496 



GLOSSO-PHARYNGEAL NERVE. 



described by Jacobson.* The nervus tympa- 

 nicus enters a canal in the petrous portion of 

 the temporal bone, and there anastomoses with 

 the Vidian and the carotid plexus of the sym- 

 pathetic. The orifice of this canal is placed 

 between the jugular fossa and carotid canal, 

 and external to the termination of the aqueduct 

 of the cochlea. The ramus tympamcus is 

 figured and described by Arnold f as dividing 

 into six filaments : 1. a filament to the fenestra 

 rotunda; 2. one to the fenestra oval is ; 3. one 

 which anastomoses with the sympathetic; 4. 

 one distributed upon the Eustachian tube ; 5. 

 one, which he terms nervus petrosus profundus 

 minor, anastomosing with the spheno-palatme 

 ganglion ; 6. one, the nervus petrosus superfi- 

 cialis minor, which anastomoses with a branch 

 from the otic ganglion or ganglion Arnold i. 

 The nerve of Jacobson thus forms an anasto- 

 mosis among the glosso-pharyngeal, the second 

 and third branches of the fifth pair, and the 

 superior ganglion of the sympathetic.} A small 

 branch arises from the ganglion petrosum, as 

 delineated by Arnold, which unites itself to 

 the auricular branch of the par vagum.|| 



Two other filaments are generally found con- 

 nected with that part of the trunk of the nerve 

 occupied by the ganglion petrosum. These 

 are a communicating twig between the ganglion 

 petrosum and ganglion of the par vagum, and 

 an anastomosing filament of the sympathetic. 

 As these filaments are very minute, and lie in a 

 dense fibrous sheath, they can only be displayed 

 by an exceedingly careful dissection. The 

 communicating filament between these two 

 ganglia of the glosso-pharyngeal and par vagum 

 is short, and passes directly from the one gan- 

 glion to the other. The communicating filament 

 from the sympathetic comes from the superior 

 cervical ganglion, mounts up between the 

 trunks of the par vagum and glosso-pharyngeal, 

 and divides into two portions, one of these 

 connecting itself to the ganglion petrosum, the 

 other to the ganglion of the par vagum. The 

 course and mode of termination of this com- 

 municating filament of the sympathetic is re- 

 presented differently by Wutzer^ from the de- 

 scription here given. I have adopted that 

 given by Arnold,** since it exactly agrees with 

 my own dissections. Another branch has been 

 described as arising from the ganglion petrosum 

 immediately below the ramus tympanicus, and 

 passing backwards behind the styloid process, 

 to anastomose with the trunk of the facial after 



* Acta Reg. Soc. Havniensis Medic, torn. v. 

 Copen. 1818. 



t Icones Nervorum Capitis, tab. vii. 1834. 



t Cruveilhier (Anatomie Descriptive, torn. iv. 

 p. 952, 1835) states that, in one subject he found 

 this ramus tympanicus formed by two branches, 

 one from the par vagum, the other from the glosso- 

 pharyngeal. In another subject it was formed by 

 a branch from the auricular of the pneumo-gastric 

 united with one from the glosso-pharyngeal. 



Op. cit. plates iii and v. 



|| It appears that the ramus auricularis of the 

 par vagum was described even to both its branches 

 by Comparetti, p. 129, De Aure Interna, &c. 



11 Op. cit. fig. vii. 



** Op. cit. tab. iv. 



its exit from the stylo-mastoid foramen * We 

 here see that the anatomy of that portion of the 

 glosso-pharyngeal nerve which lies within the 

 foramen lacerum is very complicated, but it 

 must be at the same time obvious that it em- 

 braces considerations of great interest in a phy- 

 siological point of view. 



What the true nature of these two ganglia is, 

 we cannot at present venture positively to de- 

 cide. I may mention, however, that Miillerf 

 states that he is satisfied, that the superior gan- 

 glion or ganglion jugulare resembles the Casse- 

 rian ganglion upon the trigeminus or fifth pair, 

 and those upon the posterior roots of the spinal 

 nerves, for while one portion of the nerve 

 swells into a ganglion, the other passes by 

 without assisting in its formation. On the 

 other hand, he believes that the inferior gan- 

 glion differs decidedly from those upon the 

 posterior roots of the spinal nerves, and resem- 

 bles the swelling which is occasionally found 

 upon a nerve where it is joined by branches 

 from the sympathetic. The ramus tympanicus, 

 according to his view, belongs to the sympa- 

 thetic system of nerves.} 



On escaping from the foramen lacerum the 

 glosso - pharyngeal occasionally forms direct 

 anastomoses with the par vagum, spinal acces- 

 sory, and superior ganglion of the sympathetic ; 

 at other times it only anastomoses with these 

 through its branches. 



Digastric and stylo-hyoid branch. The 

 origin of this branch is far from being regular. 

 It frequently arises from the external side of the 

 nerve soon after its exit from the foramen lace- 

 rum. It ramifies, as its name implies, in the 

 digastric and stylo-hyoid muscles. The fila- 

 ments of this nerve anastomose in the substance 

 of the digastric muscle with the digastric branch 

 of the portio dura. 



Carotid branches are two or more in num- 

 ber, and pass from the convexity of the nerve 

 or from some of its pharyngeal branches, and 

 proceed upon the surface of the internal carotid, 

 where they form a very evident anastomosis with 

 the sympathetic, with the pharyngeal, and other 

 branches of the par vagum, and assist in form- 

 ing the plexuses around the carotid arteries. 

 They have been traced downwards for a consi- 

 derable extent, and found to anastomose with 

 the superior and even with the middle cardiac 

 nerves. 



Pharyngeal branches. The nerve next fur- 

 nishes the pharyngeal branches, which are from 

 two to four in number. The largest of these 

 proceed downwards, and their ramifications can 

 be traced over the whole of the pharynx, but 

 more particularly over its upper and middle 



* Cruveilhier, op. cit. p. 953. He looks upon 

 this twig as the rudiment of a considerable branch 

 of the facial, which he found in one case partly to 

 replace the glosso-pharyngeal. See also torn. iii. 

 p. 424. 



t Archiv. fur Anat. &c. No. ii. 1837, p. 276. 



| Handbuch der Physiol. Erster Band. 



$ Mr. Swan, in plate xvii. Jig. 2 and 3, of his 

 " Demonstrations of the Nerves of the Human 

 Body," figures this communication as formed by a 

 filament of the digastric branch of the facial going 

 to join the trunk of the glosso-pharyngeal. 



