6o6 THE GLOSSOPHARYNGEAL NERVE. 



monly in the same direction as the subjective sense of movement." It is sometimes due to a 

 want of harmony between the impressions derived from different sense-organs or "contra- 

 dictoriness of sensory impressions (Grainger Stewart), as is sometimes felt on ascending or 

 descending a stair, or by some persons while standing on a high tower, constituting tower or 

 clitf giddiness. One of the most remarkable conditions is that called " agoraphobia " {Bcncdikt, 

 JPcstphal). - The person can walk quite well in a narrow lane or street, but when he attempts 

 to cross a wide square, he experiences a feeling closely allied to giddiness. The giddiness of 

 sea-sickness is proverbial, while some persons get giddy with waltzing or swinging. Besides 

 occurring in Meniere's disease, it sometimes occurs in locomotor ataxia, and some cerebral and 

 cerebellar affections, including cerebral aniemia. Very distressing giddiness and headache are 

 often produced by paralysis of some of the ocular muscles, e.g., the external rectus. Defective 

 or perverted ocular impressions, as well as similar auditory impressions, may give rise to vertigo; 

 in the latter or labyrinthine form the vertigo may be very severe. Severe vertigo is often ac- 

 companied by vomiting. A hard plug of ear-wax may press on the membrana tympani and 

 cause severe giddiness. The forms of dyspeptic giddiness and the toxic forms due to the abuse 

 of alcohol, tobacco, and some other drugs are familiar examples of this condition.] 



[Tinnitus Aurium, or subjective noises in the ear, is a very common symptom in disease of 

 the ear; the noise may be continuous or discontinuous, be buzzing, singing, or rumbling in 

 character. ] 



351. IX. NERVTJSGLOSSO-PHARYNGEUS. Anatomical. -This nerve (fig. 429, 9) arises 

 from the nucleus of the same name, which consists partly of large cells (motor) and partly of 

 small cells (belonging to the gustatory fibres). The nucleus lies in the lower half of the fourth 

 ventricle, deep in the medulla oblongata, near the olive (fig. 427), and posteriorly it abuts on 

 that of the vagus. The anterior part of the central nucleus is regarded as the root of the portio 

 intermedia of the facial ( 349). The nerve also receives fibres from the vagal centres. The 

 fibres collect into two trunks, which afterwards unite and leave the medulla oblongata in front 

 of the vagus. In the fossula petrosa it has on it the petrous ganglion, from which, occasion- 

 ally, a special part on the posterior twig is separated within the skull as the ganglion of Ehren- 

 ritter. Communicating branches are sent from the petrous ganglion to the trigeminus, facial 

 ( and w), vagus and carotid plexus. From this ganglion also the tympanic nerve (a.) ascends 

 vertically in the tympanic cavity, where it unites with the tympanic plexus. This branch 

 ( 349, 4) gives sensory fibres to the tympanic cavity and the Eustachian tube ; while, in the 

 log, it also carries secretory fibres for the parotid into the small superficial petrosal nerve 

 (Heidenhain% 145). 



Function. 1. It is the nerve of taste for the posterior third of the tongue, the 

 lateral part of the soft palate, and the glosso-palatine arch (compare 422). [This 

 is denied by Gowers (p. 600).] 



The nerve of taste for the anterior two-thirds of the tongue is referred to under the lingual 

 ( 347, III., 4) and chorda tympani nerves ( 349, 4). The glossal branches are provided with 

 ganglia, especially where the nerve divides at the base of the circumvallate papillae (Remak, 

 Kbllikcr, Stirling). The nerve ends in the circumvallate papillae (fig. 429, U), and the end- 

 organs are represented by the taste bulbs ( 422). 



2. It is the sensory nerve for the posterior third of the tongue, the anterior 

 surface of the epiglottis, the tonsils, the anterior palatine arch, the soft palate, and 

 a part of the pharynx. From this nerve there may be discharged reflexly, move- 

 ments of deglutition, of the palate and pharynx, which may pass into those of 

 vomiting ( 158). These fibres, like the gustatory fibres, can excite a reflex secre- 

 tion of saliva ( 145). 



3. It is motor for the stylo-pharyngeus and middle constrictor of the pharynx 



( Volkmann) ; and, according to other observers, to the (?) glosso-palatinus (Hein) 



and the (? 1) levator veli palatini and azygos uvulae (compare Sphenopalatine 



ganglion, % 347, II.). It is doubtful whether the glosso-pharyngeal nerve is really 



a motor nerve at its origin although Meynert and others have described a motor 



nucleus or whether the motor fibres reach the nerve at the petrous ganglion, 



through the communicating branch from the facial. 



4. A twig accompanies the lingual artery ; this nerve, perhaps, is vaso-dilator for the lingual 

 blood-vessels. .,-.; 



Pathological There are no satisfactory observations on man of uncomplicated affections of 

 the glosso-pharyngeal nerve. 



352. X NERVUS VAGUS. Anatomical The nucleus from which the vagus arises 

 along with the 9th and 11th nerve is in (1) the ala cinerea in the lower half of the calamus 



