THE KERVOUS SYSTEM. 607 



of the fibres of the ventral root (vestibular) end in cells of the lateral 

 nucleus. The cells of the median nucleus are small, those of the lateral 

 nucleus large. 



Functions. The cochlear branch is the auditory nerve proper, and 

 the vestibular is distributed to the semicircular canals, the utricule and 

 saccule, parts of the internal ear not directly concerned with hearing. 



The IXth Nerve (Glosso-Pharyngeal). 



Origin. The glosso-pharyngeal nerves (ix., fig. 364), in the enume- 

 ration of the cerebral nerves by numbers according to the position in 

 which they leave the cranium, are considered as divisions of the eighth 

 pair of nerves, the vagus and spinal accessory nerves being included with 

 them. The union of the nuclei is indeed so intimate that it will be as 

 well to take the origins of the ninth, tenth, and eleventh nerves together. 



These three nerves emerge from the bulb and spinal cord in their 

 numerical order from above downward, the bulbar portion from the lat- 

 eral aspect of the bulb in a line between the olivary and restiform bodies; 

 and the spinal portion from a line intermediate .between the anterior and 

 posterior nerve roots as far down as the sixth or seventh cervical. 



The combined glosso-pharyngeal-accessory- vagus nucleus appears to 

 consist of two parts, viz., one median or common origin, having con- 

 spicuous nerve-cells of moderate size, and three lateral origins, having 

 but few cells of small size. These are i. the nucleus amUguus, which 

 lies on the lateral side of the reticular formation and is the origin of the 

 vagus; ii. the fasciculus solitarius, situated in the bulb, ventral and a 

 little lateral to the combined nucleus, is also called the ascending root 

 of the glosso-pharyngeal nerve or the respiratory bundle ; and iii. the 

 spinal portion which takes origin from a group of cells lying in the ex- 

 treme lateral margin of the anterior cornu. This is the origin of the 

 spinal accessory; it corresponds to the antero-lateral nucleus of the bulb, 

 and the lateral part of the gray matter of the spinal cord. 



The fibres of the spinal origin of the nerve pass from these cells 

 through the lateral column to the surface of the cord. 



The fibres from the combined nucleus, chiefly from the median part, 

 pass in a ventral and lateral direction through the reticular formation, 

 then ventral to or through the gelatinous substance and strand of fibres 

 connected with the fifth nerve, to the surface of bulb. 



The fibres from the nucleus ambiguus join the combined nerve, but 

 especially the vagus. 



The bundles of fibres of the fasciculus solitarius start in the lateral 

 gray matter of the cervical cord and higher in the reticular formation 

 of the bulb, run longitudinally forward to pass into the roots of the ninth 

 nerve. 



