GENERAL SOMATIC SYSTEMS OF CONDUCTION PATHS 177 



Figs. 59, 63, 64, 75, 77, 78, and 80, and in a more comprehensive 

 way in Fig. 83. 



The cortical proprioceptive pathway in its simplest form may 

 consist of a chain of only three neurons: (1) A peripheral neuron 

 whose cell body lies in some spinal ganglion, whose dendrite 

 reaches some organ of muscle sense, tendon sense, or similar 

 receptor, and whose axon terminates at the upper end of the cord 

 in the nucleus of the fasciculus gracilis or fasciculus cuneatus of 

 the same side; (2) the body of the second neuron lies in one of 

 the nuclei last mentioned (marked nucleus of dorsal funiculus in 

 Fig. 64), its axon ascends in the medial lemniscus, and termi- 

 nates in the lateral and ventral nuclei of the thalamus of the 

 opposite side (Figs. 77 and 83) ; (3) the neuron of the third order 

 lies in the thalamus and sends its axon through the internal cap- 

 sule to the somesthetic area of the cerebral cortex. 



The dorsal funiculi of the spinal cord have until recently been 

 regarded as the chief ascending pathway for all forms of sensi- 

 bility, and much of the clinical practice now in vogue is based 

 upon this assumption. But evidently such an assumption is 

 untenable. The dorsal funiculi seem to be concerned chiefly 



into the medulla oblongata, at the level of the roots of the VIII cranial 

 nerve, through the inferior colliculus, and through the thalamus. 



1. Peripheral neuron entering the dorsal funiculus and also effecting 

 intrinsic spinal reflex connections. 



2. Peripheral neuron entering the nucleus dorsalis of Clarke. 



3. Peripheral neuron effecting connections with the intrinsic correla- 

 tion neurons of the spinal cord. 



4. Peripheral motor neurons of spinal nerve. 



5. Ventral spino-cerebellar tract. 



6. Spino-olivary tract. 



7. Dorsal spino-cerebellar tract. 



8. 9. Medial lemniscus. 



10. Vestibular root fiber passing directly into the cerebellum. 



11. Vestibular root fiber entering the vestibular nucleus. 



12. Vestibulo-cerebellar tract. 



13. Olivo-cerebellar-tract. 



14. Path from the dorsal funiculus (or its nuclei) to the cerebellum. 



15. Path from the reticular formation to the cerebellum. 



16. Vestibulo-spinal tract. 



17. Path from the vestibular nucleus to the fasciculus longitudinalis 

 medialis. 



18. Path from the vestibular nucleus to the reticular formation. 



19. 20. Thalamic radiations to the cerebral cortex. 

 21. Tecto-cerebellar tract. 



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