ANATOMICAL. I239 



regard the sensory portion (pars intermedia) of the seventh nerve as the 

 path followed by the taste fibres. 



The idea that the taste fibres reach the brain by the fifth nerve 

 roots was held so long ago as 1876 by Erb, 1 and has been strongly 

 maintained by Schiff, 2 and advocated in this country by Gowers and 

 Turner. 3 According to these observers, the taste fibres leaving the 

 lingual by the chorda tympani pass into the seventh nerve and so to 

 the geniculate ganglion. Thence they are continued into the great 

 superficial petrosal and Vidian nerves to the spleno-palatine ganglion, 

 through which they pass into the second division of the fifth nerve, 

 and so to the brain. The evidence brought forward is as follows: 

 Intracranial lesion or section of the facial nerve has no effect upon 

 taste. Section of the fifth nerve roots, on the other hand, leads to loss 

 of taste on the anterior part of the tongue (Schiff). 4 Disease of the root 

 of the fifth nerve also abolishes taste in the front of the tongue, and 

 H. Salomonsohn 5 found loss of taste subsequent to pressure of a 

 tumour upon the second division of the fifth nerve. Ferguson 6 has 

 described loss of taste in the front of the tongue, following the pressure 

 of a tumour upon the Vidian nerve. 



In favour of the idea that the taste fibres, which leave the lingual 

 nerve by the chorda tympani, reach the brain by the facial nerve (or 

 pars intermedia), we have the following observations : — Extirpation of the 

 entire Gasserian ganglion in man, and intracranial section of the second 

 and third divisions of the fifth nerve are often unaccompanied by any 

 loss of taste (MacTiffany, Krause, and Lynn Thomas). 7 In lower verte- 

 brates the seventh nerve is undoubtedly a nerve of taste (Strong). 8 

 Developmentally the sensory fibres of the chorda tympani and of the 

 great superficial petrosal nerves are a portion of the facial nerve in man 

 as in lower vertebrates. 9 



In discussing the contradictory results, as regards taste, which may 

 follow disease or section of the fifth nerve roots, Dixon 10 points out the 

 close proximity of the geniculate ganglion to the Gasserian, and of the 

 facial to the fifth nerve-roots ; he views the loss of taste which in some 

 cases follows the extirpation of the Gasserian ganglion or lesion of the 

 fifth nerve roots, as due to an inflammatory or other involvement of the 

 geniculate ganglion or of the root of the facial nerve. He draws atten- 

 tion to the strong developmental and anatomical reasons for looking 

 upon the facial nerve in man as the nerve of taste for the anterior part 

 of the tongue, and contends that by assuming a lesion of the seventh 



1 "Handbuch d. Krankh. d. periph. Nerven." 



2 Schiff, Rev. mid. de la Suisse Rom., Geneve, tome vii. p. 54. 



3 Gowers, "Diseases of the Nervous System," vol. ii. p. 224, and Turner in Allbutt's 

 "System of Medicine," 1899, vol. vi. p. 752, "Diseases of the Cranial Nerves." 



4 Neurol. Centralbl, Leipzig, 1882, S. 73. 



5 "Diss.," Berlin, 1888. 6 Med.Ncivs, Phila., Oct. 1890. 



7 MacTiffany, "Intracranial Neurectomy and Removal of the Gasserian Ganglion," 

 Ann. Surg., St. Louis, 1894; Krause, "Die Neuralgie des Trigeminus," 1890; Lynn 

 Thomas, Brit. Med. Journ., London, 1899, vol. ii., Report of Summer Meeting of British 

 Medical Association, 1899. 



8 "The Cranial Nerves of Amphibia," Journ. Morphol., Boston, 1895. 



9 His, "Die ersten Nervenbahnen beim menschlichen Embryo," ami " Die niorpholo- 

 gische Betrachtung der Kopfnerven," Arch. f. Anat. u. Entwcklngsycsch., Leipzig, 1887 ; 

 Dixon, "The Development of the Branches of the Fifth Cranial Nerve in Man," Trans, 

 Roy. Irish Acad., Dublin, 1896. . , 



10 Edin. Med. Journ., 1897, vol. i. pp. 395, 628 ; and "The Sensory Distribution of the 

 Facial Nerve in Man," Journ. Anat. and Physiol., London, 1899, vol. xxxiii. p. 171. 



