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COORDINATION AND SENSATION 



the corpus callosum. These are known as commissural fibers (C, Fig. 

 134). The third connect the cerebrum with the parts of the nervous 

 system below, and are called projection fibers (/>, Fig. 134). 



2. In the cerebellum both association and commissural fibers are 

 found. Bands of fibers, passing upward toward the cerebrum and 

 downward toward the cord, connect this part of the brain with other 

 parts of the nervous system. 



FIG. r34. Semi-diagrammatic representation of a section through 

 the right cerebral hemisphere, showing fiber tracts. A. Association fibers. 

 C. Commissural fibers. P. Projection fibers. The cell-bodies with which the 

 fiber bundles connect are in the surface layer or cortex. 



3. In the midbrain, bulb, and spinal cord fibers are found : first, that 

 connect these parts with the cerebrum J and cerebellum above ; second, 



1 Fibers passing between the spinal cord and the cerebrum cross to opposite 

 sides most of them at the bulb, but many within the cord so that the right 

 side of the cerebrum is connected with the left side of the body, and vice versa. 

 This accounts for the observed fact that disease or accidental injury of one 

 side of the cerebrum causes loss of motion or of feeling in the opposite side of 

 the body. 



