Download PowerPoint on spinal cord and grey/white matter

Spinal Cord as part of the
Nervous System plus
Grey & White matter
Already know the reflex arc
A few more parts to add
Gray and White Matter of the CNS
(GROSS ANATOMY OF THE CNS)
 Gray matter: gray-colored
 Where neuron cell bodies are clustered
 White matter: white-colored
 Where millions of axons are running between
different part of CNS, in bundles of “tracts”
 Remember, tracts are in CNS, vs nerves in PNS
 White is from the myelin sheaths
Usual pattern of gray/white in CNS
 White exterior to gray __________________
 Gray surrounds hollow
central cavity ______________________________
 Two regions with additional
gray called “cortex”
______________
 Cerebrum: “cerebral cortex”
 Cerebellum: “cerebellar cortex”
(pic from Marieb lab book p 263)
Gray/White in spinal cord
 Hollow central cavity (“central
canal”)
 Gray matter surrounds cavity
 White matter surrounds gray
matter (white: ascending and
descending tracts of axons)
 “H” shaped on cross section
 Dorsal half of “H”: cell bodies of
interneurons
 Ventral half of “H”: cell bodies of
motor neurons
 No cortex
Same pattern
Dorsal (posterior)
white
gray
Central canal_____
Ventral (anterior)
Spinal cord cross section
Grey Matter vs White Matter
1. Grey matter is made up of nerve cell bodies while white matter is made up of fibers.
2. Unlike the white matter, the neurons of grey matter do NOT have extended axons.
3. Grey matter occupies 40 percent of the brain, while white matter fills 60 percent of
the brain.
4. Grey matter has this color because of the grey nuclei that comprises the cells. Myelin
is responsible for the white appearance of the white matter.
5. Grey matter has NO myelin sheath, while white matter is myelinated.
6. Processing is concluded in the grey matter, while white matter allows
communication to and from grey matter areas, and between the grey matter and the
other parts of the body.
Basic neuronal
organization
Anterior view
 Coronal section
of cerebrum
 Cross sections
of spinal cord
and brains stem
 Note gray
matter (brown)
and white
matter (tan)
 Reflex arc and
information
processing are
shown