CH. XLIV.] THE CRANIAL NERVES. 629 



nucleus are sensory ; the spinal accessory portion of the combined 

 nucleus, the nucleus ambiguus and fasciculus solitarius are motor. 



The glosso-pharyngeal nerve gives filaments through its tympanic 

 branch (Jacobsen's nerve), to the fenestra ovalis and fenestra 

 rotunda, and the Eustachian tube, parts of the middle ear ; 

 also, to the carotid plexus, and through the great superficial 

 petrosal nerve, to the spheno-palatine (Meckel's) ganglion. The 

 small superficial petrosal (Jacobsen's nerve) passes to the otic 

 ganglion and thus controls the parotid secretion. The carotid 

 plexus may also connect the nerve with the spheno-palatine gang- 

 lion. Connections are also made with the sympathetic plexus on 

 the great meningeal artery by the external superficial petrosal. 

 This is important, as another possible connecting link between 

 the glosso-pharyngeal and the otic ganglion is thus provided. 

 After communicating, either within or without the cranium, 

 with the vagus, it leaves the cranium, divides into the two 

 principal divisions indicated by its name, and supplies the mucous 

 membrane of the posterior and lateral walls of the upper part 

 of the pharynx, the Eustachiau 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 roots contain motor fibres 

 to the stylo-pharyngeus, middle constrictor of pharynx, and crico- 

 thyroid muscles, and probably to the levator palati and other 

 muscles of the palate, eicept the tensor which is supplied by the 

 fifth nerve, and the other constrictors of the pharynx which are 

 supplied from the nucleus ambiguus by cranial rootlets of both 

 ninth and tenth nerves. The nerve also contains fibres concerned 

 in common sensation, and the sense fcf taste, and secretory fibres 

 for the salivary glands. 



The vagus or pneumogastric nerve has most varied functions, 

 giving branches to the pharynx, larynx, oesophagus, stomach, 

 lungs, heart, intestines, liver, and spleen. Some fibres are 

 afferent and some efferent. Most of these functions we have 

 already studied in connection with the organs just named. It 

 should be particularly noted that the principal origin of this 

 nerve is at the lower end of the ventricular floor below the 

 level of the ninth, and, like it, beneath the inferior fovca. 



The spinal accessory nerve arises by two distinct origins one 

 from a centre in the floor of the fourth ventricle, and connected 

 with the glosso-pharyngeal-vagus-nucleus ; the other, from the 

 outer side of the anterior eornu of the spinal cord as low down as 

 the fifth or sixth cervical nerve. The fibres from the two origins 



