Chapter 12 - The central nervous system (part a), the topics discussed in this chapter are: Central Nervous System (CNS), embryonic development, effect of space restriction on brain development, regions and organization of the CNS, ventricles of the brain,...and other contents.
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prepared by Janice Meeking, Mount Royal College
C H A P T E R
Copyright © 2010 Pearson Education, Inc.
12
The Central Nervous
System:
Part A
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Central Nervous System (CNS)
• Evolutionary development of the rostral
(anterior) portion of the CNS
• Increased number of neurons in the head
• Highest level is reached in the human brain
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Embryonic Development
groove and neural folds
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The neural plate forms from surface ectoderm.
1
Head
Tail
Surface ectoderm
Neural plate
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The neural plate invaginates, forming the neural
groove, flanked by neural folds.
2
Neural folds
Neural groove
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Neural fold cells migrate to form the neural crest,
which will form much of the PNS and many other
structures.
3
Neural crest
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The neural groove becomes the neural tube, which
will form CNS structures.
4
Surface ectoderm Head
Tail
Neural
tube
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Embryonic Development
three primary brain vesicles
• Prosencephalon—forebrain
• Mesencephalon—midbrain
• Rhombencephalon—hindbrain
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(a) Neural tube
(b) Primary brain vesicles
Anterior (rostral)
Posterior (caudal)
Rhombencephalon (hindbrain)
Mesencephalon (midbrain)
Prosencephalon (forebrain)
Figure 12.2a-b
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• Mesencephalon remains undivided
• Metencephalon and myelencephalon arise from the hindbrain
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Embryonic Development
with cortex, white matter, and basal nuclei)
epithalamus, and retina
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Embryonic Development
cerebellum
oblongata)
form fluid-filled ventricles
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(d) Adult brain structures
(c) Secondary brain
vesicles
Spinal cord
Cerebellum Brain stem: medulla oblongata
Brain stem: pons Brain stem: midbrain
Diencephalon (thalamus, hypothalamus, epithalamus), retina
Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei)
Myelencephalon Metencephalon Mesencephalon Diencephalon Telencephalon
Central canal
Fourth ventricle
Cerebral aqueduct Third ventricle
Lateral ventricles
(e) Adult neural canal regions
Figure 12.2c-e
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Effect of Space Restriction on Brain
Development
forebrain to move toward the brain stem
laterally
fold into convolutions
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Flexures
Telencephalon
Myelencephalon
(a) Week 5
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Midbrain Cerebellum Pons
Medulla oblongata Spinal cord
Cerebral hemisphere Outline of diencephalon
(b) Week 13
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Cerebellum Pons
Medulla oblongata Spinal cord
Cerebral hemisphere
(c) Week 26
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Regions and Organization of the CNS
1 Cerebral hemispheres
2 Diencephalon
3 Brain stem (midbrain, pons, and medulla)
4 Cerebellum
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Cerebellum Diencephalon
Cerebral hemisphere
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Regions and Organization of the CNS
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Regions and Organization of the CNS
• Brain
• Similar pattern with additional areas of gray matter
• Nuclei in cerebellum and cerebrum
• Cortex of cerebellum and cerebrum
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Cerebrum
Cerebellum
Migratory pattern of neurons
Cortex of gray matter Inner gray matter
Gray matter
Outer white matter
Central cavity
Central cavity Inner gray matter
Gray matter Outer white matter
Central cavity Inner gray matter Outer white matter
Region of cerebellum
Brain stem
Spinal cord
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Ventricles of the Brain
canal of the spinal cord
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Ventricles of the Brain
• Two C-shaped lateral ventricles in the cerebral hemispheres
• Third ventricle in the diencephalon
• Fourth ventricle in the hindbrain, dorsal to the pons, develops from the lumen of the neural tube
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Anterior horn
Interventricular foramen
(a) Anterior view
Fourth ventricle
Central canal Inferior horn
Posterior horn
Median aperture Lateral aperture
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• Separates the two hemispheres
• Transverse cerebral fissure
• Separates the cerebrum and the cerebellum
PLAY Animation: Rotatable brain
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Postcentral gyrus
Central sulcus
Precentral gyrus
Frontal lobe
(a)
Parietal lobe
Parieto-occipital sulcus (on medial surface
of hemisphere) Lateral sulcus
Transverse cerebral fissure
Occipital lobe Temporal lobe
Cerebellum Pons
Medulla oblongata Spinal cord
Cortex (gray matter)
Fissure (a deep sulcus)
Gyrus Sulcus White matter
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Central sulcus
(b)
Frontal lobe
Temporal lobe (pulled down) Gyri of insula
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Parietal lobe Frontal lobe
Right cerebral hemisphere Occipital lobe
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Left cerebral hemisphere
Transverse cerebral
fissure
Cerebellum Brain stem
(d)
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Cerebral Cortex
• Thin (2–4 mm) superficial layer of gray matter
• 40% of the mass of the brain
• Site of conscious mind: awareness, sensory
perception, voluntary motor initiation, communication, memory storage, understanding
• Each hemisphere connects to contralateral side of
the body
• There is lateralization of cortical function in the
hemispheres
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Functional Areas of the Cerebral Cortex
• Motor areas—control voluntary movement
• Sensory areas—conscious awareness of
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Trang 36Copyright © 2010 Pearson Education, Inc. Figure 12.8a
Gustatory cortex (in insula)
Primary motor cortex
Premotor cortex
Frontal eye field
Working memory
for spatial tasks
Executive area for
Somatosensory association cortex
Somatic sensation Taste
Wernicke’s area (outlined by dashes)
Primary visual cortex
Visual association area
Vision
Auditory association area Primary
auditory cortex
Hearing
Primary motor cortex Motor association cortex Primary sensory cortex
Sensory association cortex Multimodal association cortex
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Primary Motor Cortex
voluntary movements
representing the motor innervation of body
regions
Trang 38Copyright © 2010 Pearson Education, Inc. Figure 12.9
Toes
Swallowing Tongue
Jaw
Primary motor cortex
(precentral gyrus)
Motor
Motor map in precentral gyrus
Posterior
Anterior
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Premotor Cortex
motor skills
actions
depend on sensory feedback
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Broca’s Area
• Anterior to the inferior region of the premotor area
the tongue
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Frontal Eye Field
to Broca’s area
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Trang 43Copyright © 2010 Pearson Education, Inc. Figure 12.8a
Gustatory cortex (in insula)
Primary motor cortex
Premotor cortex
Frontal eye field
Working memory
for spatial tasks
Executive area for
Somatosensory association cortex
Somatic sensation Taste
Wernicke’s area (outlined by dashes)
Primary visual cortex
Visual association area
Vision
Auditory association area Primary
auditory cortex
Hearing
Primary motor cortex Motor association cortex Primary sensory cortex
Sensory association cortex Multimodal association cortex
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Primary Somatosensory Cortex
• In the postcentral gyri
skeletal muscles, and joints
identification of body region being stimulated
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Genitals
abdominal
Intra-Primary sensory cortex
somato-(postcentral gyrus)
Sensory
Sensory map in postcentral gyrus
Posterior
Anterior
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Somatosensory Association Cortex
somatosensory cortex
parts of objects being felt
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Visual Areas
• Primary visual (striate) cortex
• Extreme posterior tip of the occipital lobe
• Most of it is buried in the calcarine sulcus
• Receives visual information from the retinas
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Visual Areas
• Surrounds the primary visual cortex
• Uses past visual experiences to interpret visual stimuli (e.g., color, form, and movement)
• Complex processing involves entire posterior half of the hemispheres
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Auditory Areas
• Superior margin of the temporal lobes
• Interprets information from inner ear as pitch, loudness, and location
• Located posterior to the primary auditory
cortex
• Stores memories of sounds and permits
perception of sounds
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OIfactory Cortex
lobes)
with the olfactory bulbs and tracts
• (Remainder of the rhinencephalon in humans
is part of the limbic system)
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Gustatory Cortex
• In the insula
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Visceral Sensory Area
e.g., upset stomach or full bladder
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Vestibular Cortex
parietal cortex
balance (position of the head in space)
Trang 54Copyright © 2010 Pearson Education, Inc. Figure 12.8a
Gustatory cortex (in insula)
Primary motor cortex
Premotor cortex
Frontal eye field
Working memory
for spatial tasks
Executive area for
Somatosensory association cortex
Somatic sensation Taste
Wernicke’s area (outlined by dashes)
Primary visual cortex
Visual association area
Vision
Auditory association area Primary
auditory cortex
Hearing
Primary motor cortex Motor association cortex Primary sensory cortex
Sensory association cortex Multimodal association cortex
Trang 55Copyright © 2010 Pearson Education, Inc. Figure 12.8b
Frontal eye field
Prefrontal
cortex
Processes emotions
related to personal
and social interactions
(b) Parasagittal view, right hemisphere
Olfactory bulb
Orbitofrontal
cortex
Olfactory tract Fornix
Temporal lobe
Corpus callosum
Premotor cortex Cingulate gyrus Primary motor cortex Central sulcus
Primary somatosensory cortex
Parietal lobe
Parieto-occipital sulcus
Somatosensory association cortex
Occipital lobe Visual association area
Calcarine sulcus Parahippocampal gyrus
Uncus Primary
olfactory cortex
Primary visual cortex
Primary motor cortex Motor association cortex Primary sensory cortex
Sensory association cortex Multimodal association cortex
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Multimodal Association Areas
premotor cortex
received, store it as memory, compare it to previous experience, and decide on action to take
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Multimodal Association Areas
• Anterior association area (prefrontal cortex)
• Posterior association area
• Limbic association area
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Anterior Association Area (Prefrontal
Cortex)
• Involved with intellect, cognition, recall, and personality
judgment, reasoning, persistence, and
conscience
social environment
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Posterior Association Area
occipital lobes
and localizing us in space
language (Wernicke’s area)
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Limbic Association Area
establish memories