704 VAGUS NERVE. 



3. The glossopharyngeal is the sensory nerve for the posterior third 

 of the tongue, the anterior aspect of the epiglottis, the tonsils, the an- 

 terior palatine arches, the soft palate and a portion of the pharynx. 

 These nerves exert an inhibitory influence upon the act of deglutition 

 and that of respiration. They cause, as do likewise the gustatory fibers, 

 reflex secretion of saliva. 



4. The salivary fibers are described on p. 259. 



5. A branch accompanies the lingual artery. This is vasodilator for 

 the posterior third of the tongue. 



Definite pathological observations in man referable to pure and isolated 

 affections of the ninth nerve are wanting. 



X. VAGUS NERVE. 



The origin of the vagus in connection with that of the ninth and eleventh 

 nerves consists of: i. A sensory nucleus, constituted of small cells, situated to 

 the dorsal aspect of the hypoglossal nucleus (Fig. 241). 2. Other fibers of origin 

 arise from a solitary bundle of longitudinal fibers (Lenhossek's bundle, W. Krause's 

 respiratory bundle) situated on the outer side of the nucleus and extending down- 

 ward into the cervical enlargement of the spinal cord. 3. Finally, a motor nucleus 

 (nucleus ambiguus), situated further inward and a continuation of the anterior 

 horn of the spinal cord, gives off fibers from either side. 



The vagus leaves the medulla oblongata behind the ninth nerve (Fig. 242) 

 by means of from 10 to 15 filaments between the pyramidal and lateral columns 

 and forms at the jugular foramen the jugular ganglion, which, together with the 

 gangliform plexus, behaves like a spinal ganglion with reference to the fibers of 

 origin. Its branches contain fibers of varied function. 



The sensory meningeal branch (from the jugular ganglion), in as- 

 sociation with vasomotor fibers from the sympathetic, follows the pos- 

 terior branch of the middle meningeal artery, and also sends branches 

 to the occipital and transverse sinuses. 



In cases of marked cerebral congestion and inflammation of the dura mater 

 irritation of this branch may cause vomiting. 



The auricular branch (Fig. 246, au), from the jugular ganglion, re- 

 ceives a communication from the petrous ganglion of the ninth nerve ; 

 then, passing through the mastoid canal, it crosses the path of the facial 

 (7), which it is supposed to supply with sensory fibers. In its further 

 course, it gives sensory fibers to the posterior portion of the auditory canal 

 and the adjacent portion of the auricle. A branch passes with the posterior 

 auricular nerve of the facial, to which it gives muscle-sense fibers for the 

 muscles. 



Irritation of this branch, as by inflammation or from the presence of 

 foreign bodies in the external auditory canal, may cause vomiting. Irritation in 

 the depth of the external auditory canal in the area of innervation of the auricular 

 branch also excites reflex cough, less commonly symptoms of cardiac inhibition. 

 Finally irritation of the auricular nerve causes reflex contraction of the vessels 

 of the ear. 



The anastomotic branches of the vagus are as follows : i . A branch 

 that connects the petrous ganglion of the ninth directly with the jugular 

 ganglion of the tenth nerve. Its function is unknown. 2. Just above 

 the gangliform plexus of the vagus, the entire inner half of the accessory 

 nerve enters the trunk of the vagus. This transmits to the latter motor 

 fibers for the larynx (through the recurrent branch of the vagus), for 

 the pharynx (?) and the cervical portion of the esophagus and the 

 stomach (?), as well as the cardiac inhibitory fibers. 3. In the gangli- 



