© 2013 pearson education, inc. central nervous system (cns) cns consists of brain and spinal cord...
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© 2013 Pearson Education, Inc.
Central Nervous System (CNS)
• CNS consists of brain and spinal cord
• Cephalization– Evolutionary development of rostral (anterior)
portion of CNS– Increased number of neurons in head– Highest level reached in human brain
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Regions and Organization
• Adult brain regions1. Cerebral hemispheres
2. Diencephalon
3. Brain stem (midbrain, pons, and medulla)
4. Cerebellum
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Figure 12.2c Brain development.
Cerebralhemisphere
Diencephalon
Cerebellum
Brain stem• Midbrain• Pons• Medulla oblongata
Birth: Shows adult pattern of structures and convolutions.
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Regions and Organization of the CNS
• Spinal cord – Central cavity surrounded by gray matter – External white matter composed of myelinated
fiber tracts
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Regions and Organization of the CNS
• Brain– Similar pattern– Additional areas of gray matter in brain– Cerebral hemispheres and cerebellum
• Outer gray matter called cortex
– Cortex disappears in brain stem• Scattered gray matter nuclei amid white matter
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Ventricles of the Brain
• Filled with cerebrospinal fluid (CSF)
• Connected to one another and to central canal of spinal cord– Lateral ventricles third ventricle via
interventricular foramen– Third ventricle fourth ventricle via cerebral
aqueduct
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Ventricles of the Brain
• Paired, C-shaped lateral ventricles in cerebral hemispheres– Separated anteriorly by septum pellucidum
• Third ventricle in diencephalon
• Fourth ventricle in hindbrain– Three openings: paired lateral apertures in
side walls; median aperture in roof• Connect ventricles to subarachnoid space
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Figure 12.3 Ventricles of the brain.
Septumpellucidum
Inferiorhorn
Lateralaperture
Lateralventricle
Anteriorhorn
Interventricularforamen
Thirdventricle
Cerebral aqueduct
Fourth ventricle
Central canal
Posteriorhorn
InferiorhornMedianaperture
Lateralaperture
Anterior view Left lateral view
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Cerebral Hemispheres
• Surface markings– Ridges (gyri), shallow grooves (sulci), and
deep grooves (fissures)– Longitudinal fissure
• Separates two hemispheres
– Transverse cerebral fissure• Separates cerebrum and cerebellum
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PLAYPLAY Animation: Rotatable brain
Cerebral Hemispheres
• Five lobes– Frontal– Parietal – Temporal – Occipital– Insula
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Cerebral Hemispheres
• Central sulcus– Separates precentral gyrus of frontal lobe
and postcentral gyrus of parietal lobe
• Parieto-occipital sulcus– Separates occipital and parietal lobes
• Lateral sulcus outlines temporal lobes
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Cerebral Hemispheres
• Three basic regions– Cerebral cortex of gray matter superficially– White matter internally– Basal nuclei deep within white matter
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Figure 12.4c Lobes, sulci, and fissures of the cerebral hemispheres.
Frontal lobe
Postcentralgyrus
Parietal lobe
CentralsulcusPrecentral
gyrus
Parieto-occipital sulcus(on medial surfaceof hemisphere)
Lateral sulcus
Temporal lobeOccipital lobe
Transversecerebral fissure
Pons
Spinal cordFissure(a deepsulcus)
Gyrus
Cortex (gray matter)
Sulcus
White matter
Lobes and sulci of the cerebrum
Medulla oblongata
Cerebellum
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Frontal lobeCentralsulcus
Gyri of insula
Temporal lobe(pulled down)
Location of the insula lobe
Figure 12.4d Lobes, sulci, and fissures of the cerebral hemispheres.
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Figure 12.4a Lobes, sulci, and fissures of the cerebral hemispheres.
Anterior
Longitudinalfissure
Frontal lobe
Cerebral veinsand arteriescovered byarachnoidmater
Left cerebralhemisphere
Parietal lobe
Right cerebralhemisphere
Occipitallobe
Superior view
Posterior
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Figure 12.4b Lobes, sulci, and fissures of the cerebral hemispheres.
Left cerebralhemisphere
Transversecerebralfissure
Cerebellum
Brain stem
Left lateral view
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Cerebral Cortex
• Thin (2–4 mm) superficial layer of gray matter
• 40% mass of brain
• Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding
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4 General Considerations of Cerebral Cortex
1. Three types of functional areas– Motor areas—control voluntary movement– Sensory areas—conscious awareness of
sensation– Association areas—integrate diverse
information
2. Each hemisphere concerned with contralateral side of body
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4 General Considerations of Cerebral Cortex
3. Lateralization of cortical function in hemispheres
4. Conscious behavior involves entire cortex in some way
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Motor Areas of Cerebral Cortex
• In frontal lobe; control voluntary movement
• Primary (somatic) motor cortex in precentral gyrus
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Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Primary motor cortex
Premotor cortexFrontaleye fieldBroca's area(outlined by dashes)
Working memoryfor spatial tasks
Executive area fortask management
Working memory for object-recall tasksSolving complex,multitask problems
Prefrontal cortex
Lateral view, left cerebral hemisphere
Sensory areas and relatedassociation areasPrimary somatosensorycortexSomatosensoryassociation cortex
Gustatory cortex(in insula)
Somatic sensation
Taste
Wernicke's area(outlined by dashes)
Primary visualcortexVisualassociation area
Auditoryassociation area
Primary auditory cortex
Vision
Hearing
Central sulcus
Primary motorcortex
Motor associationcortex
Primary sensorycortex
Sensoryassociation cortex
Multimodal associationcortex
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Primary Motor Cortex
• Large pyramidal cells of precentral gyri
• Long axons pyramidal (corticospinal) tracts of spinal cord
• Allows conscious control of precise, skilled, skeletal muscle movements
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Figure 12.7 Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Posterior
Motor SensoryAnterior
Primary motorcortex(precentral gyrus)
Primary somato-sensory cortex(postcentral gyrus)
Motor map inprecentral gyrus
Sensory map inpostcentral gyrus
Swallowing
Tongue
Jaw
Lips
Face
Eye
Brow
Neck
Thumb
Fingers
Hand
Elb
ow
Wrist
Toes
Genitals
Arm
Sh
ou
lder
Tru
nk
Hip
Fo
ot
Kn
ee
Kn
ee
Leg Hip
Tru
nk
Ne
ck
Hea
dA
rmE
lbow
Fore
arm
Han
d
Fing
ers
Thum
b
Eye
Nose
Face
Lips
Teeth
JawGums
Tongue
Pharynx
Intra-abdominal
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Premotor Cortex
• Helps plan movements; staging area for skilled motor activities
• Controls learned, repetitious, or patterned motor skills
• Coordinates simultaneous or sequential actions
• Controls voluntary actions that depend on sensory feedback
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Broca's Area
• Present in one hemisphere (usually the left)
• Motor speech area that directs muscles of speech production
• Active in planning speech and voluntary motor activities
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Frontal Eye Field
• Controls voluntary eye movements
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Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Primary motor cortex
Premotor cortexFrontaleye fieldBroca's area(outlined by dashes)
Working memoryfor spatial tasks
Executive area fortask management
Working memory for object-recall tasksSolving complex,multitask problems
Prefrontal cortex
Lateral view, left cerebral hemisphere
Sensory areas and relatedassociation areasPrimary somatosensorycortexSomatosensoryassociation cortex
Gustatory cortex(in insula)
Somatic sensation
Taste
Wernicke's area(outlined by dashes)
Primary visualcortexVisualassociation area
Auditoryassociation area
Primary auditory cortex
Vision
Hearing
Central sulcus
Primary motorcortex
Motor associationcortex
Primary sensorycortex
Sensoryassociation cortex
Multimodal associationcortex
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Figure 12.6b Functional and structural areas of the cerebral cortex.
Corpuscallosum
Frontal eye field
Prefrontalcortex
Processes emotionsrelated to personaland social interactions
Orbitofrontalcortex
Olfactory bulb
Olfactory tract
FornixTemporallobe
Primaryolfactorycortex
Uncus
Calcarine sulcus
Parahippocampalgyrus
Parietal lobe
Somatosensoryassociation cortex
Parieto-occipitalsulcus
Occipitallobe
Visual associationarea
Primaryvisual cortex
Primary somatosensorycortex
Central sulcusPrimarymotor cortex
Cingulategyrus
Premotorcortex
Parasagittal view, right cerebral hemisphere
Primary motorcortex
Motor associationcortex
Primary sensorycortex
Sensoryassociation cortex
Multimodal associationcortex
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• Vestibular cortex
• Olfactory cortex
• Gustatory cortex
• Visceral sensory area
Sensory Areas of Cerebral Cortex
• Primary somatosensory cortex
• Somatosensory association cortex
• Visual areas
• Auditory areas
• Conscious awareness of sensation• Occur in parietal, insular, temporal, and
occipital lobes
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Figure 12.7b Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Posterior
SensoryAnterior
Primary somato-sensory cortex(postcentral gyrus)
Sensory map inpostcentral gyrus
Genitals
Fo
ot
Kn
ee
Leg Hip
Tru
nk
Ne
ck
Hea
dA
rmE
lbow
Fore
arm
Han
d
Fing
ers
Thum
b
Eye
Nose
Face
Lips
Teeth
JawGums
Tongue
Pharynx
Intra-abdominal