projection fibers in the brain mainly connect what
Projection fiber The projection fibers consist of efferent and afferent fibers uniting the cortex with the lower parts of the brain and with the spinal cord. In human neuroanatomy, bundles of axons (nerve fibres) called tracts, within the brain, can be categorized by their function into association fibers, projection fibers, and commissural fibers.
White matter The total number of long range fibres within a cerebral hemisphere is 2% of the total number of cortico-cortical fibers (across cortical areas) and is roughly the same number as those that communicate between the two hemispheres in the brain's largest white tissue structure, the Corpus callosum.[4] According to SchÃ¼z and Braitenberg note "As a rough rule, the number of fibres of a certain range of lengths is inversely proportional to their length."[4]