498 



GLOSSO-PHARYNGEAL NERVE. 



like accurate data in enabling us to judge of 

 the functions of tliis nerve. Its deep situa- 

 tion, its proximity to important parts, and the 

 consequent difficulty of exposing it in the living 

 animal, have until very lately deterred physio- 

 logists from making it an object of experimental 

 investigation. Some have supposed that it 

 supplies the nervous filaments upon which the 

 sense of taste at the root of the tongue de- 

 pends, while the third branch of the fifth pair 

 furnishes those of the anterior part of this 

 organ. Mr. Mayo* states that " when this 

 nerve is pinched in an ass recently killed, a 

 distinct convulsive action ensues, apparently 

 including and limited to the stylo-pharyngeus 

 muscle and upper part of the pharynx." Ue 

 concluded from this that the glosso-pharyngeal 

 is in part, probably, a nerve of voluntary mo- 

 tion ; and from its distribution upon the sur- 

 face at the root of the tongue, that it is also 

 partly a nerve of common sensation. Sir C. 

 Bell believes that this is the respiratory nerve 

 of the tongue and pharynx, associating the 

 movements of those organs with the muscles 

 of respiration in speech and in deglutition. 

 And we find it stated by Mr. Shaw f that its 

 power of combining the movements of the 

 tongue and pharynx in deglutition " has been 

 shown by several experiments, the results of 

 which were very curious, and corroborative of 

 the views deduced from comparative anatomy." 

 Panizza J has undertaken an experimental in- 

 vestigation into the functions of the nerve, and 

 obtained very unexpected results. 



From these we are led to believe that when 

 this nerve is pricked in a living animal, this is 

 attended by no indications of suffering and no 

 convulsive movements ; that section of both 

 nerves is followed by loss of taste, while the 

 tactile sensibility of the tongue and the mus- 

 cular movements of deglutition and mastication 

 remain unimpaired ; that section of the fifth 

 pair is on the contrary followed by loss of 

 common sensation without any apparent effect 

 upon the taste. From these and other experi- 

 ments upon the nerves supplying the tongue, 

 he concludes that the glosso-pharyngeal is the 

 nerve upon which the sense of taste depends, 

 and is therefore the true gustatory nerve. Dr. 

 M. Hall and the late Mr. Broughton had, 

 from experiments performed previous to the 

 publication of those of Panizza, arrived at the 

 conclusion that this nerve is not a nerve of com- 

 mon sensation. These gentlemen likewise 

 reported at the meeting of the British As- 

 sociation for 1836 an experiment, the results 

 of which were in exact accordance with those 

 obtained by Panizza upon this nerve, but no 

 details of these experiments have yet been pub- 



* Anatomical and Physiological Commentaries, 

 n. ii. p. 11. 1822. 



* London Medical and Physical JournaLvol. xlix. 

 1823. 



t Edinburgh Medical and Surgical Journal, Jan. 

 1836, and Medical Gazette, Sept. 1835. 



<j Fourth Report of British Scientific Association, 

 and Mr. Brou^hton, in vol. xlv. of Edinburgh Me- 

 dical and Surgical Journal. 



lished. Mr. Mayo* has stated several objec- 

 tions to these conclusions of Panizza. He rests 

 his grounds of dissent principally upon the 

 fact that the distribution of this nerve is con- 

 fined to the posterior part of the tongue; while 

 the sense of taste, he maintains, is also present in 

 the anterior part of that organ, and consequently 

 it cannot, in that part at least, depend upon the 

 glosso-pharyngeal. The persistence of the sense 

 of taste after section of the fifth pair may, Mr. 

 Mayo supposes, depend upon the palatine twigs 

 of the second branch of the fifth pair distri- 

 buted upon the palate and isthmus of the fiuicvs. 

 Mr. Mayo attempted to decide the matter by 

 experiment, but he did not carry this suffi- 

 ciently far to obtain any satisfactory results. 

 Dr. Alcockf has also lately examined into the 

 functions of this nerve experimentally, and has 

 arrived at conclusions at direct variance with 

 those of Panizza; for according to Dr. Alcock, 

 when this nerve is exposed and irritated in the 

 living animal, it excites pain and spasmodic 

 contractions of the pharynx and muscles of the 

 throat. When divided on both sides, the ani- 

 mal's taste, " to say the least of it, did not ap- 

 pear to be much affected." He believes that the 

 sense of taste enjoys " two media of percep- 

 tion, and that these are the glosso-pharyngeal 

 nerve and the lingual and palatine branches of 

 the fifth." He also states that the muscular 

 movements of deglutition are very much im- 

 paired after section of the nerve on both sides, 

 lie concludes, then, that the glosso-pharyngeal 

 are sentient nerves, and also influence muscular 

 motion. He, however, is doubtful in what 

 manner these muscular movements are excited 

 by irritation of this nerve, for though " dis- 

 posed to regard the result in question as the 

 effect of a sentient impression excited through 

 the nerve, and referred to the interior of the 

 pharynx," from the fact that this movement ex- 

 tends to muscles not supplied by this nerve, 

 and forms an associated movement, he admits 

 " that the circumstance may be as well ex- 

 plained by an exalted degree of muscular 

 excitement, or by a higher one than that ne- 

 cessary to produce die simple starting." Pro- 

 fessor MiillerJ believes that an examination of 

 the position of the ganglion jugulare will de- 

 cide that the glosso-pharyngeal is a mixed 

 nerve, and he maintains that the distribution of 

 this nerve, partly for sensation (mucous mem- 

 brane of the root of tongue), partly for the 

 movements of muscles (stylo-pharyngeus and 

 pharynx), exactly resembles that of the two 

 roots of the nervtis trigeminus. Unable amidst 

 these discordant statements to come to any sa- 

 tisfactory conclusions upon the proper func- 

 tions of this nerve, I entered into a lengthened 

 experimental and anatomical investigation for 

 this purpose. The experiments were twenty- 

 seven in number, and were performed upon as 



* Medical Gazette, Oct. 1835, and 4th edit, of 

 Outlines of Physiology, p. 314. 



t Dublin Journal of Chemical and Medical Sci- 

 ence, Nov. 1836. 



t Archiv fur Anat. und Physio], etc. n. ii. 

 1837, p. 276. 



