HANDBOOK OF PHYSIOLOGY. 



and supplies the mucous membrane of the posterior and lateral walls of 

 the upper part of the pharynx, the Eustachian tube, the arches of the 

 palate, the tonsils and their mucous membrane, and the tongue as far 

 forwards as the foramen caecum in the middle line, and to near the tip 

 at the sides and inferior part. 



Functions. The glosso-pharyngeal nerve contains some motor fibres, 

 together with those of common sensation and the sense of taste. 



1. Its motor influences are distributed to the glosso-pharyngeal, the 

 stylo-pharyngei, palato-glossi, and constrictors of the pharynx. 



Besides being (2) a nerve of common sensation in the parts which 

 it supplies, and a centripetal nerve through which impressions are con- 

 veyed to be reflected to the adjacent muscles, the glosso-pharyngeal is 

 also a nerve of special sensation; being the nerve of taste (from its 

 fibres derived from the fifth, Gowers), in all the parts of the tongue and 

 palate to which it is distributed. After many discussions, the question, 

 Which is the nerve of taste? the lingual branch of the fifth, or the 

 glosso-pharyngeal? may be most probably answered by stating that they 

 .are not themselves, strictly speaking, nerves of this special function, but 

 through their connection with the fifth nerve. For very numerous ex- 

 periments and cases have shown that when the trunk of the fifth nerve 

 is paralyzed or divided, the sense of taste is completely lost in the supe- 

 rior surface of the anterior and lateral parts of the tongue, at the back 

 of the tongue, on the soft palate and palatine arches. The loss is in- 

 stantaneous after division of the nerve; and, therefore, cannot be 

 ascribed wholly to the defective nutrition of the part, though to this, 

 perhaps, may be ascribed the more complete and general loss of the sense 

 of taste when the whole of the fifth nerve has been paralyzed. 



The Tenth or Pneumogastric Nerve. The Vagus or Par 



Vagum. 



The origin of the Vagus nerve is in the lower half of the calamus 

 scriptorius in the ala cinerea (Fig. 365). Its nucleus very probably 

 represents the cells of Clarke's posterior vesicular column of the spinal 

 cord. In origin it is closely connected with the glosso-pharyngeal, spinal 

 accessory, and the hypoglossal. 



It supplies sensory branches, which accompany the sympathetic on 

 the middle meningeal artery, and others which supply the back part of 

 the meatus and the adjoining part of the external ear. It is connected 

 with the petrous ganglion of the glosso-pharyngeal, by means of fibres 

 to its jugular ganglion; with the spinal accessory which supplies it with 

 its motor fibres for the larger and upper portion of the oesophagus, and 

 with its inhibitory fibres for the heart; also with the hypoglossal, with 

 the superior cervical ganglion of the sympathetic and with the cervical 

 plexus. 



