THE CENTRAL NERVOUS SYSTEM 



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cross the middle line below the corpora quadrigemina, and then 

 bifurcate into ascending and descending branches. The ascending 

 branches end mainly in connection with cells in the red nucleus, 

 but some of them pass on to the optic thalamus, with which cells of 

 the red nucleus are also connected. The thalamus, as we have seen, 

 is in its turn extensively connected with the cerebral cortex, and the 

 red nucleus*(by the efferent tract of Monakow) with the grey matter 

 of the cord. The descending branches of the fibres of the superior 

 peduncle, entering the reticular formation of the pons, pass down, 

 it is said, to make connection with the motor nuclei of the cranial 

 and spinal nerves. The tract of Gowers, as previously stated, 

 comes into relation with the superior peduncle, passing backwards 

 along its mesial border to the worm. Since the cortex of the 



FIG. 331. DIAGRAMMATIC HORIZONTAL SECTION OF LEFT HALF OF BRAIN TO 

 SHOW INTERNAL CAPSULE. 



cerebellum is linked to the dentate nucleus, the superior peduncle 

 affords an indirect connection between it and the cerebral cortex. 

 Through the restiform body afferent impulses pass up to the cere- 

 bellum. From the cerebellum they may proceed to the cerebrum. 

 So that the path by the restiform body, dentate nucleus, and 

 superior peduncle may form an alternative route for afferent 

 impressions ascending from the periphery to the great brain a path 

 broken by at least four relays of nerve-cells. The cerebellar hemi- 

 sphere may be connected by an efferent path through the nucleus of 

 Deiters and the descending antero-lateral tract with the motor roots 

 of the same side. Another efferent path (from the dentate nucleus) 

 may be constituted by the fibres of the superior peduncle and 

 Monakow' s bundle. 



