Gray Matter vs White Matter

Gray Matter

• non-myelinated brain matter

  • myelin: lipid insulates a nerve & inc conduction velocity

Humans have two cortices:

1. cerebral

2. cerebellar

Where is gray matter?

• cortex (cortices) = cover part of CNS

• surface of cerebrum & cerebellum

  • extends deep w/in CNS & forms nuclei body (red nucleus & basal ganglia)

What does gray matter look like?

gray/beige bc of nerve cell bodies (nuclei)

Ganglia

collections of neural cell bodies (nuclei)

Where is the ganglia?

outside of CNS/PNS

ex) dorsal root ganglia

Dorsal Root Ganglia:

contain the cell bodies of the sensory spinal nerves

White Matter

consists of myelinated fiber tracts or neuronal axons

• any collection of axons

Where is white matter?

beneath gray matter, in internal regions of the cerebrum & cerebellum

Commissure

any collection of axons (white matter) connected on one side of NS

ex) corpus callosum & pyramidal decussation