THE BRAIN. 523 



are connected with the sense of taste ; some look upon it as a part 

 of the fifth, some as a part of the seventh, and still others as a 

 part of the ninth or glossopharyngeal. 



Auditory. The auditory nerve has its apparent origin from the 

 lower border of the pons, in the groove between the olivary and 

 restiform bodies. Its real origin is in the floor of the fourth 

 ventricle. As already stated, the auditory nerve enters the in- 

 ternal auditory meatus with the facial nerve. It is distributed to 

 the internal ear, and is the special nerve of the sense of hearing. 

 It will further be discussed in connection with that special sense. 



Glossopharyngeal. The superficial origin of the glossopharyn- 

 geal nerve is from the upper part of the medulla, in the groove 

 between the olivary and restiform bodies. Its real origin is a 

 nucleus in the lower part of the floor of the fourth ventricle. 

 It escapes from the cranium through the jugular foramen, together 

 with the pneumogastric and spinal accessory nerves. Its branches 

 of communication are with the pneumogastric, facial, and sympa- 

 thetic nerves. The glossopharyngeal gives off the tympanic 

 branch, the nerve of Jacobson, which is distributed to the fenestra 

 rotunda, the fenestra ovalis, and the lining membrane of the tym- 

 panum and Eustachian tube. As its name implies, the glosso- 

 pharyngeal is distributed to the tongue and pharynx. The glossal 

 portion supplies the mucous membrane of the posterior third of 

 the tongue, the tonsils, and the pillars of the fauces and soft 

 palate, while the pharyngeal portion is distributed to the pharyn- 

 geal mucous membrane and to the muscles concerned in a part of 

 the act of deglutition namely, the styloglossus, digastric, and 

 stylopharyngeus, and the superior and middle constrictors. 



Physiologic Properties. The sensibility of the parts to which 

 the glossopharyngeal nerve is distributed is due to this nerve. 

 It is also a nerve of special sense, supplying the posterior third 

 of the tongue and the palate with the sense of taste ; and, finally, 

 it is the motor nerve for the muscles enumerated which are con- 

 cerned in passing the food from the back of the mouth into and 

 through the pharynx to the esophagus in the act of deglutition. 



Vagus. This nerve is also called pneumogastric, from two of 

 the important organs, the lungs and stomach, to which it is dis- 

 tributed. Its apparent origin is by eight or ten filaments from 

 the groove below the glossopharyngeal, while its deep origin is 

 from a nucleus in the floor of the fourth ventricle, below and con- 

 tinuous with that of the same nerve. 



At the jugular foramen, by which it escapes from the cranium, 

 is found the ganglion of the pneumogastric or the jugular ganglion. 

 The pneumogastric receives branches from the spinal accessory, 

 facial, hypoglossal, and anterior branches of the first and second 

 cervical nerves. It assists in forming the pharyngeal, laryngeal, 

 pulmonary, and esophageal plexuses. Among its important 

 branches are the superior and inferior laryngeal nerves, the cardiac 



