Download Structure of the Nervous System

Revisit Plasticity: Phineas Gage
At the center of everything… but separated by layers of
membranes
It’s all about connections…
Brain  spinal cord via foramen
magnum
 Spinal cord runs through vertebral canal,
formed by vertebral foramina

Meninges mater (umm… matter)
Dura mater – “durable” tough, dense;
protection from impact, friction
 Arachnoid mater – cushion from impact

 Subarachnoid space – CSF runs here

Pia mater – in the “pits”
 direct contact
 Carries blood vessels
 Forms nerve sheaths
 Helps form CSF
More on the pia mater

Associated with choroid plexus
 Secretes CSF
 Combination of blood vessels & neuroglia
○ Remember which kind?
Ependymal cells
It’s not all black and white… but it
is gray!

Gray matter = unmyelinated neuron cell
bodies
 Accumulate lipofuscin
 Found primarily in cortex (surface of brain)
○ Highly folded/ridged = gyri
 Increase surface area
 Small pockets of gray found in interior

White matter = myelinated axons, neuroglia
 Found in brain’s interior

In spinal cord, colors are reversed… outside
white, inside gray
Concept check!
1. Describe the three layers of the
meninges
 2. What is the function of the choroid
plexus?
 3. Describe the locations of gray and
white matter in the CNS

 Why are they those colors?
Three-Pound Marvel: The Brain

Billions of neurons, neuroglia
 Most multipolar (1 axon, many dendrites)
 Receive many signals, process them

Tracts of axons
 Information conduit  other regions of brain,
body
Forebrain: Cerebrum and
diencephalon

Largest, most anterior portion
 Emotions
 Memory
 Motor movement
 Thought

Contain basal nuclei, cerebral cortex
Basal nuclei/ganglia

4 pockets of gray matter – relay motor
information to spinal cord
 Permit coordinated, steady body movements
Cerebral cortex
Convoluted gray matter covering brain
 Large surface area (18 sq ft.)

Blood-brain barrier
Cerebral cortex nourished by vessels in
arachnoid layer
 “Barrier” exists between bloodstream
and CSF… Which neuroglia create this?

 Astrocytes!

Prevents harmful substances from
entering brain (also medications)
Cerebral Hemispheres
Halves of cerebrum divided by
longitudinal cerebral fissure
 Some division of labor…

 But you use both halves!
Communication between
hemispheres

Corpus callosum connects left and right
hemispheres
 Contributes to plasticity of brain
Four lobes of the cerebrum
Central sulcus
Lateral sulcus
Areas of specialization
Deep, medial portion

Hypothalamus, thalamus, ventricles