Central Nervous System: CNS

Содержание

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The Spinal Cord

Foramen magnum to L1 or L2
Runs through the vertebral

The Spinal Cord Foramen magnum to L1 or L2 Runs through the
canal of the vertebral column
Functions
Sensory and motor innervation of entire body inferior to the head through the spinal nerves
Two-way conduction pathway between the body and the brain
Major center for reflexes

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Fetal 3rd month: ends at coccyx
Birth: ends at L3
Adult position at approx

Fetal 3rd month: ends at coccyx Birth: ends at L3 Adult position
L1-2 during childhood
End: conus medullaris
This tapers into filum terminale of connective tissue, tethered to coccyx
Spinal cord segments are superior to where their corresponding spinal nerves emerge through intervetebral foramina (see also fig 17.5, p 288)
Denticulate ligaments: lateral shelves of pia mater anchoring to dura (meninges: more later)

Spinal cord

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Spinal nerves

Part of the peripheral nervous system
31 pairs attach through dorsal and

Spinal nerves Part of the peripheral nervous system 31 pairs attach through
ventral nerve roots
Lie in intervertebral foramina

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Spinal nerves continued

Divided based on vertebral locations
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Cauda

Spinal nerves continued Divided based on vertebral locations 8 cervical 12 thoracic
equina (“horse’s tail”): collection of nerve roots at inferior end of vertebral canal

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Spinal nerves continued

Note: cervical spinal nerves exit from above the respective vertebra
Spinal

Spinal nerves continued Note: cervical spinal nerves exit from above the respective
nerve root 1 from above C1
Spinal nerve root 2 from between C1 and C2, etc.
Clinically, for example when referring to disc impingement, both levels of vertebra mentioned, e.g. C6-7 disc impinging on root 7
Symptoms usually indicate which level

More about spinal nerves in the peripheral nervous system lecture

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Protection:

Bone
Meninges
CSF (cerebrospinal fluid)

3 meninges:
dura mater (outer)
arachnoid mater (middle)
pia mater

Protection: Bone Meninges CSF (cerebrospinal fluid) 3 meninges: dura mater (outer) arachnoid
(inner)
3 potential spaces
epidural: outside dura
subdural: between dura & arachnoid
subarachnoid: deep to arachnoid

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Dura mater
Arachnoid mater
Pia mater

Spinal cord coverings and spaces

http://www.eorthopod.com/images/ContentImages/pm/pm_general_esi/pmp_general_esi_epidural_space.jpg

Dura mater Arachnoid mater Pia mater Spinal cord coverings and spaces http://www.eorthopod.com/images/ContentImages/pm/pm_general_esi/pmp_general_esi_epidural_space.jpg

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LP (lumbar puncure) = spinal tap (needle introduced into subdural space to collect

LP (lumbar puncure) = spinal tap (needle introduced into subdural space to
CSF)

Lumbar spine needs to be flexed so can go between spinous processes

Epidural space is external to dura
Anesthestics are often injected into epidural space
Injection into correct space is vital; mistakes can be lethal

Originally thought to be a narrowOriginally thought to be a narrow fluidOriginally thought to be a narrow fluid-filled intervalOriginally thought to be a narrow fluid-filled interval between the duralOriginally thought to be a narrow fluid-filled interval between the dural and arachnoidOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificialOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial spaceOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separationOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the duraOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the resultOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of traumaOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologicOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic processOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthyOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthy stateOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthy state, the arachnoid is attached to the dura and a naturally occurring subduralOriginally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthy state, the arachnoid is attached to the dura and a naturally occurring subdural space is not present. http://cancerweb.ncl.ac.uk/cgi-bin/omd?subdural+space

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Spinal cord anatomy

Posterior median sulcus (“p”)
Anterior median fissure (“a”)
White matter (yellow here)
Gray

Spinal cord anatomy Posterior median sulcus (“p”) Anterior median fissure (“a”) White
matter (brown here)

“p”

“a”

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Gray/White in spinal cord

Hollow central cavity (“central canal”)
Gray matter surrounds cavity
White matter

Gray/White in spinal cord Hollow central cavity (“central canal”) Gray matter surrounds
surrounds gray matter (white: ascending and descending tracts of axons)
“H” shaped on cross section
Dorsal half of “H”: cell bodies of interneurons
Ventral half of “H”: cell bodies of motor neurons
No cortex (as in brain)

Dorsal (posterior)

white

gray

Ventral (anterior)

Central canal______

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Spinal cord anatomy

Gray commissure with central canal
Columns of gray running the length

Spinal cord anatomy Gray commissure with central canal Columns of gray running
of the spinal cord
Posterior (dorsal) horns (cell bodies of interneurons)
Anterior (ventral) horns (cell bodies of motor neurons)
Lateral horns in thoracic and superior lumbar cord

*

*

*

*

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White matter of the spinal cord (myelinated and unmyelinated axons)

Ascending fibers: sensory information

White matter of the spinal cord (myelinated and unmyelinated axons) Ascending fibers:
from sensory neurons of body up to brain
Descending fibers: motor instructions from brain to spinal cord
Stimulates contraction of body’s muscles
Stimumulates secretion from body’s glands
Commissural fibers: white-matter fibers crossing from one side of cord to the other
Most pathways cross (or decussate) at some point
Most synapse two or three times along the way, e.g. in brain stem, thalamus or other

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The Brain: embryonic development

Develops from neural tube
Brain subdivides into
Forebrain
Midbrain
Hindbrain
These further divide,

The Brain: embryonic development Develops from neural tube Brain subdivides into Forebrain
each with a fluid filled region: ventricle, aqueduct or canal
Spinal cord also has a canal
Two major bends, or flexures, occur (midbrain and cervical)

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Brain development

Learn forebrain, midbrain and hindbrain in (b)
See next color

Brain development Learn forebrain, midbrain and hindbrain in (b) See next color
coded pics in reference to (d)
Learn (e)
Encephalos means brain (otherwise you don’t need to learn “c”)

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Space restrictions force cerebral hemispheres to grow posteriorly over rest of brain,

Space restrictions force cerebral hemispheres to grow posteriorly over rest of brain,
enveloping it
Cerebral hemispheres grow into horseshoe shape (b and c)
Continued growth causes creases, folds and wrinkles

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Anatomical classification

Cerebral hemispheres
Diencephalon
Thalamus
Hypothalamus
Brain stem
Midbrain
Pons
Medulla
Cerebellum
Spinal cord

Anatomical classification Cerebral hemispheres Diencephalon Thalamus Hypothalamus Brain stem Midbrain Pons Medulla Cerebellum Spinal cord

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Parts of Brain

Cerebrum
Diencephalon
Brainstem
Cerebellum

Parts of Brain Cerebrum Diencephalon Brainstem Cerebellum

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Usual pattern of gray/white in CNS

White exterior to gray
Gray surrounds hollow central

Usual pattern of gray/white in CNS White exterior to gray Gray surrounds
cavity
Two regions with additional gray called “cortex”
Cerebrum: “cerebral cortex”
Cerebellum: “cerebellar cortex”

_________________

____________________________

_____________________________

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Gray and White Matter

Like spinal cord but with another layer of gray

Gray and White Matter Like spinal cord but with another layer of
outside the white
Called cortex
Cerebrum and cerebellum have
Inner gray: “brain nuclei” (not cell nuclei)
Clusters of cell bodies
Remember, in PNS clusters of cell bodies were called “ganglia”

More words: brains stem is caudal (toward tail)
to the more rostral (noseward) cerebrum

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Ventricles

Central cavities expanded
Filled with CSF (cerebrospinal fluid)
Lined by ependymal cells (these cells

Ventricles Central cavities expanded Filled with CSF (cerebrospinal fluid) Lined by ependymal
lining the choroid plexus make the CSF: see later slides)
Continuous with each other and central canal of spinal cord

In the following slides, the ventricles are the parts colored blue

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Lateral ventricles
Paired, horseshoe shape
In cerebral hemispheres
Anterior are close, separated only by thin

Lateral ventricles Paired, horseshoe shape In cerebral hemispheres Anterior are close, separated
Septum pellucidum

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Third ventricle
In diencephalon
Connections
Interventricular foramen
Cerebral aqueduct

Third ventricle In diencephalon Connections Interventricular foramen Cerebral aqueduct

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Fourth ventricle
In the brainstem
Dorsal to pons and top of medulla
Holes connect it

Fourth ventricle In the brainstem Dorsal to pons and top of medulla
with subarachnoid space

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Subarachnoid space

Aqua blue in this pic
Under thick coverings of brain
Filled with CSF

Subarachnoid space Aqua blue in this pic Under thick coverings of brain
also
Red: choroid plexus
(more later)

________

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Surface anatomy

Gyri (plural of gyrus)
Elevated ridges
Entire surface
Grooves separate gyri
A sulcus is

Surface anatomy Gyri (plural of gyrus) Elevated ridges Entire surface Grooves separate
a shallow groove (plural, sulci)
Deeper grooves are fissures

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Gyri (plural of gyrus)
Elevated ridges
Entire surface
Grooves separate gyri
A sulcus is a shallow

Gyri (plural of gyrus) Elevated ridges Entire surface Grooves separate gyri A
groove (plural, sulci)
Deeper grooves are fissures

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Parts of Brain

Cerebrum
Diencephalon
Brainstem
Cerebellum

Parts of Brain Cerebrum Diencephalon Brainstem Cerebellum

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simplified…

Back of brain: perception
Top of brain: movement
Front of brain: thinking

simplified… Back of brain: perception Top of brain: movement Front of brain: thinking

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Cerebral hemispheres

Lobes: under bones of same name
Frontal
Parietal
Temporal
Occipital
Plus: Insula (buried deep in lateral

Cerebral hemispheres Lobes: under bones of same name Frontal Parietal Temporal Occipital
sulcus)

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Cerebral hemispheres: note lobes

Divided by longitudinal fissure into right & left sides
Central

Cerebral hemispheres: note lobes Divided by longitudinal fissure into right & left
sulcus divides frontal from parietal lobes

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Lateral sulcus separates temporal lobe from parietal lobe
Parieto-occipital sulcus divides occipital and

Lateral sulcus separates temporal lobe from parietal lobe Parieto-occipital sulcus divides occipital
parietal lobes (not seen from outside)
Transverse cerebral fissure separates cerebral hemispheres from cerebellum

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coronal section

Note: longitudinal fissure, lateral sulcus, insula
Note: cerebral cortex (external sheet

coronal section Note: longitudinal fissure, lateral sulcus, insula Note: cerebral cortex (external
of gray), cerebral white, deep gray (basal ganglia)

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Cerebral cortex

Executive functioning capability
Gray matter: of neuron cell bodies, dendrites, short unmyelinated

Cerebral cortex Executive functioning capability Gray matter: of neuron cell bodies, dendrites,
axons
100 billion neurons with average of 10,000 contacts each
No fiber tracts (would be white)
2-4 mm thick (about 1/8 inch)
Brodmann areas (historical: 52 structurally different areas given #s)
Neuroimaging: functional organization
(example later)

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Prenatal life: genes are responsible for creating the architecture of the brain
Cortex

Prenatal life: genes are responsible for creating the architecture of the brain
is the last to develop and very immature at birth
Birth: excess of neurons but not inter-connected
1st month of life: a million synapses/sec are made; this is genetic
1st 3 years of life: synaptic overgrowth (connections)
After this the density remains constant though some grow, some die
Preadolescence: another increase in synaptic formation
Adolescence until 25: brain becomes a reconstruction site
Connections important for self-regulation (in prefrontal cortex) are being remodeled: important for a sense of wholeness
Causes personal turbulence
Susceptible to stress and toxins (like alcohol and drugs) during these years; affects the rest of one’s life
The mind changes the brain (throughout life)
Where brain activation occurs, synapses happen
When pay attention & focus mind, neural firing occurs and brain structure changes (synapses are formed)
Human connections impact neural connections (ongoing experiences and learning include the interpersonal ones)

adapted from Dr. Daniel Siegel, UCLA

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Cerebral cortex

All the neurons are interneurons
By definition confined to the CNS
They have

Cerebral cortex All the neurons are interneurons By definition confined to the
to synapse somewhere before the info passes to the peripheral nerves
Three kinds of functional areas
Motor areas: movement
Sensory areas: perception
Association areas: integrate diverse information to enable purposeful action

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Sensory areas Posterior to central sulcus

Primary somatosensory cortex: postcentral gyrus of parietal

Sensory areas Posterior to central sulcus Primary somatosensory cortex: postcentral gyrus of
lobe (allows conscious awareness of sensation and the ability to localize it: where the sensation is from)
Somatosensory association area: behind it (understanding of what is being felt: the meaning of it)

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From special sense organs

Sight: occipital lobe
Primary visual cortex (17)
Handles info from contralateral

From special sense organs Sight: occipital lobe Primary visual cortex (17) Handles
retina (right ½ of visual field is on left side)
Map of visual space
If damaged: functionally blind because no conscious awareness of sight
Visual association area (18 & 19)
Face recognition is usually on the right side
Hearing: temporal lobe
Primary auditory area (41)
Auditory association area (22)

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Refer back to this labeled version as needed

Refer back to this labeled version as needed

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Smell (olfactory sense): uncus
Deep in temporal lobe along medial surface

Smell (olfactory sense): uncus Deep in temporal lobe along medial surface

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fMRI: functional magnetic resonance imaging
Cerebral cortex of person speaking & hearing
Activity (blood

fMRI: functional magnetic resonance imaging Cerebral cortex of person speaking & hearing
flow) in posterior frontal and superior temporal lobes respectively

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Motor areas Anterior to central sulcus

Primary motor area
Precentral gyrus of frontal lobe

Motor areas Anterior to central sulcus Primary motor area Precentral gyrus of
(4)
Conscious or voluntary movement of skeletal muscles

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Primary motor area continued
Precentral gyrus of frontal lobe
Precise, conscious or voluntary movement

Primary motor area continued Precentral gyrus of frontal lobe Precise, conscious or
of skeletal muscles
Large neurons called pyramidal cells
Their axons: form massive pyramidal or corticospinal tracts
Decend through brain stem and spinal cord
Cross to contralateral (the other) side in brainstem
Therefore: right side of the brain controls the left side of the body, and the left side of the brain controls the right side of the body

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Motor areas – continued

Broca’s area (44): specialized motor speech area
Base of

Motor areas – continued Broca’s area (44): specialized motor speech area Base
precentral gyrus just above lateral sulcus in only one hemisphere, usually left
Word articulation: the movements necessary for speech
Damage: can understand but can’t speak; or if can still speak, words are right but difficult to understand

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Motor areas – continued

Premotor cortex (6): complex movements asociated with highly processed

Motor areas – continued Premotor cortex (6): complex movements asociated with highly
sensory info; also planning of movements
Frontal eye fields (inferior 8): voluntary movements of eyes

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Homunculus – “little man”

Body map: human body spatially represented
Where on cortex; upside

Homunculus – “little man” Body map: human body spatially represented Where on cortex; upside down
down

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Association Areas

Remember…
Three kinds of functional areas (cerebrum)
Motor areas: movement
Sensory areas: perception
Association areas:

Association Areas Remember… Three kinds of functional areas (cerebrum) Motor areas: movement
everything else

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Association Areas

Tie together different kinds of sensory input
Associate new input with memories
Is

Association Areas Tie together different kinds of sensory input Associate new input
to be renamed “higher-order processing“ areas

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Prefrontal cortex: cognition

Executive functioning
e.g. multiple step problem solving requiring temporary storage of

Prefrontal cortex: cognition Executive functioning e.g. multiple step problem solving requiring temporary
info (working memory)

This area is remodeled during adolescence until the age of 25 and is very important for well-being; it coordinates the brain/body and inter-personal world as a whole
Social skills
Appreciating humor
Conscience
Mood
Mental flexibility
Empathy

Intellect
Abstract ideas
Judgment
Personality
Impulse control
Persistence
Complex
Reasoning
Long-term planning

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Wernicke’s area

Junction of parietal and temporal lobes
One hemisphere only, usually left
(Outlined by

Wernicke’s area Junction of parietal and temporal lobes One hemisphere only, usually
dashes)
Pathology: comprehension impaired for written and spoken language: output fluent and voluminous
but incoherent
(words understandable
but don’t make sense;
as opposed to the
opposite with Broca’s
area)

Region involved in recognizing and understanding spoken words

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Cerebral white matter

Extensive communication
Areas of cortex with each other
Areas of cortex with

Cerebral white matter Extensive communication Areas of cortex with each other Areas
brain stem and spinal cord
Via (mostly) myelinated axon fibers bundled into tracts
Commissures
Association fibers
Projection fibers

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Commissures: interconnect right and left hemispheres so can act as a whole
Corpus

Commissures: interconnect right and left hemispheres so can act as a whole
callosum is largest
Association fibers: connect different parts of the same hemisphere; can be long or short

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Projection fibers: run vertically
Cerebral cortex running down (with motor instructions)
Or ascend to

Projection fibers: run vertically Cerebral cortex running down (with motor instructions) Or
cerebral cortex from below (sensory info to cortex)

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Corona radiata: spray of projection fibers
From precentral (motor) gyrus
Combines with sensory fibers

Corona radiata: spray of projection fibers From precentral (motor) gyrus Combines with
traveling to sensory cortex
Form a band of fibers called internal capsule*

___________Sensory input to brain

Motor output from brain__________

*

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Projection fibers
Corona radiata: fanning out of the fibers
Internal capsule: bundled, pass

Projection fibers Corona radiata: fanning out of the fibers Internal capsule: bundled,
down
Commisure
Corpus callosum: connects right and left hemispheres
Decussation: crossing of pyramidal tracts

_________________

___________________

________________

_____________________

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Cerebral hemisphere gray
Cortex – already reviewed
Basal forebrain nuclei: near hypothalamus - related

Cerebral hemisphere gray Cortex – already reviewed Basal forebrain nuclei: near hypothalamus
to arousal, learning, memory and motor control
“Islands” of gray: nuclei (clusters of neuron cell bodies)
Important group is basal ganglia
(here “ganglia” doesn’t refer to PNS cell bodies)

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Basal ganglia

Subcortical motor nuclei
Part of “extrapyramidal system”
Cooperate with cerebral cortex in controlling

Basal ganglia Subcortical motor nuclei Part of “extrapyramidal system” Cooperate with cerebral
movements
Most important ones: caudate nucleus, lentiform nucleus composed of putamen and globus pallidus
Not part of basal forebrain nuclei (which are related to arousal, learning , memory and motor control)

Transverse section

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Internal capsule passes between diencephalon and basal ganglia to give them a

Internal capsule passes between diencephalon and basal ganglia to give them a
striped appearance
Caudate and lentiform sometimes called corpus striatum because of this

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Basal ganglia

Cooperate with cerebral cortex in controlling movements
Communicate with cerebral cortex, receive

Basal ganglia Cooperate with cerebral cortex in controlling movements Communicate with cerebral
input from cortical areas, send most of output back to motor cortex through thalamus
Involved with stopping/starting & intensity of movements
“Dyskinesias” – “bad movements”
Parkinson’s disease: loss of inhibition from substantia nigra of midbrain – everything slows down
Huntington disease: overstimulation (“choreoathetosis”) – degeneration of corpus striatum which inhibits; eventual degeneration of cerebral cortex (AD; genetic test available)
Extrapyramidal drug side effects: “tardive dyskinesia”
Can be irreversible; haloperidol, thorazine and similar drugs

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Basal ganglia

Note relationship of basal ganglia to thalamus and ventricles

Transverse section again

Basal ganglia Note relationship of basal ganglia to thalamus and ventricles Transverse section again

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Diencephalon (part of forebrain) Contains dozens of nuclei of gray matter

Thalamus
Hypothalamus
Epithalamus (mainly pineal)

Diencephalon (part of forebrain) Contains dozens of nuclei of gray matter Thalamus Hypothalamus Epithalamus (mainly pineal)

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Thalamus (egg shaped; means inner room)
Two large lobes of gray matter (over

Thalamus (egg shaped; means inner room) Two large lobes of gray matter
a dozen nuclei)
Laterally enclose the 3rd ventricle
Gateway to cerebral cortex: every part of brain that communicates with cerebral cortex relays signals through a nucleus in the thalamus (e.g. certain nucleus for info from retina, another from ears, etc.)
Processing (editing) occurs also in thalamus

Coronal section

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Hypothalamus Forms inferolateral walls of 3rd ventricle Many named nuclei

Coronal section

Hypothalamus Forms inferolateral walls of 3rd ventricle Many named nuclei Coronal section

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Diencephalon – surface anatomy Hypothalamus is between optic chiasma to and including mamillary

Diencephalon – surface anatomy Hypothalamus is between optic chiasma to and including
bodies

Olfactory bulbs
Olfactory tracts
Optic nerves
Optic chiasma
(partial cross over)
Optic tracts
Mammillary bodies

(looking at brain from below)

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Diencephalon – surface anatomy Hypothalamus is between optic chiasma to and including mamillary

Diencephalon – surface anatomy Hypothalamus is between optic chiasma to and including
bodies

(from Ch 14: cranial nerve diagram)

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Cranial Nerve names

Identify as many as you can when looking at model

Cranial Nerve names Identify as many as you can when looking at
and sheep brain
(they will be more fully discussed in Chapter 14)

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Hypothalamus

“Below thalamus”
Main visceral control center
Autonomic nervous system (peripheral motor neurons controlling smooth

Hypothalamus “Below thalamus” Main visceral control center Autonomic nervous system (peripheral motor
and cardiac muscle and gland secretions): heart rate, blood pressure, gastrointestinal tract, sweat and salivary glands, etc.
Emotional responses (pleasure, rage, sex drive, fear)
Body temp, hunger, thirst sensations
Some behaviors
Regulation of sleep-wake centers: circadian rhythm (receives info on light/dark cycles from optic nerve)
Control of endocrine system through pituitary gland
Involved, with other sites, in formation of memory

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Hypothalamus (one example of its functioning)

Control of endocrine system through pituitary gland

Hypothalamus (one example of its functioning) Control of endocrine system through pituitary gland

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Epithalamus

Third and most dorsal part of diencephalon
Part of roof of 3rd ventricle
Pineal

Epithalamus Third and most dorsal part of diencephalon Part of roof of
gland or body (unpaired): produces melatonin signaling nighttime sleep
Also a tiny group of nuclei

Coronal section

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Brain Stem

Midbrain
Pons
Medulla oblongata

Rigidly programmed automatic behavior necessary for survival
Passageway for fiber tracts

Brain Stem Midbrain Pons Medulla oblongata Rigidly programmed automatic behavior necessary for
running between cerebrum and spinal cord
Heavily involved with innvervation of face and head (10 of the12 cranial nerves attach to it)

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Brain stem
Midbrain
Pons
Medulla oblongata

Brain stem Midbrain Pons Medulla oblongata

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__Cerebral peduncles____
Contain pyramidal motor tracts

Corpora quadrigemina:

XVisual reflexes
XAuditory reflexes

Midbrain

______Substantia nigra

(degeneration causes Parkingson’s

__Cerebral peduncles____ Contain pyramidal motor tracts Corpora quadrigemina: XVisual reflexes XAuditory reflexes
disease)

_______Periaqueductal gray

(flight/flight; nausea with visceral pain; some cranial nerve nuclei)

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__Middle cerebellar peduncles_

Pons

3 cerebellar peduncles__

Also contains several CN and other nuclei

(one

__Middle cerebellar peduncles_ Pons 3 cerebellar peduncles__ Also contains several CN and
to each of the three parts of the brain stem)

Dorsal view

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Medulla oblongata

Relays sensory info to cerebral cortex and cerebellum
Contains many CN

Medulla oblongata Relays sensory info to cerebral cortex and cerebellum Contains many
and other nuclei
Autonomic centers controlling heart rate, respiratory rhythm, blood pressure; involuntary centers of vomiting, swallowing, etc.

Dorsal view

_______Pyramids

____pyramidal decussation

“Pyramidal”=corticospinal tracts; these are motor tracts which cross over in the decussation. They are named pyramids because they supposedly look like them, and also they originate from “pyramidal” neurons in the motor cortex. The tracts have the name of origin 1st, therefore “corticospinal” tells you they go from the cortex (“cortico-”) to the spinal cord (“-spinal”)
see later slides

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With all the labels….

With all the labels….

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Brain Stem in mid-sagittal plane

Note cerebral aqueduct and fourth ventricle*

*

*

Brain Stem in mid-sagittal plane Note cerebral aqueduct and fourth ventricle* * *

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Cerebellum

Two major hemispheres: three lobes each
Anterior
Posterior
Floculonodular
Vermis: midline lobe connecting hemispheres
Outer cortex

Cerebellum Two major hemispheres: three lobes each Anterior Posterior Floculonodular Vermis: midline
of gray
Inner branching white matter, called “arbor vitae”

Separated from brain stem by 4th ventricle

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Functions of cerebellum

Smooths, coordinates & fine tunes bodily movements
Helps maintain body posture
Helps

Functions of cerebellum Smooths, coordinates & fine tunes bodily movements Helps maintain
maintain equilibrium
How?
Gets info from cerebrum re: movements being planned
Gets info from inner ear re: equilibrium
Gets info from proprioceptors (sensory receptors informing where the parts of the body actually are)
Using feedback, adjustments are made
Also some role in cognition
Damage: ataxia, incoordination, wide-based gait, overshooting, proprioception problems

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Functional brain systems (as opposed to anatomical ones)

Networks of distant neurons that function

Functional brain systems (as opposed to anatomical ones) Networks of distant neurons
together
Limbic system
Reticular formation

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Limbic system (not a discrete structure - includes many brain areas)

Most important

Limbic system (not a discrete structure - includes many brain areas) Most
parts:
Hipocampus
Amygdala
Cingulate gyrus
Orbitofrontal cortex (not labeled; is behind eyes - part of the prefrontal cortex but connects closely)

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Limbic system continued

Called the “emotional” brain
Is essential for flexible, stable, adaptive functioning
Links

Limbic system continued Called the “emotional” brain Is essential for flexible, stable,
different areas so integration can occur
Integration: separate things are brought together as a whole
Processes emotions and allocates attentional resources
Necessary for emotional balance, adaptation to environmental demands (including fearful situations, etc.), for creating meaningful connections with others (e.g. ability to interpret facial expressions and respond appropriately), and more…

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Reticular formation

Runs through central core of medulla, pons and midbrain
Reticular activating
system (RAS):

Reticular formation Runs through central core of medulla, pons and midbrain Reticular

keeps the cerebral
cortex alert and
conscious
Some motor control

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Brain protection 1.Meninges 2. Cerebrospinal fluid 3. Blood brain barrier

Brain protection 1.Meninges 2. Cerebrospinal fluid 3. Blood brain barrier

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Meninges

Dura mater: 2 layers of fibrous connective tissue, fused except for dural

Meninges Dura mater: 2 layers of fibrous connective tissue, fused except for
sinuses
Periosteal layer attached to bone
Meningeal layer - proper brain covering
Arachnoid mater
Pia mater
Note superior
sagittal sinus

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Dura mater - dural partitions Subdivide cranial cavity & limit movement of brain

Falx

Dura mater - dural partitions Subdivide cranial cavity & limit movement of
cerebri
In longitudinal fissure; attaches to crista galli of ethmoid bone
Falx cerebelli
Runs vertically along vermis of cerebellum
Tentorium cerebelli
Sheet in transverse fissure between cerebrum & cerebellum

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Arachnoid mater
Between dura and arachnoid: subdural space
Dura and arachnoid cover brain loosely
Deep

Arachnoid mater Between dura and arachnoid: subdural space Dura and arachnoid cover
to arachnoid is subarachnoid space
Filled with CSF
Lots of vessels run through (susceptible to tearing)
Superiorly, forms arachnoid villi: CSF valves
Allow draining into dural blood sinuses
Pia mater
Delicate, clings to brain following convolutions

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Cerebrospinal Fluid CSF

Made in choroid plexuses (roofs of ventricles)
Filtration of plasma from capillaries

Cerebrospinal Fluid CSF Made in choroid plexuses (roofs of ventricles) Filtration of
through ependymal cells (electrolytes, glucose)
500 ml/d; total volume 100-160 ml (1/2 c)
Cushions and nourishes brain
Assayed in diagnosing meningitis, bleeds, MS
Hydrocephalus: excessive accumulation

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CSF circulation: through ventricles, median and lateral apertures, subarachnoid space, arachnoid villi,

CSF circulation: through ventricles, median and lateral apertures, subarachnoid space, arachnoid villi,
and into the blood of the superior sagittal sinus

CSF:
-Made in choroid plexus
-Drained through arachnoid villus

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Hydrocephalus

Hydrocephalus

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Blood-Brain Barrier

Tight junctions between endothelial cells of brain capillaries, instead of the

Blood-Brain Barrier Tight junctions between endothelial cells of brain capillaries, instead of
usual permeability
Highly selective transport mechanisms
Allows nutrients, O2, CO2
Not a barrier against uncharged and lipid soluble molecules; allows alcohol, nicotine, and some drugs including anesthetics

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White matter of the spinal cord

Ascending pathways: sensory information by multi-neuron chains

White matter of the spinal cord Ascending pathways: sensory information by multi-neuron
from body up to more rostral regions of CNS
Dorsal column
Spinothalamic tracts
Spinocerebellar tracts
Descending pathways: motor instructions from brain to more caudal regions of the CNS
Pyramidal (corticospinal) most important to know
All others (“extrapyramidal”)
Commissural fibers: crossing from one side of cord to the other
Most pathways cross (or decussate) at some point
Most synapse two or three times along the way, e.g. in brain stem, thalamus or other

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Major fiber tracts in white matter of spinal cord

Damage: to motor areas

Major fiber tracts in white matter of spinal cord Damage: to motor
– paralysis
to sensory areas - paresthesias

sensory

motor

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Major ascending pathways for the somatic senses

Spinocerebellar: proprioception from skeletal muscles to

Major ascending pathways for the somatic senses Spinocerebellar: proprioception from skeletal muscles
cerebellum of same side (don’t cross)
Dorsal column: discriminative touch sensation through thalamus to somatosensory cortex (cross in medulla)
Spinothalamic: carries nondiscriminate sensations (pain, temp, pressure) through the thalamus to the primary somatosensory cortex (cross in spinal cord before ascending)

(thousands of nerve fibers in each)

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Some Descending Pathways

Pyramidal tracts:
Lateral corticospinal – cross in pyramids of medulla;

Some Descending Pathways Pyramidal tracts: Lateral corticospinal – cross in pyramids of
voluntary motor to limb muscles
Ventral (anterior) corticospinal – cross at spinal cord; voluntary to axial muscles
“Extrapyramidal” tracts: one example

Synapse with ventral (anterior) horn interneurons

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Check out: Medical gross anatomy atlas images (good teaching pics):
http://anatomy.med.umich.edu/atlas/atlas_index.html
(can access from

Check out: Medical gross anatomy atlas images (good teaching pics): http://anatomy.med.umich.edu/atlas/atlas_index.html (can
Paul Wissman’s site also:
-anatomy and physiology
-brain and spinal cord
-brain pics at U. Mich)
Really good site for photos of human brain dissections:
http://library.med.utah.edu/WebPath/HISTHTML/NEURANAT/NEURANCA.html

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Hints & additional pics

Unless your prints of the slides are very large

Hints & additional pics Unless your prints of the slides are very
and clear, look at the pictures from the book on your computer screen or in the book itself so you can read all the labels
Anything in bold, italicized or repeated should be learned
Remembering the terminology from the quiz will help you figure things out
Anterior horn cells = ventral motor neurons
Forget funiculi; know dorsal column (spinal cord)

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Know the names of the ventricles and which ones connect to which,

Know the names of the ventricles and which ones connect to which,
in order
You don’t need to know the #s of the Brodman areas
You do need to know where are the: primary somatosensory, primary motor, broca’s speech, visual cortex, the lobes of the brain, main sulci and fissures, precentral and postcentral gyri and which go with which of motor and sensory, etc
For the most part, the medical info is FYI

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From this site, which also has text explanations:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.html

From this site, which also has text explanations: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.html

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Brain, sagittal sec, medial view

Cerebral hemisphere
Corpus callosum
Thalamus
Midbrain
Pons
Cerebellum

Brain, sagittal sec, medial view Cerebral hemisphere Corpus callosum Thalamus Midbrain Pons Cerebellum Medulla oblongata

Medulla oblongata

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Internal capsule

Anterior limb of internal capsule
Genu of internal capsule
Posterior limb

Internal capsule Anterior limb of internal capsule Genu of internal capsule Posterior limb of internal capsule
of internal capsule

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Pons & cerebellum, sagittal section, medial view

Midbrain
Cerebellum
Pons
Medulla oblongata
Inferior

Pons & cerebellum, sagittal section, medial view Midbrain Cerebellum Pons Medulla oblongata
colliculus
Superior medullary velum
Fourth ventricle

You don’t need to know #s 5 & 6)

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