13-3 Gray Matter and White Mater

Question 1

Describe the Gray matter

Answer 1

cell bodies of neurons, neuroglia, and
unmyelinated axons

Question 2

Describe the white matter

Answer 2

myelinated and unmyelinated axons

Question 3

State the horn regions in the gray matter

Answer 3

• Posterior horns—somatic and visceral sensory nuclei (incoming information from receptors)
• Anterior horns—somatic motor nuclei (outgoing information to effectors)
• Lateral horns—thoracic and lumbar segments; visceral motor nuclei

Question 4

Describe the Gray commissures

Answer 4

Gray commissures
– Narrow bands of gray matter around central
canal
– Axons cross here to the other side of spinal cord

Question 5

Describe the structural organization of the white matter

Answer 5

Three columns (regions)
* Posterior white columns—between posterior
horns and posterior median sulcus
* Anterior white columns—between anterior horns and anterior median fissure
– Anterior white commissure—where axons
cross from one side of the spinal cord to the other
* Lateral white columns—on each side of spinal cord, between anterior and posterior columns
Tract—a bundle of axons in CNS
* Relay the same type of information in the same direction
* Ascending tracts—sensory information up toward
the brain
* Descending tracts—motor commands down to the spinal cord