ON THE HOMOLOGIES OF THE CHORDA TYMPANI 

 IN SELACHIANS.^ 



By H. A. Green. 



With three figures in the text. 



Probably few nerves in the human body have given anat- 

 omists and morphologists more trouble than the chorda tym- 

 pani. In the first place the true course of the nerve has long 

 baffled anatomical researchers, and on the other hand any one 

 of the possible paths which these fibers may take presents pecu- 

 liar difficulties of morphological interpretation. 



It will be recalled that the posterior part of the tongue is 

 innervated by the gustatory part of the glossopharyngeus nerve, 

 while the anterior part is supplied by the hngual nerve, which 

 is composed chiefly by the lingual branch of the trigemmus, to 

 which is added the chorda tympani, and an unknown number 

 of sympathetic fibers. Without attempting to summarize at 

 this time the exceedingly diverse views which have been held 

 regarding the courses of the fibers in these nerves, and confin- 

 ing our attention to the gustatory fibers in the lingual nerve, 

 the weight of authority at the present time is clearly in favor of 

 regarding these as derived from the chorda and of denying the 

 gustatory function to any of the trigeminus roots. The lingual 

 branch of the trigeminus is, then, devoted to general sensation 

 of the tongue, while the sense of taste is mediated by glosso- 

 pharyngeal and facialis fibers. While there is some clinical 

 evidence on the other side, the weight of evidence (particularly 

 anatomical and embryological data) favors this view. 



The geniculate ganglion of the facialis being a typical 



1 Studies from the Neurological Laboratory 'of Denison University, under 

 the direction C. Judson Herrick, No XIV. 



