GLOSSOPHARYNGEAL NERVE. 703 



(Trousseau's gastric vertigo). This condition may result from irritation of the 

 vasomotor nerves of the labyrinth secondary to that of the gastric nerves, pro- 

 ducing an influence upon the pressure-relations of the endolymph. Intestinal 

 vertigo, laryngeal vertigo and urethral vertigo have been- described as occurring in 

 an analogous manner. 



IX. GLOSSOPHARYNGEAL NERVE. 



The glossopharyngeal nerve arises from three nuclei : 

 i. The sensory, gustatory nucleus, constituted of small cells, is situated near 

 the ala cinerea to the side of the hypoglossal nucleus just beneath the floor of 

 the fourth ventricle. The fibers related to this nucleus arise actually from periph- 

 eral ganglion -cells (ganglionic plexus of the lingual branch) . From these peripheral 

 ganglion-cells the cellulifugal neurites enter into contact in the gustatory nucleus ; 

 the cellulipetal dendrites are derived from the neighborhood of the sense-cells of 

 the tongue. 2. The motor nucleus is constituted of larger cells and is more 

 deeply situated. It passes without sharp limitation into the motor nucleus of the 

 vagus and sends as neurites motor fibers to the ninth and also to the tenth nerve. 

 3. The sensory, descending root is situated at the side of the solitary bundle, 

 and with it also filaments from the vagus are associated. The cells of the 

 jugular and petrosal ganglia serve for its origin ; from them neurites pass into the 

 medullary nucleus, while the dendrites are derived from the mucous membrane of 

 the pharynx. The most anterior portion of the sensory nucleus of origin is con- 

 sidered as the root of the portio intermedia of Wrisberg. 



The filaments unite to form two nerves, which subsequently coalesce, and 

 leave the medulla in front of the vagus (Fig. 241). Close to the point of exit 

 it forms the jugular ganglion, then in the petrosal fossa the petrous ganglion 

 (Fig. 246). In the jugular ganglion the nerve anastomoses with the trigeminus, 

 the facial (Fig. 243, t- and TT), the vagus (Fig. 246) and the carotid plexus. 

 From this ganglion there ascends vertically the tympanic nerve (Fig. 243, /) 

 into the tympanic cavity to unite with the tympanic plexus. This branch gives 

 sensory branches also to the tympanic cavity and the Eustachian tube. Further, 

 through the lesser superficial petrosal nerve it transmits fibers for the salivary 

 secretion of the parotid gland (in the dog) . 



Functionally, the glossopharyngeal is: i. The gustatory nerve for 

 the posterior third of the tongue, the lateral. portion of the soft palate and 

 the glossopalatine arch. 



The gustatory activity of the anterior two-thirds of the tongue has been 

 discussed in connection with the consideration of the lingual nerve and of the 

 chorda tympani. The lingual branches are provided with ganglia, principally at 

 the plexuslike points of division and at the base of the vallate papillae. The 

 terminal branches can be traced to the circumvallate papillae (Fig. 243, U), whose 

 taste-buds they surround as telodendrites. 



2. The glossopharyngeal is the motor nerve for the stylopharyngeus 

 muscle. Nevertheless, the motor fibers of origin later pass also through 

 the pharyngeal branches of the vagus. 



FIG. 246, p. 702. 



I. Diagrammatic Representation of the Distribution of the Vagus and Accessory Nerves : 10, exit of the left trunk 

 of the vagus from the cranial cavity. (101, right vagus.) 9, Glossopharyngeal nerve. 7, Facial nerve, i, 

 Deep posterior auricular branch of the facial. 2, Pharyngeal branch of the vagus. 6, Pharyngeal branch of 

 the glossopharyngeal 3, Superior laryngeal nerve, with its anastomoses (/) with the sympathetic and its 

 division (4) into the internal branch (v) and the external branch (e). 5, Inferior or recurrent laryngeal. au, 

 Auricular branch of the vagus. Cardiac nerves: g, cardiac branches from the trunk of the vagus and from 

 the superior laryngeal; i, h, the three cardiac branches from the superior (8), middle (x), and inferior (y) 

 cervical ganglia of the sympathetic, k, Ansa Vieussenii. /, Cardiac branch from the recurrent nerve L, 

 Lung with the anterior and posterior pulmonary plexuses, r, Esophageal plexus, o, o, Gastric branches of 

 the left vagus, together with the hepatic branches (). m, Celiac plexus, k, The splanchnic nerve, n, 

 Accessory nerve of Willis, which sends its inner branch into the gangliform plexus of the vagus; its outer branch 

 supplies with fibers (ac) the sternocleidomastoid muscle (Si) and (ac\) the trapezius (Cc). O, External auditory 

 canal. Oh, Hyoid bone. K, Thyroid cartilage. T, Trachea. H, Heart. P, Pulmonary artery. A, A, 

 Aorta, c, Right carotid. c\, Left carotid. 5, Right subdavian. s, Left subclavian. Z, Z, Diaphragm. 

 N, Kidney. Nn, Adrenal body. M , Stomach, m, Spleen. LI, Lung and liver. (The viscera are reduced 

 in size.) 



II. Diagrammatic Representation of the Course of the Depressor Nerve (Its origin from the Vagus is situated 

 at a higher level), as well as of the Accelerator Branch of the Sympathetic Nerve (of the cat). 



