powerpoint lecture

Report
Anatomy & Physiology I
Lecture 11
Chapter 12: The Central Nervous
System
The Central Nervous System
• The Brain and Spinal Cord
• Brain has four adult regions:
– Cerebral hemispheres
– Diencephalon
– Brain stem (midbrain, pons, and medulla)
– Cerebellum
Figure 12.2c Brain development.
Cerebral
hemisphere
Diencephalon
Cerebellum
Brain stem
• Midbrain
• Pons
• Medulla oblongata
Birth: Shows adult pattern of structures and convolutions.
© 2013 Pearson Education, Inc.
Ventricles of the Brain
• Filled with cerebrospinal fluid (CSF)
– Lined by ependymal cells
– Continuous with one another
• Paired Lateral ventricles
– cerebral hemisphere
• Third ventricle
– diencephalon
• Fourth ventricle
– hindbrain
Communication Among Ventricles
• Lateral ventricles communicates to third
ventricle via interventricular foramen
• Third ventricle communicates to fourth
ventricle via cerebral aqueduct
• Fourth ventricle is continuous with the central
canal of the spinal cord
Figure 12.3 Ventricles of the brain.
Lateral
ventricle
Anterior
horn
Interventricular
foramen
Septum
pellucidum
Inferior
horn
Posterior
horn
Third
ventricle
Inferior
horn
Median
aperture
Cerebral aqueduct
Lateral
aperture
Fourth ventricle
Lateral
aperture
Central canal
Anterior view
© 2013 Pearson Education, Inc.
Left lateral view
Cerebral Hemisphere
• Forms the Superior part of the brain
• Surface markings
– Ridges (gyri), shallow grooves (sulci), and deep
grooves (fissures)
• Longitudinal fissure
– Separates two hemispheres
• Transverse cerebral fissure
– Separates cerebrum and cerebellum
The Lobes
• Five lobes
– Frontal
– Parietal
– Temporal
– Occipital
– Insula
• Each lobe is separated by several sulci
Major Sulci
• 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
Figure 12.4c Lobes, sulci, and fissures of the cerebral hemispheres.
Precentral
gyrus
Frontal lobe
Central
sulcus
Postcentral
gyrus
Parietal lobe
Parieto-occipital sulcus
(on medial surface
of hemisphere)
Lateral sulcus
Fissure
(a deep
sulcus)
Occipital lobe
Temporal lobe
Transverse
cerebral fissure
Cerebellum
Pons
Medulla oblongata
Spinal cord
Gyrus
Cortex (gray matter)
Sulcus
White matter
Lobes and sulci of the cerebrum
© 2013 Pearson Education, Inc.
Figure 12.4d Lobes, sulci, and fissures of the cerebral hemispheres.
Frontal lobe
Central
sulcus
Gyri of insula
Temporal lobe
(pulled down)
Location of the insula lobe
© 2013 Pearson Education, Inc.
Central Hemisphere
• Three basic regions
– Cerebral cortex of gray matter superficially
– White matter internally
– Basal nuclei deep within white matter
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
Four Generalizations of Cerebral
Cortex
• Functional areas
– Motor areas—control voluntary movement
– Sensory areas—conscious awareness of sensation
– Association areas—integrate diverse information
• Each hemisphere concerned with contralateral
(opposite) side of body
Four Generalizations of Cerebral
Cortex
• Two hemispheres are not equal in function
– Lateral specialization of cortical function
• Conscious behavior involves entire cortex in
some way
Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal
eye field
Broca's area
(outlined by dashes)
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Wernicke's area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Lateral view, left cerebral hemisphere
Primary motor
cortex
Taste
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
Motor Areas
•
•
•
•
Primary Motor cortex
Premotor cortex
Frontal eyelid field
Broca’s area
Primary Motor Cortex
• Allows conscious control of precise, skilled,
skeletal muscle movements
Figure 12.7 Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Posterior
Motor
Sensory
Anterior
Hip
Trunk
Neck
Motor map in
precentral gyrus
Sensory map in
postcentral gyrus
Foot
Knee
Toes
Genitals
Jaw
Tongue
Swallowing
© 2013 Pearson Education, Inc.
Primary motor
cortex
(precentral gyrus)
Primary somatosensory cortex
(postcentral gyrus)
Intraabdominal
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
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
Frontal Eye Field
• Controls voluntary eye movements
Sensory Areas of Cerebral Cortex
• Conscious awareness of sensation
• Occur in parietal, insular, temporal, and
occipital lobes
Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal
eye field
Broca's area
(outlined by dashes)
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Wernicke's area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Lateral view, left cerebral hemisphere
Primary motor
cortex
Taste
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
Primary Somatosensory Cortex
• Receives general sensory information from
skin, and proprioceptors of skeletal muscle,
joints, and tendons
• Capable of spatial discrimination:
identification of body region being stimulated
Figure 12.7b Body maps in the primary motor cortex and somatosensory cortex of the cerebrum.
Posterior
Sensory
Neck
Hip
Trunk
Anterior
Sensory map in
postcentral gyrus
Foot
Genitals
Primary somatosensory cortex
(postcentral gyrus)
© 2013 Pearson Education, Inc.
Intraabdominal
Somatosensory Association Cortex
• Integrates sensory input from primary
somatosensory cortex for understanding of
object
• Determines size, texture, and relationship of
parts of objects being felt
Visual Areas
• Primary visual (striate) cortex
– Extreme posterior tip of occipital lobe
– Receives visual information from retinas
• Visual association area
– Surrounds primary visual cortex
– Uses past visual experiences to interpret visual
stimuli (e.g., color, form, and movement)
• ability to recognize faces
Audio Areas
• Primary auditory cortex
– Superior margin of temporal lobes
– Interprets information from inner ear as pitch,
loudness, and location
• Auditory association area
– Located posterior to primary auditory cortex
– Stores memories of sounds and permits
perception of sound stimulus
Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal
eye field
Broca's area
(outlined by dashes)
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Wernicke's area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Lateral view, left cerebral hemisphere
Primary motor
cortex
Taste
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
Olfactory cortex
• Primary olfactory (smell) cortex
• Medial aspect of temporal
• Region of conscious awareness of odors
Gustatory cortex
• In insula just deep to temporal lobe
• Involved in perception of taste
Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal
eye field
Broca's area
(outlined by dashes)
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Wernicke's area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Lateral view, left cerebral hemisphere
Primary motor
cortex
Taste
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
Figure 12.6b Functional and structural areas of the cerebral cortex.
Premotor
cortex
Cingulate Primary
gyrus
motor cortex
Corpus
callosum
Central sulcus
Primary somatosensory
cortex
Frontal eye field
Parietal lobe
Somatosensory
association cortex
Parieto-occipital
sulcus
Prefrontal
cortex
Occipital
lobe
Processes emotions
related to personal
and social interactions
Visual association
area
Orbitofrontal
cortex
Olfactory bulb
Olfactory tract
Fornix
Temporal
lobe
Primary
olfactory
cortex
Parasagittal view, right cerebral hemisphere
Primary motor
cortex
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Uncus
Calcarine
sulcus
Parahippocampal
gyrus
Sensory
association cortex
Primary
visual cortex
Multimodal association
cortex
Multimodal Association Areas
• Most of cortex works together via complex connections
– Receive inputs from multiple sensory areas
– Send outputs to multiple areas, including premotor cortex
• Allows meaning to information received, store in
memory, tying to previous experience, and deciding on
actions
• Sensations, thoughts, emotions become conscious –
makes us who we are
Multimodal Association Areas
• Three broad parts:
– Anterior association area (prefrontal cortex)
– Posterior association area
– Limbic association area
Anterior Association Area (Prefrontal
Cortex)
• Most complicated cortical region
– Involved with intellect, cognition, recall, and
personality
• Contains working memory needed for abstract
ideas, judgment, reasoning, persistence, and
planning
– Development depends on feedback from social
environment
Figure 12.6a Functional and structural areas of the cerebral cortex.
Motor areas
Central sulcus
Primary motor cortex
Premotor cortex
Frontal
eye field
Broca's area
(outlined by dashes)
Sensory areas and related
association areas
Primary somatosensory
cortex
Somatic
Somatosensory
sensation
association cortex
Gustatory cortex
(in insula)
Prefrontal cortex
Working memory
for spatial tasks
Executive area for
task management
Working memory for
object-recall tasks
Solving complex,
multitask problems
Wernicke's area
(outlined by dashes)
Primary visual
cortex
Visual
association
area
Auditory
association area
Primary
auditory cortex
Lateral view, left cerebral hemisphere
Primary motor
cortex
Taste
Motor association
cortex
© 2013 Pearson Education, Inc.
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
Posterior Association Area
• Large region in temporal, parietal, and
occipital lobes
• Plays role in recognizing patterns and faces
and localizing us in space
• Involved in understanding written and spoken
language (Wernicke's area)
Limbic Association Area
• Part of limbic system
• Provides emotional impact that makes scene
important and helps establish memories
Lateralization of Cortical Function
• Lateralization of hemisperes
– division of labor between hemispheres
• Left hemisphere
– Controls language, math, and logic
• Right hemisphere
– Visual-spatial skills, intuition, emotion, and artistic
and musical skills
Cerebral White Matter
• Myelinated fibers and tracts
• Communication between cerebral areas, and
between cortex and lower CNS
Cerebral White Matter
• Association fibers
– horizontal; connect different parts of same
hemisphere
• Commissural fibers
– horizontal; connect gray matter of two
hemispheres
• Projection fibers
– vertical; connect hemispheres with lower brain or
spinal cord
Figure 12.8a White fiber tracts of the cerebral hemispheres.
Longitudinal fissure
Superior
Lateral
ventricle
Basal nuclei
• Caudate
• Putamen
• Globus
pallidus
Thalamus
Third
ventricle
Association fibers
(within hemisphere)
Commissural fibers
(between hemispheres)
• Corpus callosum
Projection fibers
(cerebral cortex
to lower area)
• Corona
radiata
• Internal
capsule
Gray matter
White matter
Pons
Medulla oblongata
Frontal section
© 2013 Pearson Education, Inc.
Decussation
(cross-over)
of pyramids
Figure 12.8b White fiber tracts of the cerebral hemispheres.
Association fibers
Commissural fibers
• Corpus callosum
Projection fibers
• Corona radiata
• Internal capsule
Parasagittal section and dissection
© 2013 Pearson Education, Inc.
Gray
matter
Basal Nuclei
• Precise structure is controversial
• Precise role elusive
– Influence muscle movement
– Role in cognition and emotion
– Filter out incorrect or inappropriate responses
(movements)
Diencephalon
• Three paired structures
– Thalamus
– Hypothalamus
– Epithalamus
Figure 12.10a Midsagittal section of the brain.
Cerebral hemisphere
Corpus callosum
Fornix
Choroid plexus
Septum pellucidum
Interthalamic
adhesion
(intermediate
mass of thalamus)
Thalamus
(encloses third ventricle)
Posterior
commissure
Pineal gland
Interventricular
foramen
Anterior
commissure
Hypothalamus
Optic chiasma
Epithalamus
Corpora
quadrigemina Midbrain
Cerebral
aqueduct
Pituitary gland
Mammillary
body
Pons
Medulla
oblongata
Spinal cord
© 2013 Pearson Education, Inc.
Arbor vitae (of cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Thalamus
• Gateway to cerebral cortex
• Sorts, edits, and relays ascending input
– Impulses from hypothalamus for regulation of
emotion and visceral function
– Impulses from cerebellum and basal nuclei to help
direct motor cortices
– Impulses for memory or sensory integration
• Mediates sensation, motor activities, cortical
arousal, learning, and memory
Hypothalamus
• Controls autonomic nervous system
– blood pressure, rate and force of heartbeat,
digestive tract motility, pupil size
• Physical responses to emotions (limbic
system)
– Perception of pleasure, fear, and rage, and in
biological rhythms and drives
Hypothalamus (Ch 16)
• Regulates body temperature
– sweating/shivering
• Regulates hunger and satiety in response to
nutrient blood levels or hormones
• Regulates water balance and thirst
• Regulates sleep-wake cycles
– biological clock
• Controls endocrine system
– Controls secretions of anterior pituitary gland
– Produces posterior pituitary hormones
Epithalamus
• Pineal gland (body)—extends from posterior
border and secretes melatonin
– Melatonin—helps regulate sleep-wake cycle
The Brain Stem
• Three regions
– Midbrain
– Pons
– Medulla oblongata
Brain Stem
• Similar structure to spinal cord
• Controls automatic behaviors necessary for
survival
• Nuclei associated with 10 of the 12 pairs of
cranial nerves
Figure 12.10b Midsagittal section of the brain.
Corpus callosum
Fornix
Thalamus
Lateral ventricle
(covered by septum
pellucidum)
Posterior
commissure
Pineal gland
Third ventricle
Epithalamus
Corpora
quadrigemina
Cerebral
aqueduct
Anterior
commissure
Hypothalamus
Arbor vitae
Fourth ventricle
Optic chiasma
Cerebellum
Mammillary body
Pons
Medulla oblongata
© 2013 Pearson Education, Inc.
Midbrain
Pons
• Connect higher brain centers and spinal cord
• Relay impulses between motor cortex and
cerebellum
Medulla Oblongata
• Autonomic reflex center
– Functions overlap with hypothalamus
– Hypothalamus relays instructions via medulla
• Cardiovascular center (Ch 19)
– Cardiac center adjusts force and rate of heart
contraction
– Vasomotor center adjusts blood vessel diameter
for blood pressure regulation
Medulla Oblongata
• Respiratory centers (Ch. 22)
– Generate respiratory rhythm
– Control rate and depth of breathing (with pontine
centers)
• Additional centers regulate
–
–
–
–
–
Vomiting
Hiccuping
Swallowing
Coughing
Sneezing
Cerebellum
• Input from cortex, brain stem and sensory
receptors
• Allows smooth, coordinated movements
Cerebellar Processing of Motor Activity
• Cerebellum receives impulses from cerebral
cortex of intent to initiate voluntary muscle
contraction
• Inform body's position and momentum
– calculates the best way to smoothly coordinate
muscle contraction
Cognitive Function of Cerebellum
• Role in thinking, language, and emotion
Functional Brain Systems
• Networks of neurons that work together but
span wide areas of brain
– Limbic system
– Reticular formation
Limbic System
• Emotional or affective brain
– recognizes angry or fearful facial expressions,
assesses danger, and elicits fear response
– role in expressing emotions via gestures, and
resolves mental conflict
– Puts emotional responses to odors
Reticular Formation
• Sends impulses to cerebral cortex to keep it
conscious and alert
• Reticular autonomic centers regulate visceral
motor functions
– Vasomotor centers
– Cardiac center
– Respiratory centers
Protection of the Brain
• Meninges
• Consists of three connective tissue
membranes that:
– Cover and protect CNS
– Protect blood vessels and enclose venous system
– Contain cerbrospinal fluid
– Form partitions in the skull
Cerebrospinal Fluid (CSF)
• Watery solution formed from blood plasma
• Produced by the choroid plexus of each ventricle
• Gives buoyancy to CNS structures
• Reduces weight by 97%
• Protects CNS from blows and other trauma
• Nourishes brain and carries chemical signals
Figure 12.24a Formation, location, and circulation of CSF.
Superior
sagittal sinus
Slide 1
Arachnoid villus
Choroid plexus
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater
1
Interventricular
foramen
Third ventricle
Cerebral aqueduct
Lateral aperture
Fourth ventricle
Median aperture
Central canal
of spinal cord
(a) CSF circulation
© 2013 Pearson Education, Inc.
Right lateral ventricle
(deep to cut)
Choroid plexus
of fourth ventricle
Blood Brain Barrier
• Helps maintain stable environment for brain
• Separates neurons from some bloodborne
substances
• Astrocytes support function
• Selective barrier
– Allows nutrients to move by diffusion
– Metabolic wastes, proteins, toxins, most drugs, small
nonessential amino acids, K+ denied
– Allows any fat-soluble substances to pass, including
alcohol, nicotine, and anesthetics
The Spinal Cord
• Travels via the vertebral column via vertebral
foramen
– Protected by bone, meninges, and CSF
• Function
– Provides two-way communication to and from
brain
Figure 12.26a Gross structure of the spinal cord, dorsal view.
Cervical
enlargement
Dura and
arachnoid
mater
Lumbar
enlargement
Conus
medullaris
Cauda
equina
Filum
terminale
Cervical
spinal
nerves
Thoracic
spinal nerves
Lumbar
spinal nerves
Sacral
spinal nerves
The spinal cord and its nerve roots, with the bony
vertebral
arches removed. The dura mater and
© 2013 Pearson Education,
Inc.
arachnoid mater are cut open and reflected laterally.
The Spinal cord
• Terminates in conus medullaris (~L1)
• Filum terminale extends to coccyx
– Fibrous nerve extension that continue down the
legs
– Anchors spinal cord
• Spinal nerves (Part of PNS)
– 31 pairs
Figure 12.28a Anatomy of the spinal cord.
Epidural space
(contains fat)
Subdural space
Subarachnoid
space
(contains CSF)
Pia mater
Arachnoid mater
Dura mater
Spinal meninges
Bone of
vertebra
Dorsal root
ganglion
Body
of vertebra
Cross section of spinal cord and vertebra
© 2013 Pearson Education, Inc.
Figure 12.28b Anatomy of the spinal cord.
Dorsal funiculus
White
columns
Ventral funiculus
Lateral funiculus
Dorsal median sulcus
Gray commissure
Dorsal horn
Gray
Ventral horn
matter
Lateral horn
Dorsal root
ganglion
Spinal nerve
Dorsal root
(fans out into
dorsal rootlets)
Central canal
Ventral median fissure
Pia mater
Ventral root
(derived from several
ventral rootlets)
Arachnoid mater
Spinal dura mater
The spinal cord and its meningeal coverings
© 2013 Pearson Education, Inc.
Nerves Serving Gray Matter
• Named by relative involvement in innervating
somatic and visceral regions of body
– Somatic sensory (SS)
– Visceral sensory (VS)
– Visceral (autonomic) motor (VM)
– Somatic motor (SM)
Figure 12.29 Organization of the gray matter of the spinal cord.
Dorsal root
(sensory)
Dorsal horn (interneurons)
Dorsal root
ganglion
SS
VS
Somatic sensory neuron
VM
Visceral sensory
neuron
SM
Visceral motor
neuron
Somatic motor neuron
Spinal nerve
Ventral horn
(motor neurons)
Ventral root
(motor)
© 2013 Pearson Education, Inc.
SS
Interneurons receiving input from somatic sensory neurons
VS
Interneurons receiving input from visceral sensory neurons
VM
Visceral motor (autonomic) neurons
SM
Somatic motor neurons
White Matter
• Nerve fibers allow communication between
parts of spinal cord, and spinal cord and brain
• Run in three directions
– Ascending – up to higher centers (sensory inputs)
– Descending – from brain to cord or lower cord
levels (motor outputs)
– Transverse – from one side to other (commissural
fibers)
Figure 12.30 Major ascending (sensory) and descending (motor) tracts of the spinal cord, cross-sectional view.
Ascending tracts
Dorsal Fasciculus gracilis
white Fasciculus cuneatus
column
Dorsal
spinocerebellar tract
Ventral
spinocerebellar
tract
Lateral spinothalamic
tract
Ventral spinothalamic
tract
Descending tracts
Ventral white
commissure
Lateral
reticulospinal tract
Lateral
corticospinal
tract
Rubrospinal tract
Medial
reticulospinal tract
Ventral
corticospinal tract
Vestibulospinal tract
Tectospinal tract
© 2013 Pearson Education, Inc.
Summary of Spinal Cord Nerves
• White matter
– contain nerves that move up and down the
column to relay signals to brain the organ systems
• Gray matter
– contain nerves that move outward to the PNS for
sensory and motor function
Lab Exercise
• Lab Exercise 19
– Parts of the Brain
– Cranial Nerves (Wednesday’s lecture)

similar documents