154 THE POCKET ANATOMY 



is inclined inwards on the middle constrictor beneath the 

 hyo-glossus to the tongue, pharynx, and tonsil. 



The jugular ganglion : the smaller of the two is situated at 

 the upper part of the groove in the temporal bone through 

 which the nerve passes. It involves only the outer side of 

 the trunk of the nerve. 



The petrous ganglion is placed in a depression on the in- 

 ferior border of the petrous bone. 



Branches : 



Connecting, from petrous ganglion : 



(a) To superior cervical ganglion of sympathetic. 



(b\ To auricular of pneumogastric. 



(c) To ganglion of root of the pneumogastric. 



Tympanic (Jacobson's nerve): arising from the petrous 

 ganglion, enters a minute canal in the bone between jugular 

 foramen and carotid canal to reach the inner wall of the 

 tympanum ; runs in a groove over the promontory, giving 

 off several branches, and, after communicating with the 

 facial, is continued forwards as the small superficial petrosal 

 nerve (vide p. 148). This nerve pierces the petrous portion of 

 the temporal to reach the middle fossa just external to the 

 hiatus Fallopii, and, passing through the petro-sphenoidal 

 suture, ends in the otic ganglion. It divides into six branches, 

 which form the tympanic plexus on the promontory. 



Three branches of communication, to the carotid plexus and 

 small deep petrosal nerve, to the great superficial petrosal 

 nerve, and to the otic ganglion respectively. 



Three branches of distribution, to thefenestraovalis, fenestra 

 rotunda, and mucous membrane of the Eustachian tube 

 respectively. 



Pharyngeal (3 or 4) : cross the internal carotid and join 

 opposite the middle constrictor with pharyngeal of pneumo- 

 gastric and sympathetic, to form pharyngeal plexus, supply- 

 ing the mucous membrane of the pharynx. 



Communicating with digastric branch of facial. 



Muscular : to stylo-pharyngeus and mucous membrane 

 of upper part of pharynx. 



Tonsillitic : to the tonsil forming plexus, the circulus ton- 

 sillaris, and thence to fauces and soft palate. 



Lingual (2) : one branch distributed to the base supplying 

 the circumvallate papillae, the other to the posterior of 

 side of the tongue. 



Special functions. Nerve of sensation to the mucous mem- 

 brane of pharynx, fauces and tonsil ; of motion to stylo- 

 pharyngeus muscle ; and of taste of the tongue. 



