THE MEDULLA OBLONGATA. 



375 



Into this anterior part of the center pass fibers of the glosso-pharyngeal nerve, 

 The greater part of this nerve, however, comes from its descending root (see 

 below). We have learned, then, two nnclei for the vagus: a ventral one, 

 which from its position (in the prolongation of the ventral horn) and from 

 the appearance of its cells (multipolar with axis-cylinders passing directly 

 into the nerve) is motor; and a dorsal one, which, lying in the prolongation 

 of the gray matter of the base of the posterior horn, is also, by its structure, 

 characterized as sensory. The first of these nuclei is designated nucleus 

 ambiguus. The fibers to which it gives origin pass, all of them, dorsally, 



Kg. 239.— Section through tlie bulb at the level of the exit of the vagus 

 (schematic). Mot. Tagus, etc., Kern, Nucleus of motor vagus, etc. Seitenhorn, 

 Lateral horn. Yorderhnrnrest, Remnant of anterior horri. Seitenstrangkern, 

 Nucleus of lateral column. Scnieifenfasern, Fibers of fillet. OUven Zwisch. 

 ScMcJit, Interolivary laj'er. For other terms see Fig. 238. 



and, bending to form a knee, Join the much coarser fibers of the sensory root, 

 which pass out straight (Fig. 339). Besides these two nuclei, the vagus re- 

 ceives fibers from at least two other places. From the upper cervical cord 

 downward one may see a fine column, which may be traced upward to the 

 oblongata, to the place where the last glosso-pharyngeal root emerges. On 

 its median side lies a column of gelatinous matter, in which cells are 



