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Prepared by Patty Bostwick-Taylor,
Florence-Darlington Technical College
CHAPTER
7
The Nervous
System
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A. Central Nervous System (CNS)
•Regions of the Brain
• I. Cerebral hemispheres (cerebrum)
• II. Diencephalon
• III. Brain stem
• IV. Cerebellum
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A. Central Nervous System (CNS)
•Regions of the Brain
• https://www.youtube.com/watch?v=D1zkVBHPh5c
• https://www.youtube.com/watch?v=8hC6NGQReL4
• https://www.youtube.com/watch?v=vFp_qNifHzw
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Cerebral
hemisphere
Diencephalon
Cerebellum
Brain stem
Adult brain
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Figure 7.12b
I. Cerebrum
•Cerebral Hemispheres (Cerebrum)
•Paired (left and right) superior parts of the
brain
•Includes more than half of the brain mass
•The surface is made of ridges (
) and grooves (
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)
Precentral
gyrus
Central sulcus
Postcentral gyrus
Parietal lobe
Frontal lobe
Parieto-occipital
sulcus (deep)
Lateral sulcus
Occipital lobe
Temporal lobe
Cerebellum
Pons
Medulla
oblongata
Cerebral cortex
(gray matter)
Gyrus
Spinal
cord
Sulcus
Fissure
(a deep sulcus)
(a)
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Cerebral
white
matter
Figure 7.13a
I. Cerebrum
•Lobes of the cerebrum
•
(deep grooves)
divide the cerebrum into lobes
•Surface lobes of the cerebrum
•Frontal lobe
•Parietal lobe
•Occipital lobe
•Temporal lobe
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Parietal lobe
Left cerebral
hemisphere
Frontal
lobe
Occipital
lobe
Temporal
lobe
Cephalad
Caudal
(b)
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Brain
stem
Cerebellum
Figure 7.13b
I. Cerebrum
• Specialized areas of the cerebrum
•
• Receives impulses from the body’s sensory
receptors
• Located in parietal lobe
•
• Sends impulses to skeletal muscles
• Located in frontal lobe
•
• Involved in our ability to speak
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Primary motor area
Premotor area
Anterior
association area
• Working memory
and judgment
• Problem
solving
• Language
comprehension
Broca’s area
(motor speech)
Olfactory
area
Central sulcus
Primary somatic sensory
area
Gustatory area (taste)
Speech/language
(outlined by dashes)
Posterior association
area
Visual area
Auditory area
(c)
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Figure 7.13c
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Figure 7.14
I. Cerebrum
•Cerebral areas involved in
• Gustatory area (taste)
• Visual area
• Auditory area
• Olfactory area
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I. Cerebrum
•
areas of the cerebrum
• Speech/language region
• Language comprehension region
• General interpretation area
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Primary motor area
Premotor area
Anterior
association area
• Working memory
and judgment
• Problem
solving
• Language
comprehension
Broca’s area
(motor speech)
Olfactory
area
Central sulcus
Primary somatic sensory
area
Gustatory area (taste)
Speech/language
(outlined by dashes)
Posterior association
area
Visual area
Auditory area
(c)
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Figure 7.13c
I. Cerebrum
•Layers of the cerebrum
•
— outer layer
in the cerebral cortex composed mostly of
neuron cell bodies
— fiber tracts deep
•
to the gray matter
•
hemispheres
•
connects
— islands of gray
matter buried within the white matter
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Longitudinal fissure
Lateral
ventricle
Basal nuclei
(basal
ganglia)
Superior
Association fibers
Commissural fibers
(corpus callosum)
Corona
radiata
Fornix
Thalamus
Internal
capsule
Third
ventricle
Pons
Projection
fibers
Medulla oblongata
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Figure 7.15
Cerebral hemisphere
Corpus callosum
Choroid plexus of third
ventricle
Occipital lobe of
cerebral hemisphere
Thalamus
(encloses third ventricle)
Pineal gland
(part of epithalamus)
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Third ventricle
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
Cerebral peduncle
of midbrain
Fourth ventricle
Choroid plexus
Cerebellum
(a)
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Figure 7.16a
II: Diencephalon
•Sits on
of the brain stem
•Enclosed by the cerebral hemispheres
•Made of three parts
•Thalamus
•Hypothalamus
•Epithalamus
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Cerebral
hemisphere
Diencephalon
Cerebellum
Brain stem
(b) Adult brain
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Figure 7.12b
Cerebral hemisphere
Corpus callosum
Choroid plexus of third
ventricle
Occipital lobe of
cerebral hemisphere
Thalamus
(encloses third ventricle)
Pineal gland
(part of epithalamus)
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Third ventricle
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
Cerebral peduncle
of midbrain
Fourth ventricle
Choroid plexus
Cerebellum
(a)
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Figure 7.16a
Radiations
to cerebral
cortex
Visual impulses
Reticular formation
Ascending general sensory
tracts (touch, pain, temperature)
Auditory
impulses
Descending
motor projections
to spinal cord
(b)
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Figure 7.16b
II. Diencephalon
•
•Surrounds the third ventricle
•The relay station for
•Transfers impulses to the correct part of the
cortex for localization and interpretation
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II. Diencephalon
•
• Under the thalamus
• Important autonomic nervous system center
• Helps regulate body
• Controls
balance
• Regulates
• Houses the limbic center for
• Regulates the nearby
• Produces two hormones of its own
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gland
III. Diencephalon
•
•Forms the roof of the third ventricle
•Houses the
gland)
body (an endocrine
•Includes the
forms cerebrospinal fluid
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—
III. Brain Stem
•Attaches to the spinal cord
•Parts of the brain stem
•Midbrain
•Pons
•Medulla oblongata
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Cerebral hemisphere
Corpus callosum
Choroid plexus of third
ventricle
Occipital lobe of
cerebral hemisphere
Thalamus
(encloses third ventricle)
Pineal gland
(part of epithalamus)
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Third ventricle
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
Cerebral peduncle
of midbrain
Fourth ventricle
Choroid plexus
Cerebellum
(a)
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Figure 7.16a
III. Brain Stem
•
•Mostly composed of tracts of nerve fibers
•Has two bulging fiber tracts—
cerebral peduncles
•Has four rounded protrusions—
corpora quadrigemina
• Reflex centers for
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III. Brain Stem
•
•The bulging center part of the brain stem
•Mostly composed of fiber tracts
•Includes nuclei involved in the control of
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III. Brain Stem
•
• The lowest part of the brain stem
• Merges into the spinal cord
• Includes important fiber tracts
• Contains important control centers
•
•
•
•
•
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control
regulation
III. Brain Stem
•
•Diffuse mass of gray matter along the brain
stem
•Involved in motor control of
•Reticular activating system (RAS)
•plays a role in awake/sleep cycles and
© 2012 Pearson Education, Inc.
Radiations
to cerebral
cortex
Visual impulses
Reticular formation
Ascending general sensory
tracts (touch, pain, temperature)
Auditory
impulses
Descending
motor projections
to spinal cord
(b)
© 2012 Pearson Education, Inc.
Figure 7.16b
IV. Cerebellum
•Two hemispheres with convoluted surfaces
•Provides involuntary
body movements
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of
Cerebral hemisphere
Corpus callosum
Choroid plexus of third
ventricle
Occipital lobe of
cerebral hemisphere
Thalamus
(encloses third ventricle)
Pineal gland
(part of epithalamus)
Corpora
quadrigemina
Midbrain
Cerebral
aqueduct
Third ventricle
Anterior
commissure
Hypothalamus
Optic chiasma
Pituitary gland
Mammillary body
Pons
Medulla oblongata
Spinal cord
Cerebral peduncle
of midbrain
Fourth ventricle
Choroid plexus
Cerebellum
(a)
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Figure 7.16a
Protection of the Central Nervous System
•Scalp and skin
•Skull and vertebral column
•Meninges
•Cerebrospinal fluid (CSF)
•Blood-brain barrier
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Skin of scalp
Periosteum
Bone of skull
Superior
sagittal sinus
Subdural
space
Subarachnoid
space
Periosteal
Meningeal
Dura
mater
Arachnoid mater
Pia mater
Arachnoid villus
Blood
vessel
Falx cerebri
(in longitudinal
fissure only)
(a)
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Figure 7.17a
Meninges
•
• Tough outermost layer
• Double-layered external covering
•
• Middle layer
•
• Internal layer
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Occipital lobe
Tentorium
cerebelli
Cerebellum
Arachnoid mater
over medulla
oblongata
(b)
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Skull
Scalp
Superior
sagittal sinus
Dura mater
Transverse
sinus
Temporal
bone
Figure 7.17b
Cerebrospinal Fluid (CSF)
•Similar to blood plasma composition
•Formed by the choroid plexus
•Choroid plexuses–capillaries in the
ventricles of the brain
•Forms a watery
the brain
•Circulated in arachnoid space, ventricles, and
central canal of the spinal cord
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Cerebrospinal Fluid (CSF) Pathway of Flow
1. CSF is produced by the
each ventricle.
of
2. CSF flows through the ventricles and into the
subarachnoid space via the median and lateral
apertures. Some CSF flows through the central canal of
the spinal cord.
3. CSF flows through the subarachnoid space.
4. CSF is absorbed into the dural venous sinuses via the
arachnoid villi.
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Lateral ventricle
Anterior horn
Septum
pellucidum
Interventricular
foramen
Inferior
horn
Third ventricle
Lateral
aperture
Cerebral aqueduct
Fourth ventricle
Central canal
(a) Anterior view
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Figure 7.18a
Lateral ventricle
Anterior horn
Posterior
horn
Interventricular
foramen
Third ventricle
Inferior horn
Cerebral aqueduct
Median
aperture
Fourth ventricle
Lateral
aperture
Central canal
(b) Left lateral view
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Figure 7.18b
4
Superior
sagittal sinus
Arachnoid villus
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater
Right lateral ventricle
(deep to cut)
Choroid plexus
Corpus
callosum
1
Interventricular
foramen
Third ventricle
3
Cerebral aqueduct
Lateral aperture
Fourth ventricle
Median aperture
Central canal
of spinal cord
(c) CSF circulation
Choroid plexus
of fourth ventricle
2
1 CSF is produced by the
choroid plexus of each ventricle.
2 CSF flows through the ventricles
and into the subarachnoid space via
the median and lateral apertures.
Some CSF flows through the central
canal of the spinal cord.
3 CSF flows through the
subarachnoid space.
4 CSF is absorbed into the dural
venous sinuses via the arachnoid
villi.
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Figure 7.18c
Blood-Brain Barrier
•Includes the least permeable capillaries of the
body
•Excludes many potentially harmful substances
•Useless as a barrier against:
• Fats and fat soluble molecules
• Respiratory gases
• Alcohol
• Nicotine
• Anesthesia
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Traumatic Brain Injuries
•
• Slight brain injury
• No permanent brain damage
•
• Nervous tissue destruction occurs
• Nervous tissue does not regenerate
•
• Swelling from the inflammatory response
• May compress and kill brain tissue
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Cerebrovascular Accident (CVA) or
• Result from a ruptured blood vessel supplying a region of
the brain
• Brain tissue supplied with oxygen from that blood
source dies
• Loss of some functions or death may result
• Hemiplegia – One-sided paralysis
• Aphasis – Damage to speech center in left hemisphere
•
-attack (TIA) –
temporary brain ischemia (restriction of blood flow)
• Warning signs for more serious CVAs
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Disease
• Progressive degenerative brain disease
• Mostly seen in the elderly, but may begin in
middle age
• Structural changes in the brain include abnormal
protein deposits and twisted fibers within neurons
• Victims experience memory loss, irritability,
confusion, and ultimately, hallucinations and
death
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Spinal Cord
•Extends from the foramen magnum of the
skull to the first or second lumbar vertebra
•Provides a two-way conduction pathway from
the brain to and from the brain
•
pairs of spinal nerves arise from the
spinal cord
•
is a collection
of spinal nerves at the inferior end
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Cervical
spinal nerves
Cervical
enlargement
C8
Dura and
arachnoid
mater
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Thoracic
spinal nerves
Figure 7.20 (1 of 2)
Lumbar
enlargement
T12
Cauda
equina
End of
meningeal
coverings
End of
spinal cord
Lumbar
spinal nerves
L5
S1
Sacral
spinal nerves
S5
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Figure 7.20 (2 of 2)
Spinal Cord Anatomy
•
matter is mostly cell bodies
• Dorsal (posterior) horns
• Anterior (ventral) horns
• Gray matter surrounds the central canal
• Central canal is filled with cerebrospinal fluid
matter — conduction tracts
•
• Dorsal, lateral, ventral columns
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Dorsal root
ganglion
White matter
Central canal
Dorsal (posterior)
horn of gray matter
Lateral horn of
gray matter
Spinal nerve
Dorsal root of
spinal nerve
Ventral root
of spinal nerve
Ventral (anterior)
horn of gray matter
Pia mater
Arachnoid mater
Dura mater
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Figure 7.21
Spinal Cord Anatomy
• Meninges cover the spinal cord
• Spinal nerves leave at the level of each vertebrae
•
root
• Associated with the dorsal root ganglia—
collections of cell bodies outside the central
nervous system
•
root
• Contains axons
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Interneuron carrying sensory
information to cerebral cortex
Integration (processing
and interpretation of
sensory input) occurs
Cerebral cortex
(gray matter)
White matter
Interneuron carrying
response to
motor neurons
Thalamus
Cerebrum
Interneuron
carrying response
to motor neuron
Brain stem
Cell body of sensory
neuron in sensory
ganglion
Interneuron carrying
sensory information to
cerebral cortex
Nerve
Skin
Sensory
receptors
Cervical spinal cord
Muscle
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Motor output
Motor neuron
cell body
White matter
Gray matter
Interneuron
Figure 7.22