FACIAL NERVE. 



551 



filaments of origin of the facial have long been recognized. They are in 

 brief as follows : When there is a lesion of the brain-substance anterior to 

 the pons Varolii, the phenomena due to paralysis of the facial are observed 

 upon the same side as the hemiplegia, opposite the side of injury to the brain. 

 When the lesion is either in the pons or below it, the face is affected upon 

 the same side, and 

 not upon the side 

 of the hemiplegia. 

 This is called alter- 

 nate paralysis. In 

 view of these facts, 

 the phenomenon of 

 hemiplegia upon 

 one side and facial 

 paralysis upon the 

 other is regarded 

 as indicating, with 

 tolerable certainty, 

 that the injury to 

 the brain has oc- 

 curred upon the 

 same side as the 

 facial paralysis, 

 either within or 

 posterior to the 

 pons Varolii. 



As already stat- 

 ed, the fibres of or- 

 igin of the facial 

 have been traced to 

 the floor of the 

 fourth ventricle, 

 where a few decus- 

 sate but most of 

 them are lost. The 

 question now is, 

 whether or not the 



FIG. 199. Superficial branches of the facial and the fifth (Hirschfeld). 

 1, trunk of the facial ; 2, posterior auricular nerve ; 3, branch which it re" 

 cei,ves from the cervical plexus ; 4, occipital branch ; 5, 6, branches to the 

 muscles of the ear; 7, digastric branches; 8, branch to the atylo-hyoid 

 muscle ; 9, superior terminal branch ; 10, temporal branches ; 11, frontal 

 branches ; 12, branches to the orbicularis palpebrarum ; 13, nasal, or sub- 

 orbital branches ; 14, buccal branches ; 15, inferior terminal branch ; 16, 

 mental branches ; 17, cervical branches ; 18, superficial temporal nerve 

 (branch of the fifth) ; 19, 20, frontal nerves (branches of the fifth) : 21, 22, 

 23, 24, 25, 26, 27, branches of the fifth ; 28, 29, 30, 31, 32, branches of the cer- 

 vical nerves. 



fibres pass up through the pons and decussate above, as the pathological facts 

 just noted would seem to indicate. Anatomical researches upon this point 

 are not satisfactory, and the existence of such a decussation has never been 

 clearly demonstrated. The pathological observations, nevertheless, remain ; 

 and however indefinite anatomical researches may have been, there can be 

 no doubt that lesions in one lateral half of the pons affect the facial upon 

 the same side, while lesions above have a crossed action. The most that can 

 be said upon this point is that it is a reasonable inference from pathological 

 facts that the nerves -decussate anterior to the pons. 



