554 



NERVOUS SYSTEM. 



internal ear. The fourth branch, the chorda tympani, is so important that 

 it demands special consideration. The fifth branch is given off opposite the 

 origin of the chorda tympani and passes to the pneumogastric, to which nerve 

 it probably supplies motor filaments. In this branch, sensory filaments pass 

 from the pneumogastric and constitute a part of the sensory connections of 

 the facial. 



Uses of the Chorda Tympani. This nerve passes between the bones of 

 the ear and through the tympanic cavity, to the lingual branch of the infe- 



rior maxillary division of the fifth 

 which it joins at an acute angle, be- 

 tween the pterygoid muscles. As 

 regards the portion of the facial 

 which furnishes the filaments of the 

 chorda tympani, it is nearly certain 

 that these come from the intermedi- 

 ary nerve of Wrisberg. 



There can be no doubt with re 

 gard to the influence of the chorda 

 tympani upon the sense of taste ii 

 the anterior two - thirds of the 

 tongue. In cases of disease or in- 



jury in which the root of the facial 



ia invnlvprl en flint fhp pVnrrla tvm 

 l CnorCia tym 



P ani is Paralyzed, in addition to the 



FIG. 900. Chorda-tympani nerve (Hirschf eld). 

 1, 2, 3. 4, facial nerve passing through the aquaeduc- 

 tus Fallopii ; 5, ganglioform enlargement (genie- 



ordinary phenomena of paralysis of 

 the superficial muscles of the fac 

 there is loss of taste in the anterior two-thirds of the tongue, upon the side 

 corresponding to the lesion. The action of the chorda tympani will be con- 

 sidered again, in connection with the physiology of gustation. 



Influence of Various Branches of the Facial upon the Movements of the 

 Palate and Uvula. There can be little doubt that filaments from the faciz 

 animate certain of the movements of the velum palati and uvula. It lit 

 been observed that in certain cases of facial paralysis the palate upon one 

 side is flaccid and the uvula is drawn to the opposite side ; but these phe 

 nomena do not occur unless the nerve be affected at its root or within the 

 aquaeductus Fallopii. It is true that the uvula frequently is drawn to one 

 side or the other in persons unaffected with facial paralysis, but it is none 

 the less certain that it is deviated as a consequence of paralysis of the facis 

 in some instances. The filaments of the facial which influence the levator 

 palati and azygos uvulae muscles are derived from the large petrosal branch 

 of the nerve, passing to the muscles through Meckel's ganglion, the filament 

 to the palato-glossus and the palato-pharyngeus being given off from the 

 glosso-pharyngeal, but originally coming from an anastomosing branch of 

 the facial (Longet). As regards the branches of communication from the 

 glosso-pharyngeal, Longet has mentioned a preparation by Eichet, in the 

 museum of the Ecole de medecine, of Paris, in which branches of the fack 



