THE GLOSSOPHARYNGEAL NERVE 



909 



Internal branch of 

 tup. laryngeal 



External branch of 

 sup. laryngeal 







The Tympanic Nerve (n. tympanicus; nerve of Jacobson) arises from the petrous 

 ganglion, and ascends to the tympanic cavity through a small canal on the 

 under surface of the petrous 

 portion of the temporal bone on 

 the ridge w r hich separates the 

 carotid canal from the jugular 

 fossa. In the tympanic cavity 

 it divides into branches which 

 form the tympanic plexus and 

 are contained in grooves upon 

 the surface of the promontory. 

 This plexus gives off: (1) the 

 lesser superficial petrosal nerve; 

 (2) a branch to join the greater 

 superficial petrosal nerve; and (3) 

 branches to the tympanic cavity, 

 all of which will be described in 

 connection with the anatomy of 

 the middle ear. 



The Carotid Branches (n. car- 

 oticotympanicus superior and n. 

 caroticotympanicus inferior) de- 

 scend along the trunk of the 

 internal carotid artery as far as 

 its origin, communicating with 

 the pharyngeal branch of the 

 vagus, and with branches of 

 the sympathetic. 



The Pharyngeal Branches (rami 

 pharyngei) are three or four fila- 

 ments which unite, opposite the 

 Constrictor pharyngis medius, 

 with the pharyngeal branches of 

 the vagus and sympathetic, to 

 form the pharyngeal plexus; 

 branches from this plexus per- 

 forate the muscular coat of the 

 pharynx and supply its muscles 

 and mucous membrane. 



The Muscular Branch (ramus 

 stylopharyngeus) is distributed 

 to the Stylopharyngeus. 



The Tonsillar Branches (rami 

 tonsillares} supply the palatine 

 tonsil, forming around it a plexus 

 from which filaments are dis- 

 tributed to the soft palate and 

 fauces, where they communicate 

 with the palatine nerves. 



The Lingual Branches (rami 

 linguales) are two in number; one 



supplies the papillse vallatse and the mucous membrane covering the base of the 

 tongue; the other supplies the mucous membrane and follicular glands of the 

 posterior part of the tongue, and communicates with the lingual nerve. 



FIG. 793. Course and distribution of the glossopnaryngeal, 

 vagus, and accessory nerves. 



