THE FIFTH CEREBRAL NERYE. 549 



The loss of the sense of taste is no doubt chiefly due to 

 the lingual branch of the fifth nerve being a nerve of 

 special sense; partly, also, perhaps, it is due to the fact 

 that this branch supplies, in the anterior and lateral 

 parts of the tongue, a necessary condition for the proper 

 nutrition of that part. But, deferring this question until 

 the glosso-pharyngeal nerve is to be considered, it irfay be 

 observed that in some brief time after complete paralysis 

 or division of the fifth nerve, the power of all the organs 

 of the special senses may be lost ; they may lose not 

 merely their sensibility to common impressions, for which 

 they all depend directly on the fifth nerve, but also their 

 sensibility to the several peculiar impressions for the 

 reception and conduction of which they are purposely 

 constructed and supplied with special nerves besides the 

 fifth. The facts observed in these cases* can, perhaps, be 

 only explained by the influence which the fifth nerve 

 exercises on the nutritive processes in the organs of the 

 special senses. It is not unreasonable to believe, that, in 

 paralysis of the fifth nerve, their tissues may be the seats 

 of such changes as are seen in the laxity, the vascular 

 congestion, oedema, and other affections of the skin of the 

 face and other tegumentary parts which also accompany 

 the paralysis ; and that these changes, which may appear 

 unimportant when they affect external parts, are sufficient 

 to destroy that refinement of structure by which the organs 

 of the special senses are adapted to their functions. 



According to Magendie and Longet, destruction of the 

 eye ensues more quickly after division of the trunk of 

 the fifth beyond the Gasserian ganglion, or after divi- 

 sion of the ophthalmic branch, than after division of the 

 roots of the fifth between the brain and the ganglion. 



of special sense, with the exception of that portion of the tongue which 

 is supplied by its gustatory branch, is well illustrated by a valuable 

 case lately recorded by Dr. Althaus. 



* Two of the best cases are published, with analyses of others, by 

 Mr. Dixon, in the Medico- Chirurgical Transactions, vol. xxviii. 



