Matter Flashcards
Gray matter is what?
Appears gray because it consist primarily of neuron cell bodies that cluster to form the nuclei and ganglia of the CNS and PNS.
White matter is what?
White matter is composed of axons that cluster to form pathways. These axons project from cell bodies in one brain region to synapse on neurons in another brain region.
White matter forms subcortical axon pathways between different regions of the cerebral cortex and also forms the pathways leading into and out of the cerebral cortex.
Projection fibers
Are axons that extend between different neural centers.
Axons traveling into or out of the cerebral cortex. These axons are compressed in the region of the thalamas and basal ganglia and fan out in a region just beneath the cerbral cortex.
Commissural Fibers
Axons that cross midline and synapse contralaterally.
Coordinate activities between the left and right hemispheres.
Association Fibers
Axons projecting between ipsilateral cortical areas.
Corona Radiata
A region of loosely pack axons of projection fibers just beneath the cerebral cortex in the region of the thalamus and hypothalamus.
Internal Capsule
The densley packed region of axons adjacent to the thalamus and/or basal ganglia
4 major groups of Commissural fibers
Corpus Collosum (the biggest)
Anterior Commissure
Posterior Commissure
Hippocampal Commissure
Nerocortex
Coritical areas having 6 laminated layers
Paleocortex
Cortical areas having less than 6 laminated layers
Archicortex
Cortical areas only having 3 laminated areas.
Layers I and II
Primary composed of axons and synapses, serving to intergrate activating whithin a vertical column formed by cortical axons.
Layer IV
Input to the cortex synapses on neurons. THIS IS THE ONLY INPUT
Layer V
Cortical neurons that project principally to nuclei of the brainstem to spinal cord. Can possibly include layer III too.
Layer VI
Cell bodies in VI have axons that mostly project to the thalamus.
