Chapter 5
The Central Nervous System
Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning
Outline
• Organization
• Protection
• Overview of components
–
–
–
–
–
–
–
–
Cortex
Basal nuclei
Thalamus
Hypothalamus
Limbic system
Cerebellum
Brain stem
Spinal cord
Nervous System Organization
• Central nervous system (CNS)
– Consists of brain and spinal cord
• Peripheral nervous system (PNS)
– Afferent division
• Carries information to the CNS
• Two branches
– Sympathetic
– Parasympathetic
Nervous System Organization
Functional Classes of Neurons
• Afferent neurons
– Inform CNS about
conditions in both the
external and internal
environment
• Efferent neurons
– Carry instructions
from CNS to effector
organs – muscles
and glands
• Interneurons
– Found entirely within
CNS
– Responsible for
• Integrating afferent
information and
formulating an
efferent response
• Higher mental
functions
associated with the
“mind”
Neuroglia
• Also called glial cells
• Physically, metabolically, and functionally
support interneurons
• Four major types of cells
–
–
–
–
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
• 90% of CNS cells
Astrocytes
–
–
–
–
–
–
–
Main “glue” of CNS
– holds neurons
together
Guide neurons
during fetal brain
development
Aid in establishment
of blood-brain
barrier
Important in repair
of brain injuries and
in neural scar
formation
Play role in
neurotransmitter
activity
Take up excess K+
from brain ECF
Along with other
glial cells – enhance
synapse formation
and modify synaptic
transmission
•
Neuroglia
Oligodendrogytes
•
– Form myelin sheaths
around axons in CNS
Ependymal cells
•
Microglia
– Line internal, fluid-filled – Immune defense
cavities of the CNS
cells of the CNS
– In ventricles of brain, – In resting state
help form and circulate
release low levels
cerebrospinal fluid
of growth factors
that help neurons
and other glial
cells survive and
thrive
Fig. 5-4, p. 135
Subarachnoid space of brain
Cerebrospinal fluid
Arachnoid villus
Lateral ventricle
(see next slide)
Dural sinus
Venous blood
Cerebrum
Vein
Choroid plexus of lateral ventricle
Choroid plexus of third ventricle
Third ventricle
Pia mater
Arachnoid mater
Dura mater
Cranial meninges
Cerebellum
Aperture of fourth ventricle
Choroid plexus of fourth ventricle
Spinal cord
Central canal
Brain stem
Pia mater
Arachnoid mater
Dura mater
Spinal meninges
Fourth ventricle
Subarachnoid space of spinal cord
Fig. 5-6, p. 137
Protection of CNS
•
•
•
•
Enclosed by hard, bony structures
Wrapped by three protective and nourishing membranes – meninges
– Dura mater
– Arachnoid mater
– Pia mater
Floats in cushioning fluid – cerebrospinal fluid (CSF)
– Surrounds and cushions brain and spinal cord
– Shock absorbing
– Formed primarily by choroid plexuses
Blood-brain barrier limits access of blood-borne materials into brain tissue
Right lateral
ventricle
Left lateral
ventricle
Third ventricle
Fourth ventricle
Central canal
of spinal cord
Fig. 5-5, p. 136
Blood-Brain Barrier (BBB)
• Protects brain from chemical fluctuations in blood
• Minimizes possibility that harmful blood-borne
substances might reach central nervous tissue
• Prevents certain circulating hormones that could also act
as neurotransmitters from reaching brain
• Limits use of drugs for treatment of brain and spinal cord
disorders
– Many drugs cannot penetrate BBB
– Keeps K+ low and Na+ High
• Cells joined by tight junctions
Central Nervous System
• Enables you to:
– Subconsciously regulate your internal
environment by neural means
– Experience emotions
– Voluntarily control your movements
– Be consciously aware of your own body and your
surroundings
– Engage in other higher cognitive processes such
as thought and memory
Brain Anatomy
• Brain components
– Brain stem
– Cerebellum
– Forebrain
• Diencephalon
– Hypothalamus
– Thalamus
– Cerebrum
• Basal nuclei - dystonia
• Cerebral cortex
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Brain Stem
• Critical connecting link between rest of brain and
spinal cord
• Consists of
– Medulla
– Pons
– Midbrain
• Functions
Brain Stem
– Most of cranial nerves arise from brain stem
– Neuronal clusters within brain stem control heart
and blood vessel function, respiration, and many
digestive functions
– Plays role in regulating muscle reflexes involved
in equilibrium and posture
– Reticular formation within brain stem receives
and integrates all incoming sensory synaptic input
– Centers that govern sleep are in brain stem
(evidence suggests center promoting slow-wave
sleep lies in hypothalamus)
= Motor fibers
= Sensory fibers
1. Olfactory nerve
Retina
Mucosa of
nasal cavity
Termination of fibers
of olfactory nerve
Olfactory
bulb
mnemonic
On
Old
Olympus
Towering
Top
A
Famous
Vocal
German
Viewed
Some
Hops
olfactory
optic
oculomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
spinal accessory
hypoglossal
3. Oculomotor
nerve
2. Optic
nerve
6. Abducens
nerve
4. Trigeminal
nerve
Lateral
rectus
Motor—muscles
of face and
scalp; salivary
and tear glands
5. Trochlear nerve
Sensory—face
and head
Motor—
muscles of
mastication
Sensory—
taste buds on
anterior tongue
7. Facial nerve
Fig. 5-21, p. 165
Motor—muscles of
pharynx; parotid gland
= Motor fibers
Sensory—taste buds on
posterior tongue; receptors in
pharynx and carotid sinus
= Sensory fibers
8. Vestibulocochelar Vestibular
branch
nerve
Cochlear
branch
9. Glossopharyngeal
nerve
12. Hypoglossal
nerve
11. Accessory
nerve
Cochlea,
vestibule, and
semicircular
canals of
inner ear
10. Vagus nerve
Motor—muscles of pharynx and larynx;
thoracic and abdominal organs
Tongue muscles
Muscles of larynx, pharynx,
soft palate, shoulder,
and neck
Sensory—taste buds on
tongue and pharynx; thoracic
and abdominal organs
Fig. 5-21, p. 165
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Cerebellum
• Important in balance and in planning and
executing voluntary movement
• Three different parts
– Vestibulocerebellum
• Important in maintaining balance and controls eye
movements
– Spinocerebellum
• Enhances muscle tone and coordinates skilled,
voluntary movements
– Cerebrocerebellum
• Plays role in planning and initiating voluntary activity by
providing input to cortical motor areas
• Stores procedural memories
Cerebellum
• Attached at top rear portion of brain stem
• Maintains proper position of the body in space
• Subconscious coordination of motor activity
(movement)
• Plays key role in learning skilled motor tasks
Fig. 5-20, p. 163
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Diencephalon
• Houses two brain components
– Hypothalamus
• Controls many homeostatic functions important in
maintaining stability of internal environment
– Thalamus
• Performs some primitive sensory processing
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Basal Nuclei
• Act by modifying ongoing activity in motor
pathways
• Primary functions
– Inhibiting muscle tone throughout the body
– Selecting and maintaining purposeful motor
activity while suppressing useless or unwanted
patterns of movement
– Helping monitor and coordinate slow, sustained
contractions, especially those related to posture
and support
– negative
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Thalamus
• Part of diencephalon
• Serves as “relay station” and synaptic integrating
center for processing sensory input on its way to
cerebral cortex
• Along with brain stem and cortical association
areas, important in ability to direct attention to
stimuli of interest
• Capable of crude awareness of various types of
sensation but cannot distinguish their location or
intensity
• Positive, screener
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Hypothalamus
• Brain area most involved in directly regulating internal
environment
• Functions
–
–
–
–
–
–
–
–
–
Controls body temperature
Controls thirst and urine output
Controls food intake
Controls anterior pituitary hormone secretion
Produces posterior pituitary hormones
Controls uterine contractions and milk ejection
Serves as a major ANS coordinating center
Plays role in emotional and behavioral patterns
Participates in sleep-wake cycle
Limbic System
• Includes portions of the hypothalamus and other
forebrain structures that encircle brain stem
• Responsible for
– Emotion
– Basic, inborn behavioral patterns related to
survival and perpetuation of the species
– Plays important role in motivation and learning
Frontal lobe
Cingulate gyrus
Fornix
Thalamus
Hippocampus
Temporal lobe
Amygdala
Hypothalamus
Olfactory bulb
Fig. 5-17, p. 153
Brain component
Cerebral cortex
Cerebral cortex
Basal nuclei
(lateral to thalamus)
Basal nuclei
Thalamus
(medial)
Thalamus
Hypothalamus
Hypothalamus
Cerebellum
Cerebellum
Midbrain
Brain stem
Brain stem
(midbrain, pons,
and medulla)
Pons
Medulla
Spinal cord
Table 5-2 (1), p. 140
Cerebrum
• Highly developed
• Makes up about 80% of total brain weight
(largest portion of brain)
• Inner core houses basal nuclei
• Outer surface is highly convoluted cerebral
cortex
– Highest, most complex integrating area of the
brain
– Plays key role in most sophisticated neural
functions
Cerebral Cortex
• Organized into six well-defined layers
• Layers are organized into functional vertical
columns
• Each half of cortex divided into four major lobes
–
–
–
–
Occipital
Temporal
Parietal
Frontal
Central sulcus
Frontal
lobe
Parietal
lobe
Parietooccipital
notch
Occipital
lobe
Lateral
fissure
Preoccipital
notch
Temporal
lobe
Brain stem
Cerebellum
Fig. 5-8, p. 143
Cerebral cortex
• Occipital lobe
– Carries out initial processing of visual input
• Temporal lobe
– Initial reception of sound sensation
• Parietal lobe
– Somatosensory processing
• Frontal lobe
– Responsible for
• Voluntary motor activity
• Speaking ability
• Elaboration of thought
Cerebral Cortex
• Primary motor cortex
– Located in frontal lobe
– Confers voluntary control over movement
produced by skeletal muscles
– Primarily controls muscles on the opposite side of
the body
– Motor homunculus
• Depicts location and relative amount of motor cortex
devoted to output to muscles of each body part
Fig. 5-11, p. 145
Fig. 5-10, p. 145
Cerebral Cortex
• Supplementary motor area
– Plays preparatory role in programming complex
sequences of movement
• Premotor cortex
– Important in orienting the body and arms toward a
specific target
• Posterior parietal cortex
Cerebral Cortex
• Primary areas of cortical specialization for
language
– Broca’s area
• Governs speaking ability
– Wernicke’s area
• Concerned with language comprehension
• Responsible for formulating coherent patterns of
speech
• Language disorders
– Aphasias
– Speech impediments
– Dyslexia
Supplementary motor area
Primary motor cortex
Central
sulcus
Premotor cortex
Somatosensory cortex
Posterior parietal cortex
Parietal lobe
Prefrontal association cortex
Wernicke’s area
Frontal lobe
Parietal-temporal-occipital
association cortex
Broca’s area
Primary auditory cortex
Cerebellum
Limbic association cortex
Occipital lobe
Temporal lobe
Primary visual cortex
Brain stem
Spinal cord
Fig. 5-9, p. 144
Fig. 5-9b, p. 144
Cerebral Hemispheres
Left cerebral
hemisphere
Right cerebral
hemisphere
– Excels in logical,
analytic,
sequential, and
verbal tasks
– Excels in
nonlanguage skills
• Spatial
perception and
artistic and
musical talents
• Math, language
forms,
philosophy
Longitudinal fissure
Cerebral Cortex
Schematic Linking
of Various Regions
of the Cortex
Flow of signals
Outline part 2
•
•
•
•
EEG
memory
Spinal nerves
Reflex arcs
Electroencephalogram (EEG)
• Record of postsynaptic activity in cortical
neurons
• “Brain waves”
• Three major uses
– Clinical tool in diagnosis of cerebral dysfunction
– Used in legal determination of brain death
– Used to distinguish various stages of sleep
Electroencephalogram (EEG)
Memory
• Storage of acquired knowledge for later recall
• Memory trace
– Neural change responsible for retention or storage of
knowledge
• Short-term memory
– Lasts for seconds to hours
• Long-term memory
– Retained for days to years
• Consolidation
– Process of transferring and fixing short-term memory
traces into long-term memory stores
• Working memory
– Temporarily holds and interrelates various pieces of
information relevant to a current mental task
Comparison of Long-Term and Short-Term Memory
Habituation (in Aplysia)
Sensitization (in Aplysia)
Repetitious indifferent stimulus
Strong or noxious stimulus
Decreased response
to continued stimuli
Release of serotonin from
facilitating interneuron
Cyclic AMP in
presynaptic neuron
Blockage of K+ channels in
presynaptic neuron
Increased
response
to continued
stimuli
Prolongation of action potential
in presynaptic neuron
Closing of Ca2+ channels in
presynaptic neuron
Ca2+ channels in presynaptic
neuron kept open longer
Ca2+ influx
Ca2+ influx
Output of transmitter from
presynaptic neuron
Output of transmitter from
presynaptic neuron
Postsynaptic potential in
efferent neuron
Postsynaptic potential in
efferent neuron
Reduced behavioral response
to indifferent stimuli
Enhanced behavioral
response to mild stimuli
Fig. 5-18, p. 160
Long Term Potentiation
Prolonged increase in the strength of existing synaptic
Connections in activated pathways following brief
periods of repeated stimulation
Fig. 5-19, p. 162
Presynaptic neuron
Nitric oxide
release
Glutamate
release
Ca2+
AMPA
receptor
NMDA
receptor
(increases
availability
of AMPA
receptor)
Ca2+ entry
Ca2+-dependent
second messenger
system
(brings about
nitric oxide
release)
Excitatory
postsynaptic
potentials
Postsynaptic neuron
Fig. 5-19 (1), p. 162
Sleep
• Function of sleep is unclear
• Sleep-wake cycle
– Normal cyclic variation in awareness of
surroundings
• Active process consisting of two types of sleep
characterized by different EEG patterns and
different behaviors
– Slow-wave sleep
– Paradoxical, or REM sleep
Comparison of Slow-Wave and Paradoxical Sleep
EEG
Patterns
During
Different
Types of
Sleep
Spinal Cord
• Extends from brain stem through vertebral canal
• 31 pairs of spinal nerves emerge from spinal
cord through spaces formed between arches of
adjacent vertebrae
– Named for region of vertebral column from which
they emerge
•
•
•
•
•
8 pairs cervical (neck) nerves
12 pairs thoracic (chest) nerves
5 pairs lumbar (abdominal) nerves
5 pairs sacral (pelvic) nerves
1 pair coccygeal (tailbone) nerves
Spinal Nerves
Spinal Cord
• Two vital functions
– Neuronal link between brain and PNS
– Integrating center for spinal reflexes
Reflex
• Reflex
– Any response that occurs automatically without
conscious effort
• Two types of reflexes
– Simple, or basic, reflexes
• Built-in, unlearned responses
– Acquired, or conditioned, reflexes
• Result of practice and learning
Reflex Arc
• Neural pathway involved in accomplishing reflex
activity
• Five basic components
–
–
–
–
–
Receptor
Afferent pathway
Integrating center
Efferent pathway
effector
Crossed Extensor Reflex Coupled with the
Withdrawal Reflex
Cerebrum (the right hemisphere,
At the longitudinal fissure
Between it and the left
hemisphere)
Hypothalamus
Thalamus
Pineal gland
Corpus
callosum
Optic
chiasm
Midbrain
Brain
stem
Pons
Medulla
Cerebellum
Fig. 5-7, p. 142
Fig. 5-7, p. 142
Fig. 5-11a, p. 145
Front
Left
hemisphere
Right
hemisphere
Frontal
lobe
Primary
motor
cortex
Central
sulcus
Top
view
Parietal
lobe
Somatosensory
cortex
Occipital lobe
Back
Fig. 5-11a, p. 145
Motor homunculus
Left
hemisphere
Cross-sectional view
Temporal lobe
Fig. 5-11a, p. 145
Fig. 5-12, p. 148
Sensory input
Primary sensory areas
(somatosensory, 1o visual,
1o auditory cortices)
Higher sensory areas
Association areas
Higher motor areas
Primary motor areas
Motor output
Stepped art
Fig. 5-13, p. 149
Eyes closed
Eyes open
Eyes closed
Alpha waves
Beta waves
Alpha waves
Fig. 5-14, p. 150
Right cerebral
hemisphere
Left cerebral
hemisphere
Cerebral cortex
(gray matter)
White matter
Corpus callosum
Lateral ventricles
Caudate nucleus
Basal
Putamen
nuclei
(gray
Globus pallidus
matter)
Thalamus
Third ventricle
Claustrum
Mamillary bodies
(part of hypothalamus)
Fig. 5-15a, p. 152
Fig. 5-15b, p. 152
Top
Part of the
limbic system
Corpus callosum
Cerebral cortex
Front
of
brain
Thalamus
(wall of third
ventricular cavity)
Bridge
that connects
the two halves
of the thalamus
Pineal gland
Hypothalamus
Cerebellum
Pituitary gland
Brain stem
Spinal cord
Fig. 5-16, p. 153
Table 5-3, p. 156
Habituation (in Aplysia)
Sensitization (in Aplysia)
Repetitious indifferent stimulus
Strong or noxious stimulus
Release of serotonin from
facilitating interneuron
Cyclic AMP in
presynaptic neuron
Blockage of K+ channels in
presynaptic neuron
Prolongation of action potential
in presynaptic neuron
Closing of Ca2+ channels in
presynaptic neuron
Ca2+ channels in presynaptic
neuron kept open longer
Ca2+ influx
Ca2+ influx
Output of transmitter from
presynaptic neuron
Output of transmitter from
presynaptic neuron
Postsynaptic potential in
efferent neuron
Postsynaptic potential in
efferent neuron
Reduced behavioral response
to indifferent stimuli
Enhanced behavioral
response to mild stimuli
Fig. 5-18, p. 160
Fig. 5-19, p. 162
Fig. 5-19 (1), p. 162
Presynaptic neuron
Nitric oxide
release
Glutamate
release
Ca2+
AMPA
receptor
NMDA
receptor
(increases
availability
of AMPA
receptor)
Ca2+ entry
Ca2+-dependent
second messenger
system
(brings about
nitric oxide
release)
Excitatory
postsynaptic
potentials
Postsynaptic neuron
Fig. 5-19 (1), p. 162
Fig. 5-20, p. 163
Reticular
activating
system
Cerebellum
Visual
impulses
Reticular
formation
Brain
stem
Auditory impulses
Spinal cord
Ascending
sensory tracts
Descending motor
tracts
Fig. 5-22, p. 166
Table 5-4, p. 166
Slow-wave sleep, stage 4
Paradoxical sleep
Awake, eyes open
Fig. 5-23, p. 167
Spinal cord
Dorsal root
ganglion
Spinal
nerve
Meninges
(protective
coverings)
Vertebra
Intervertebral
disk
Sympathetic
ganglion
chain
Fig. 5-24, p. 168
Cervical
cord
Thoracic
cord
Lumbar
cord
Sacral
cord
Cervical
nerves
Vertebrae
Thoracic
nerves
Lumbar
nerves
Cauda
equina
Sacral
nerves
Coccygeal
nerve
Fig. 5-25, p. 169
Cell body of
efferent neuron
Cell body of
afferent neuron
Efferent fiber
White matter
Gray matter
Interneuron
Dorsal root
Dorsal root
ganglion
From receptors
To effectors
Ventral root
Spinal nerve
Fig. 5-26, p. 170
Ascending tracts
Descending tracts
Dorsal surface
Dorsal columns:
1. Fasciculus gracilis
2. Fasciculus cuneatus
Lateral corticospinal
Dorsal spinocerebellar
Gray
matter
Rubrospinal
Ventral spinocerebellar
Ventral corticospinal
Lateral spinothalamic
Ventral spinothalamic
Vestibulospinal
Ventral surface
Fig. 5-27, p. 170
Ascending tracts
Somatosensory
area
of cerebral
cortex
Descending tracts
Thalamus
Primary
motor
cortex
1
Cerebral
cortex
slice 1
2
3
4
Midbrain
5
slice 2
Cerebellum
slice 3
Ventral
corticospinal
tract
6
Lateral
corticospinal
tract
Pons
Ventral
spinocerebellar
tract
slice 3
Medulla
slice 4
Muscle
stretch
receptor
Fasciculus
cuneatus
Spinal cord
slice 5
Pressure
receptor in skin
Spinal cord
slice 5
Spinal cord
slice 6
Fig. 5-28, p. 172
Dorsal horn (cell bodies of interneurons
on which afferent neurons terminate)
Central
canal
Lateral horn (cell bodies of autonomic
efferent nerve fibers)
Ventral horn (cell bodies of somatic
efferent neurons)
Fig. 5-29, p. 173
Axon
Myelin
sheath
Connective tissue
around the axon
Connective tissue
around the nerve
Connective tissue
around a fascicle
Blood vessels
Nerve fascicle
(many axons
bundled in
connective
tissue)
Nerve
Fig. 5-30, p. 173
= Inhibitory interneuron
= Excitatory interneuron
= Synapse
= Inhibits
= Stimulates
Thermal
pain receptor
in finger
Components of a
reflex arc
Receptor
Afferent pathway
Integrating center
Efferent pathway
Effector organs
Ascending pathway
to brain
Afferent
Pathway
Stimulus
Biceps
(flexor)
contracts
Hand
withdrawn
Efferent pathway
Triceps
(extensor)
relaxes
Integrating center
(spinal cord)
Effector
organs
Response
Fig. 5-31, p. 174
Afferent
pathway
Efferent
pathway
Efferent
pathway
Flexor
muscle
contracts
Pain
receptor
in heel
Extensor
muscle
relaxes
Injured
extremity
(effector
organ)
Response
Integrating center
(spinal cord)
Flexor
muscle
relaxes
Extensor
muscle
contracts
Opposite
extremity
(effector
organ)
Stimulus
Response
Fig. 5-32, p. 175
Neuroglia
Oligodendroglia Schwann
•Wrap
axons
to form
myelin
•One for
many
axons
•Wrap
axons
to form
myelin
•1:1 ratio
•1000’s
per long
axon
Astrocytes
Astrocytes
•Remove debris
•Control K+,pH
•Diverse
•Regulate
Neurotransmitters
•Regulation of pH
•Glial end feet
•Reactiveresponds to injury
Microglia Ependymal
•Defensive
cells
Migrate to
damaged
vessels
Epithelial
lining of
ventricles
and canals
Subarachnoid space of brain
Cerebrospinal fluid
Arachnoid villus
Lateral ventricle
(see next slide)
Dural sinus
Venous blood
Cerebrum
Vein
Choroid plexus of lateral ventricle
Choroid plexus of third ventricle
Third ventricle
Pia mater
Arachnoid mater
Dura mater
Cranial meninges
Cerebellum
Aperture of fourth ventricle
Choroid plexus of fourth ventricle
Spinal cord
Central canal
Brain stem
Pia mater
Arachnoid mater
Dura mater
Spinal meninges
Fourth ventricle
Subarachnoid space of spinal cord
Fig. 5-6, p. 137