378 NERVOUS SYSTEM. 



as before described (page 347). It passes into the internal 

 auditory meatus and is distributed to the internal ear within 

 the petrous bone. 



IX. N. GLOSSOPHARYNGEUS (Fig. 156, a). -The ninth or 

 glossopharyngeal nerve takes origin (Fig. 138, IX) from the 

 side of the medulla, as described in the account of the brain. 

 Close to its origin its trunk bears a small enlargement, the 

 ganglion superius. It passes along with the tenth and 

 eleventh nerves through the jugular foramen. At its exit it 

 has a ganglionic enlargement, the ganglion petrosum; this is 

 connected by fine fibres with the ganglion nodosum (Fig. 156, 

 d} of the vagus. The glossopharyngeal (Fig. 156, a) then 

 passes craniad over the surface of the tympanic bulla (15) and 

 mediad of the digastric muscle. It continues mediad of the 

 carotid artery, and as it approaches the cranial cornu of the 

 hyoid divides into two portions, one of which passes to the 

 muscles and mucosa of the pharynx, and the other to the 

 tongue, where it is the special nerve of taste. 



X. N, VAGUS. The vagus nerve arises from the side of 

 the medulla in the manner described under the Brain (page 

 346 and Fig. 138, X}. It passes through the jugular foramen 

 along with the glossopharyngeal and accessory nerves. 



Cervical Portion of the Vagus (Fig. 156, d, d'}. In the 

 foramen, or just before entering it, it presents a ganglionic 

 enlargement, the ganglion jugulare (or "ganglion of the 

 root"), and a short distance beyond the foramen it forms a 

 second ganglion, the ganglion nodosum (d^ (or "ganglion of 

 the trunk "), which lies dorsocaudad of the superior cervical 

 sympathetic ganglion (e). The ganglia of the vagus and sym- 

 pathetic are closely bound together by connective tissue, and 

 that portion of the vagus craniad of the ganglion nodosum is 

 interconnected by a network of nervous fibres with the sym- 

 pathetic (e), hypoglossal (<), and accessory (c~) nerves. From 

 the ganglion nodosum the vagus (d'} passes caudad, closely 

 bound up with the sympathetic ; the two lie at the side of the 

 common carotid artery. Just before entering the thorax the 

 two separate, the vagus being the larger and lying ventrad of 



