THE ANATOMY OF GUSTATION 131 



APPENDIX I 

 THE IX NERVE 



In our description of the vagal lobes and facial lobes in fish, we have, 

 liitherto, made little reference to the glossopharyngeal lobe and 

 nerve. This lobe lies just anterior to the vagal lobe and is only to be 

 defined by the study of serial sections. The ninth or glossopharyn- 

 geal nerve is, according to the Cambridge Natural History (Fishes), 

 perhaps the most typical of all the branchial nerves ; it has a pre- 

 and post -branchial branch which enclose the hyo-brancliial cleft. 

 It has a palatine branch which extends forwards and anastomoses 

 with the corresponding branch of the seventh. 



The latest authoritative description of the taste-buds in the 

 adult human being says that " they have been identified on the 

 dorsal surface of the tongue except the mid-dorsal region on both 

 the anterior and posterior surfaces of the epiglottis on the inner 

 siu-face of the ar;yi}renoid process of the larynx on the soft palate 

 above the uvula, on the anterior pillars of the fauces, and on the 

 posterior wall of the pharynx. In fishes the taste-buds of the gill 

 region are supphed by the vagus and the glossopharyngeal. In 

 man certain parts of the vagus are distributed to the larynx and to 

 the epiglottis as welJ as to the most posterior part of the tongue and 

 innervate the taste-buds of these regions. 



The glossophar3ntigeal supplies the posterior third of the tongue, 

 including the foliate and vallate papillae and adjacent part. The 

 anterior part of the tongue is supplied by the chorda tympani of the 

 facial as we have seen above. The view that each area of taste - 

 buds has a different function accorcUng to the central connections 

 of the nerve which carries the afferent impulses to the brain is 

 strongly supported by these anatomical details. It would appear 

 that, in man, there are three areas to be considered, the true taste 

 area supplied by the facial nerve, an area on the anterior pillars of 

 the fauces and uvula supplied by the glossopharyngeal nerve which 

 controls the act of swallowing and prevents food entering the pos- 

 terior nares and an area presided over by the vagus on the posterior 

 wall of the pharynx and epiglottis which prevents food entering the 

 windpipe. 



