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PowerPoint® Lecture Slides
prepared by
Barbara Heard,
Atlantic Cape Community
Ninth Edition
College
Human Anatomy & Physiology
CHAPTER
12
The Central
Nervous
System: Part A
© Annie Leibovitz/Contact Press Images
© 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
© 2013 Pearson Education, Inc.
Embryonic Development
• Brain and spinal cord begin as neural
tube
• 3 primary vesicles form at anterior end
– Prosencephalon or forebrain
– Mesencephalon or midbrain
– Rhombencephalon or hindbrain
• Posterior end becomes spinal cord
© 2013 Pearson Education, Inc.
Embryonic Development
• Primary vesicles  5 secondary brain
vesicles
– Forebrain  telencephalon and diencephalon
– Midbrain remains undivided
– Hindbrain  metencephalon and
myelencephalon
© 2013 Pearson Education, Inc.
Figure 12.1 Embryonic development of the human brain.
Neural tube
(contains
neural
canal)
Anterior
(rostral)
Primary brain vesicles
Secondary brain vesicles
Adult brain structures
Cerebrum: cerebral
hemispheres (cortex,
white matter, basal nuclei)
Lateral ventricles
Telencephalon
Prosencephalon
(forebrain)
Diencephalon
(thalamus, hypothalamus,
epithalamus), retina
Third ventricle
Diencephalon
Mesencephalon
(midbrain)
Mesencephalon
Brain stem: midbrain
Cerebral aqueduct
Metencephalon
Brain stem: pons
Rhombencephalon
(hindbrain)
Cerebellum
Myelencephalon
Posterior
(caudal)
© 2013 Pearson Education, Inc.
Adult neural
canal regions
Fourth ventricle
Brain stem: medulla
oblongata
Spinal cord
Central canal
Figure 12.2a Brain development.
Anterior (rostral)
Metencephalon
Mesencephalon
Diencephalon
Telencephalon
Myelencephalon
Posterior (caudal)
Midbrain
Cervical
Flexures
Spinal cord
Week 5: Two major flexures form, causing the
telencephalon and diencephalon to angle toward the brain stem.
© 2013 Pearson Education, Inc.
Figure 12.2b Brain development.
Cerebral hemisphere
Outline of diencephalon
Midbrain
Cerebellum
Pons
Medulla oblongata
Spinal cord
Week 13: Cerebral hemispheres develop and grow
posterolaterally to enclose the diencephalon and the
rostral brain stem.
© 2013 Pearson Education, Inc.
Regions and Organization
•
Adult brain regions
1.
2.
3.
4.
Cerebral hemispheres
Diencephalon
Brain stem (midbrain, pons, and medulla)
Cerebellum
© 2013 Pearson Education, Inc.
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.
Regions and Organization of the CNS
• Spinal cord
– Central cavity surrounded by gray matter
– External white matter composed of
myelinated fiber tracts
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Ventricles of the Brain
• Filled with cerebrospinal fluid (CSF)
• Lined by ependymal cells
• 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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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 Hemispheres
• Surface markings
– Ridges (gyri), shallow grooves (sulci), and
deep grooves (fissures)
– Longitudinal fissure
• Separates two hemispheres
– Transverse cerebral fissure
• Separates cerebrum and cerebellum
© 2013 Pearson Education, Inc.
Cerebral Hemispheres
• Five lobes
– Frontal
– Parietal
– Temporal
– Occipital
– Insula
PLAY
Animation: Rotatable brain
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Cerebral Hemispheres
• Three basic regions
– Cerebral cortex of gray matter superficially
– White matter internally
– Basal nuclei deep within white matter
© 2013 Pearson Education, Inc.
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.
Figure 12.4a Lobes, sulci, and fissures of the cerebral hemispheres.
Anterior
Longitudinal
fissure
Frontal lobe
Cerebral veins
and arteries
covered by
arachnoid
mater
Parietal lobe
Left cerebral
hemisphere
Right cerebral
hemisphere
Occipital
lobe
Posterior
Superior view
© 2013 Pearson Education, Inc.
Figure 12.4b Lobes, sulci, and fissures of the cerebral hemispheres.
Left cerebral
hemisphere
Brain stem
Transverse
cerebral
fissure
Cerebellum
Left lateral view
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
4 General Considerations of Cerebral Cortex
3. Lateralization of cortical function in
hemispheres
4. Conscious behavior involves entire cortex
in some way
© 2013 Pearson Education, Inc.
Figure 12.5 Functional neuroimaging (fMRI) of the cerebral cortex.
Longitudinal
fissure
© 2013 Pearson Education, Inc.
Left frontal
lobe
Left temporal
lobe
Central sulcus
Areas active
in speech and
hearing (fMRI)
Motor Areas of Cerebral Cortex
• In frontal lobe; control voluntary movement
• Primary (somatic) motor cortex in
precentral gyrus
• Premotor cortex anterior to precentral
gyrus
• Broca's area anterior to inferior premotor
area
• Frontal eye field within and anterior to
premotor cortex; superior to Broca's area
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Taste
Motor association
cortex
Primary sensory
cortex
Sensory
association cortex
Vision
Hearing
Multimodal association
cortex
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
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
© 2013 Pearson Education, Inc.
Frontal Eye Field
• Controls voluntary eye movements
© 2013 Pearson Education, Inc.
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
© 2013 Pearson Education, Inc.
Taste
Motor association
cortex
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
© 2013 Pearson Education, Inc.
Motor association
cortex
Primary sensory
cortex
Uncus
Calcarine
sulcus
Parahippocampal
gyrus
Sensory
association cortex
Primary
visual cortex
Multimodal association
cortex
Sensory Areas of Cerebral Cortex
• Conscious awareness of sensation
• Occur in parietal, insular, temporal, and
occipital lobes
• Primary
somatosensory cortex
• Somatosensory
association cortex
• Visual areas
• Auditory areas
© 2013 Pearson Education, Inc.
•
•
•
•
Vestibular cortex
Olfactory cortex
Gustatory cortex
Visceral sensory
area
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
Visual Areas
• Primary visual (striate) cortex
– Extreme posterior tip of occipital lobe
– Most buried in calcarine sulcus of occipital
lobe
– Receives visual information from retinas
© 2013 Pearson Education, Inc.
Visual Areas
• Visual association area
– Surrounds primary visual cortex
– Uses past visual experiences to interpret
visual stimuli (e.g., color, form, and
movement)
• E.g., ability to recognize faces
– Complex processing involves entire posterior
half of cerebral hemispheres
© 2013 Pearson Education, Inc.
Auditory 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
© 2013 Pearson Education, Inc.
PowerPoint® Lecture Slides
prepared by
Barbara Heard,
Atlantic Cape Community
Ninth Edition
College
Human Anatomy & Physiology
CHAPTER
12
The Central
Nervous
System: Part B
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Lateralization of Cortical Function
• Hemispheres almost identical
• Lateralization - division of labor between
hemispheres
• Cerebral dominance - hemisphere
dominant for language (left hemisphere 90% people)
© 2013 Pearson Education, Inc.
Lateralization of Cortical Function
• Left hemisphere
– Controls language, math, and logic
• Right hemisphere
– Visual-spatial skills, intuition, emotion, and
artistic and musical skills
• Hemispheres communicate almost
instantaneously via fiber tracts and
functional integration
© 2013 Pearson Education, Inc.
Diencephalon
• Three paired structures
– Thalamus
– Hypothalamus
– Epithalamus
• Encloses third ventricle
PLAY
Animation: Rotatable brain (sectioned)
© 2013 Pearson Education, Inc.
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
Corpora
quadrigemina Midbrain
Cerebral
aqueduct
Pituitary gland
Mammillary
body
Pons
Medulla
oblongata
Spinal cord
© 2013 Pearson Education, Inc.
Epithalamus
Arbor vitae (of cerebellum)
Fourth ventricle
Choroid plexus
Cerebellum
Thalamic Function
• 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
© 2013 Pearson Education, Inc.
Hypothalamic Function
• Controls autonomic nervous system (e.g.,
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
© 2013 Pearson Education, Inc.
Hypothalamic Function
• Regulates body temperature –
sweating/shivering
• Regulates hunger and satiety in response
to nutrient blood levels or hormones
• Regulates water balance and thirst
© 2013 Pearson Education, Inc.
Hypothalamic Function
• Regulates sleep-wake cycles
– Suprachiasmatic nucleus (biological clock)
• Controls endocrine system
– Controls secretions of anterior pituitary gland
– Produces posterior pituitary hormones
© 2013 Pearson Education, Inc.
Epithalamus
• Most dorsal portion of diencephalon; forms
roof of third ventricle
• Pineal gland (body)—extends from
posterior border and secretes melatonin
– Melatonin—helps regulate sleep-wake cycle
© 2013 Pearson Education, Inc.
Brain Stem
• Three regions
– Midbrain
– Pons
– Medulla oblongata
© 2013 Pearson Education, Inc.
Brain Stem
• Similar structure to spinal cord but
contains nuclei embedded in white matter
• Controls automatic behaviors necessary
for survival
• Contains fiber tracts connecting higher
and lower neural centers
• Nuclei associated with 10 of the 12 pairs
of cranial nerves
© 2013 Pearson Education, Inc.
Figure 12.12 Inferior view of the brain, showing the three parts of the brain stem: midbrain, pons, and medulla
oblongata.
Frontal lobe
Olfactory bulb
(synapse point of
cranial nerve I)
Optic chiasma
Optic nerve (II)
Optic tract
Mammillary body
Midbrain
Pons
Temporal
lobe
Medulla
oblongata
Cerebellum
Spinal cord
© 2013 Pearson Education, Inc.
Cerebellum
• 11% of brain mass
• Dorsal to pons and medulla
• Input from cortex, brain stem and sensory
receptors
• Allows smooth, coordinated movements
© 2013 Pearson Education, Inc.
Anatomy of Cerebellum
• Cerebellar hemispheres connected by
vermis
• Folia—transversely oriented gyri
• Each hemisphere has three lobes
– Anterior, posterior, and flocculonodular
• Arbor vitae—treelike pattern of cerebellar
white matter
© 2013 Pearson Education, Inc.
Figure 12.15a Cerebellum.
Anterior lobe
Arbor vitae
Cerebellar
cortex
Pons
Fourth
ventricle
Medulla
oblongata
© 2013 Pearson Education, Inc.
Posterior
lobe
Flocculonodular lobe
Choroid plexus
PowerPoint® Lecture Slides
prepared by
Barbara Heard,
Atlantic Cape Community
Ninth Edition
College
Human Anatomy & Physiology
CHAPTER
12
The Central
Nervous
System:
Part C
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Functional Brain Systems
• Networks of neurons that work together
but span wide areas of brain
– Limbic system
– Reticular formation
© 2013 Pearson Education, Inc.
Brain Wave Patterns and the EEG
• EEG = electroencephalogram
• Records electrical activity that
accompanies brain function
• Measures electrical potential differences
between various cortical areas
© 2013 Pearson Education, Inc.
Figure 12.18 Electroencephalography (EEG) and brain waves.
1-second interval
Alpha waves—awake but relaxed
Beta waves—awake, alert
Theta waves—common in children
Delta waves—deep sleep
Scalp electrodes are used to record
brain wave activity.
© 2013 Pearson Education, Inc.
Brain waves shown in EEGs
fall into four general classes.
Brain Waves
•
•
•
•
Patterns of neuronal electrical activity
Generated by synaptic activity in cortex
Each person's brain waves are unique
Can be grouped into four classes based
on frequency measured as hertz (Hz)
– Alpha, beta, theta, and delta waves
© 2013 Pearson Education, Inc.
Epilepsy
• Victim of epilepsy may lose
consciousness, fall stiffly, and have
uncontrollable jerking
• Epilepsy not associated with intellectual
impairments
• Epilepsy occurs in 1% of population
• Aura (sensory hallucination) may precede
seizure
© 2013 Pearson Education, Inc.
Epileptic Seizures
• Absence seizures (formerly petit mal)
– Mild seizures of young children - expression
goes blank for few seconds
• Tonic-clonic (formerly grand mal)
seizures
– Most severe; last few minutes
– Victim loses consciousness, bones broken
during intense convulsions, loss of bowel and
bladder control, and severe biting of tongue
© 2013 Pearson Education, Inc.
Consciousness
• Conscious perception of sensation
• Voluntary initiation and control of
movement
• Capabilities associated with higher mental
processing (memory, logic, judgment, etc.)
• Loss of consciousness signal that brain
function impaired
– Fainting or syncopy – brief
– Coma – extended period
© 2013 Pearson Education, Inc.
Sleep and Sleep-Wake Cycles
• State of partial unconsciousness from
which person can be aroused by
stimulation
• Two major types of sleep (defined by EEG
patterns)
– Non-rapid eye movement (NREM) sleep
– Rapid eye movement (REM) sleep
© 2013 Pearson Education, Inc.
Importance of Sleep
• Slow-wave sleep (NREM stages 3 and 4)
presumed to be restorative stage
• People deprived of REM sleep become
moody and depressed
• REM sleep may be reverse learning
process where superfluous information
purged from brain
• Daily sleep requirements decline with age
• Stage 4 sleep declines steadily and may
disappear after age 60
© 2013 Pearson Education, Inc.
Sleep Disorders
• Narcolepsy
– Abrupt lapse into sleep from awake state
– Often have cataplexy
• Sudden loss of voluntary muscle control
– Orexins ("wake-up" chemicals from
hypothalamus) destroyed by immune system
• Key to possible treatment
© 2013 Pearson Education, Inc.
Sleep Disorders
• Insomnia
– Chronic inability to obtain amount or quality of
sleep needed
– May be treated by blocking orexin action
• Sleep apnea
– Temporary cessation of breathing during
sleep
– Causes hypoxia
© 2013 Pearson Education, Inc.
Memory
• Storage and retrieval of information
• Two stages of storage
– Short-term memory (STM, or working
memory)—temporary holding of information;
limited to seven or eight pieces of information
– Long-term memory (LTM) has limitless
capacity
© 2013 Pearson Education, Inc.
Protection of the Brain
•
•
•
•
Bone (skull)
Membranes (meninges)
Watery cushion (cerebrospinal fluid)
Blood brain barrier
© 2013 Pearson Education, Inc.
Meninges
• Cover and protect CNS
• Protect blood vessels and enclose venous
sinuses
• Contain cerebrospinal fluid (CSF)
• Form partitions in skull
© 2013 Pearson Education, Inc.
Meninges
• Three layers
– Dura mater
– Arachnoid mater
– Pia mater
• Meningitis
– Inflammation of meninges
© 2013 Pearson Education, Inc.
Figure 12.22 Meninges: dura mater, arachnoid mater, and pia mater.
Skin of scalp
Periosteum
Superior sagittal
sinus
Subdural
space
Subarachnoid
space
© 2013 Pearson Education, Inc.
Bone of skull
Dura mater
• Periosteal layer
• Meningeal layer
Arachnoid mater
Pia mater
Arachnoid villus
Blood vessel
Falx cerebri
(in longitudinal
fissure only)
Dura Mater
• Strongest meninx
• Two layers of fibrous connective tissue
(around brain) separate to form dural
venous sinuses
© 2013 Pearson Education, Inc.
Figure 12.23b Dural septa and dural venous sinuses.
Superior
sagittal sinus
Falx cerebri
Parietal
bone
Scalp
Occipital lobe
Tentorium
cerebelli
Falx
cerebelli
Cerebellum
Arachnoid
mater over
medulla oblongata
Posterior dissection
© 2013 Pearson Education, Inc.
Dura mater
Transverse
sinus
Temporal
bone
Arachnoid Mater
• Middle layer with weblike extensions
• Separated from dura mater by subdural
space
• Subarachnoid space contains CSF and
largest blood vessels of brain
• Arachnoid villi protrude into superior
sagittal sinus and permit CSF
reabsorption
© 2013 Pearson Education, Inc.
Figure 12.22 Meninges: dura mater, arachnoid mater, and pia mater.
Skin of scalp
Periosteum
Superior sagittal
sinus
Subdural
space
Subarachnoid
space
© 2013 Pearson Education, Inc.
Bone of skull
Dura mater
• Periosteal layer
• Meningeal layer
Arachnoid mater
Pia mater
Arachnoid villus
Blood vessel
Falx cerebri
(in longitudinal
fissure only)
Pia Mater
• Delicate vascularized connective tissue
that clings tightly to brain
© 2013 Pearson Education, Inc.
Cerebrospinal Fluid (CSF)
• Composition
– Watery solution formed from blood plasma
• Less protein and different ion concentrations than
plasma
– Constant volume
© 2013 Pearson Education, Inc.
Cerebrospinal Fluid (CSF)
• Functions
– Gives buoyancy to CNS structures
• Reduces weight by 97%
– Protects CNS from blows and other trauma
– Nourishes brain and carries chemical signals
© 2013 Pearson Education, Inc.
Figure 12.24a Formation, location, and circulation of CSF.
Slide 1
4
Superior
sagittal sinus
Arachnoid villus
Choroid plexus
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater
1
Interventricular
foramen
Third ventricle
Right lateral ventricle
(deep to cut)
3
Cerebral aqueduct
Lateral aperture
Fourth ventricle
Median aperture
Central canal
of spinal cord
(a) CSF circulation
© 2013 Pearson Education, Inc.
Choroid plexus
of fourth ventricle
2
1 The choroid plexus of each
Ventricle produces CSF.
2 CSF flows through the ventricles
and into the subarachnoid space via
the median and lateral apertures.
3 CSF flows through the
subarachnoid space.
4 CSF is absorbed into the dural
venous sinuses via the arachnoid villi.
Choroid Plexuses
• Hang from roof of each ventricle; produce
CSF at constant rate; keep in motion
– Clusters of capillaries enclosed by pia mater
and layer of ependymal cells
• Ependymal cells use ion pumps to control
composition of CSF and help cleanse CSF
by removing wastes
• Normal volume ~ 150 ml; replaced every 8
hours
© 2013 Pearson Education, Inc.
Hydrocephalus
• Obstruction blocks CSF circulation or
drainage
• Unfused skull bones of newborn allow
enlargement of head
• Brain damage in adult due to rigid adult
skull
• Treated by draining with ventricular shunt
to abdominal cavity
© 2013 Pearson Education, Inc.
Figure 12.25 Hydrocephalus in a newborn.
© 2013 Pearson Education, Inc.
Blood Brain Barrier
• Helps maintain stable environment for
brain
• Separates neurons from some bloodborne
substances
© 2013 Pearson Education, Inc.
Blood Brain Barrier: Functions
• Selective barrier
– Allows nutrients to move by facilitated 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
• Absent in some areas, e.g., vomiting center and
hypothalamus, where necessary to monitor
chemical composition of blood
© 2013 Pearson Education, Inc.
Homeostatic Imbalances of the Brain
• Traumatic brain injuries
– Concussion—temporary alteration in function
– Contusion—permanent damage
– Subdural or subarachnoid hemorrhage—
may force brain stem through foramen
magnum, resulting in death
– Cerebral edema—swelling of brain
associated with traumatic head injury
© 2013 Pearson Education, Inc.
Homeostatic Imbalances of the Brain
• Cerebrovascular accidents (CVAs or strokes)
– Ischemia
• Tissue deprived of blood supply; brain tissue dies, e.g.,
blockage of cerebral artery by blood clot
– Hemiplegia (paralysis on one side), or sensory and
speech deficits
– Transient ischemic attacks (TIAs)—temporary
episodes of reversible cerebral ischemia
– Tissue plasminogen activator (TPA) is only
approved treatment for stroke
© 2013 Pearson Education, Inc.
Homeostatic Imbalances of the Brain
• Degenerative brain disorders
– Alzheimer's disease (AD): a progressive
degenerative disease of brain that results in
dementia
• Memory loss, short attention span, disorientation,
eventual language loss, irritable, moody, confused,
hallucinations
• Plaques of beta-amyloid peptide form in brain
– Toxic effects may involve prion proteins
• Neurofibrillary tangles inside neurons kill them
• Brain shrinks
© 2013 Pearson Education, Inc.
Homeostatic Imbalances of the Brain
• Parkinson's disease
– Degeneration of dopamine-releasing neurons
of substantia nigra
– Basal nuclei deprived of dopamine become
overactive  tremors at rest
– Cause unknown
• Mitochondrial abnormalities or protein degradation
pathways?
– Treatment with L-dopa; deep brain
stimulation; gene therapy; research into stem
cell transplants promising
© 2013 Pearson Education, Inc.
Homeostatic Imbalances of the Brain
• Huntington's disease
– Fatal hereditary disorder
– Caused by accumulation of protein huntingtin
• Leads to degeneration of basal nuclei and cerebral cortex
• Initial symptoms wild, jerky "flapping"
movements
• Later marked mental deterioration
• Treated with drugs that block dopamine effects
• Stem cell implant research promising
© 2013 Pearson Education, Inc.
PowerPoint® Lecture Slides
prepared by
Barbara Heard,
Atlantic Cape Community
Ninth Edition
College
Human Anatomy & Physiology
CHAPTER
12
The Central
Nervous
System:
Part D
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Spinal Cord: Gross Anatomy and Protection
• Location
– Begins at the foramen magnum
– Ends at L1 or L2 vertebra
• Functions
– Provides two-way communication to and from
brain
– Contains spinal reflex centers
© 2013 Pearson Education, Inc.
Spinal Cord: Gross Anatomy and Protection
• Bone, meninges, and CSF
• Epidural space
– Cushion of fat and network of veins in space
between vertebrae and spinal dura mater
• CSF in subarachnoid space
• Dural and arachnoid membranes extend to
sacrum, beyond end of cord at L1 or L2
– Site of lumbar puncture or tap
© 2013 Pearson Education, Inc.
Spinal Cord: Gross Anatomy and Protection
• Terminates in conus medullaris
• Filum terminale extends to coccyx
– Fibrous extension of conus covered with pia
mater
– Anchors spinal cord
• Denticulate ligaments
– Extensions of pia mater that secure cord to
dura mater
© 2013 Pearson Education, Inc.
Figure 12.27 Diagram of a lumbar tap.
T12
L5
Ligamentum
flavum
Lumbar puncture
needle entering
subarachnoid
space
L4
Supraspinous
ligament
Filum
terminale
L5
S1
Intervertebral
disc
© 2013 Pearson Education, Inc.
Arachnoid
mater
Dura
mater
Cauda equina
in subarachnoid
space
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
© 2013 Pearson Education, Inc.
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
arachnoid mater are cut open and reflected laterally.
Figure 12.26b Gross structure of the spinal cord, dorsal view.
Cranial
dura mater
Terminus of
medulla
oblongata
of brain
Sectioned
pedicles of
cervical
vertebrae
Spinal nerve
rootlets
Dorsal
median sulcus
of spinal cord
Cervical spinal cord.
© 2013 Pearson Education, Inc.
Figure 12.26c Gross structure of the spinal cord, dorsal view.
Spinal cord
Vertebral
arch
Denticulate
ligament
Denticulate
ligament
Dorsal
median
sulcus
Arachnoid
mater
Dorsal root
Spinal dura
mater
Thoracic spinal cord, showing
denticulate ligaments.
© 2013 Pearson Education, Inc.
Spinal Cord
• Spinal nerves (Part of PNS)
– 31 pairs
• Cervical and lumbosacral enlargements
– Nerves serving upper and lower limbs emerge
here
• Cauda equina
– Collection of nerve roots at inferior end of
vertebral canal
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Cross-sectional Anatomy
• Two lengthwise grooves partially divide
cord into right and left halves
– Ventral (anterior) median fissure
– Dorsal (posterior) median sulcus
• Gray commissure—connects masses of
gray matter; encloses central canal
© 2013 Pearson Education, Inc.
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.
Gray Matter
• Dorsal horns - interneurons that receive
somatic and visceral sensory input
• Ventral horns - some interneurons; somatic
motor neurons; axons exit cord via ventral roots
• Lateral horns (only in thoracic and superior
lumbar regions) - sympathetic neurons
• Dorsal roots – sensory input to cord
• Dorsal root (spinal) ganglia—cell bodies of
sensory neurons
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White Matter
• Divided into three white columns
(funiculi) on each side
– Dorsal (posterior), lateral, and ventral
(anterior)
• Each spinal tract composed of axons with
similar destinations and functions
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Spinal Cord Trauma
• Functional losses
– Paresthesias
• Sensory loss
– Paralysis
• Loss of motor function
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Spinal Cord Trauma
• Flaccid paralysis—severe damage to
ventral root or ventral horn cells
– Impulses do not reach muscles; there is no
voluntary or involuntary control of muscles
– Muscles atrophy
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Spinal Cord Trauma
• Spastic paralysis—damage to upper
motor neurons of primary motor cortex
– Spinal neurons remain intact; muscles are
stimulated by reflex activity
– No voluntary control of muscles
– Muscles often shorten permanently
© 2013 Pearson Education, Inc.
Spinal Cord Trauma
• Transection
– Cross sectioning of spinal cord at any level
– Results in total motor and sensory loss in
regions inferior to cut
– Paraplegia—transection between T1 and L1
– Quadriplegia—transection in cervical region
• Spinal shock – transient period of
functional loss caudal to lesion
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Assessing CNS Dysfunction
• Reflex tests
• Imaging techniques
– CT, MRI, PET, radiotracer dyes for
Alzheimer's, ultrasound, cerebral angiography
© 2013 Pearson Education, Inc.