciculus by diverging and flexuous branches, which leave the 

 aental foramen to be distributed to the textures of the lower lip, after 

 eceiving a branch from the facial nerve (Fig. 336, 11'). 



D. THE SYMPATHETIC GANGLIA ANNEXED TO THE FIFTH PAIR. These 

 janglia, joined by filaments of communication to the anterior extremity 



