AFFERENT, OR SENSORY PATHS. 389 



(2) The impulses run to the cerebellum, by the indirect course, 

 through the descending root, and the external arcuate fibers in 

 the restiform body. They thus reach the cerebellar cortex. They 

 may excite in the cerebellum impulses of equilibrium and then 

 continue upward. From the cerebellum the course of the impul- 

 ses is, presumably, through the brachium conjunctivum to the 

 red nucleus and thalamus of both sides and thence to the cortex. 



Impulses, believed to be concerned with reflexes, run from the 

 vestibular nuclei in the floor of the fourth ventricle, (a) to the oppo- 

 site nuclei of motor cerebral nerves via the medial longitudinal 

 bundle; (b) to the quadrigeminal colliculi through the superior 

 fillet; (c) to the cerebellum by way of the descending root and 

 arcuate fibers, whence they reach the spinal nerves through the 

 descending anterior cerebello-spinal tract; (d) to the spinal cord 

 and nerves through the axones of Deiters's nucleus; and, perhaps, 

 less directly through the vestibulo-olivary and olivo-spinal fibers 

 of Kolliker. 



The Gustatory Paths. They extend from the tongue to the 

 nucleus tractus solitarii in the medulla and thence, probably, 

 through the opposite formatio reticularis and internal capsule 

 to the taste area in the gyrus fusiformis (Mills) or gyrus cinguli 

 (Flechsig). There are two paths from the tongue to the nucleus 

 of the solitary tract. Those impulses from the base of the tongue 

 and the palate run through the ninth nerve and those from the 

 anterior two- thirds of the tongue through the chorda tympani 

 and intermediate nerve to the medulla (A. F. Dixon, Keen and 

 Spiller, H. Gushing, etc.). Possibly, gustatory impulses origin- 

 ating in the palate may traverse the descending branches of 

 Meckel's ganglion and the great superficial petrosal nerve to reach 

 the geniculate ganglion on the facial; and, then, continue through 

 the intermediate nerve to the solitary tract. All impulses arriving 

 at this nucleus of the solitary tract probably complete their journey 

 in two stages : First, through the formatio reticularis to the oppo- 

 site thalamus; and, second, through internal capsule to the cortex. 



Destruction of the olfactory conduction path on one side 

 causes anosmia on the same side; of the optic tract or radiation, 

 atrophy and destruction in the corresponding halves of both retinae ; 



