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Central Nervous
System
Basic
Setup of the Nervous
System
Nervous Tissue
Peripheral Nervous
System
Spinal and Cranial
Nerves
Central Nervous
System: Integration
and Command
Brain
Spinal Cord
Sensory
Sensory
Skin, skeletal
muscle and joints
Motor
Visceral
Visceral Organs
Somatic:
Control of skeletal
muscles
Autonomic:
Regulates smooth
muscle, cardiac
muscle and glands
Sympathetic:
Fight or Flight
Parasympathetic
Rest and Digest
Basic
Setup of the
Nervous System
Nervous Tissue
Central Nervous
System: Integration
and Command
Brain
Spinal Cord
The Brain
• The brain is divided into 5
main areas based
originally on development
but also on function.
The Brain
• The brain is divided into 5
main areas based
originally on development
but also on function.
Forebrain
Midbrain
Hindbrain
Development
Starting with the Ventricles
• There are four
ventricles:
– The paired Cshaped lateral
ventricles
– The third ventricle
found in the
diencephalon
– The fourth
ventricle found in
the hindbrain
dorsal to the pons
Ventricles of the Brain: Another
View
Cerebral Hemispheres
• Form the superior part of
the brain and make up 83%
of its mass
• Contain ridges (gyri) and shallow grooves
(sulci)
• Contain deep grooves called fissures
• Are separated by the longitudinal fissure
longitudinal fissure
Gyri
sulci
fissures
Major Lobes, Gyri, and Sulci of
the Cerebral Hemisphere
• Deep sulci divide
the hemispheres
into five lobes:
– Frontal
– Parietal
– Temporal
– Occipital
– Insula
The Insula is deep
under temporal
lobe
The Insula
Major Lobes, Gyri, and Sulci of
the Cerebral Hemisphere
• Parieto-occipital
sulcus – separates
the parietal and
occipital lobes
• Lateral sulcus –
separates the
parietal and
temporal lobes
• The precentral and
postcentral gyri
border the central
sulcus
Cerebral Hemispheres
• The cerebral hemispheres have three
basic regions: cortex, white matter, and
basal nuclei
Midbrain
Cerebral Cortex
• The cortex – superficial
gray matter; accounts
for 40% of the mass of
the brain
• It enables sensation,
communication,
memory,
understanding, and
voluntary movements
Cerebral Cortex
• Each hemisphere acts
contralaterally (controls the
opposite side of the body)
• Hemispheres are not equal
in function
• No functional area acts
alone; conscious behavior
involves the entire cortex
This is not a political statement .
Functional Areas of
the Cerebral Cortex
• The three types of
functional areas are:
– Sensory areas – conscious
awareness of sensation
– Association areas –
integrate diverse
information (swat, just ate
or whatever it takes, I love
chicken)
– Motor areas – control
voluntary movement
Functional Areas of the
Cerebral Cortex
Motor
Association
Sensory
Functional Areas of the
Cerebral Cortex
Motor
Association
Sensory
Functional Areas of the
Cerebral Cortex
Motor
Association
Sensory
PET scans
Functional MRI
• Finger
pressing a
button.
• Which
finger?
• Free will
discussion
Cerebral Cortex: Motor Areas
•
•
•
•
Primary (somatic) motor cortex
Premotor cortex
Broca’s area
Frontal eye field
Primary Motor
Cortex
• Located in the precentral
gyrus
• Composed of pyramidal cells
whose axons make up the
corticospinal tracts
• Allows conscious control of
precise, skilled, voluntary
movements
• Actually signals muscles
Primary
Motor Cortex
• Motor homunculus
– A caricature of
location and
relative amounts of
cortical tissue
devoted to each
motor function
– When you use
scissors, you move
your jaw.
Premotor Cortex
• Located anterior to the
precentral gyrus
• Controls learned,
repetitious, or patterned
motor skills
• Involved in the planning of movements
Broca’s Area
• Broca’s area
– Located anterior to the
inferior region of the premotor area
– Present in one hemisphere (usually the left)
– A motor speech area that directs muscles of
the tongue
– Is active as one prepares to speak
– A logical forward expansion of the
area of the motor homonculus for
mouth muscles.
Frontal Eye
Field
• Frontal eye field
– Located anterior to the
premotor cortex and
superior to Broca’s area
– Controls voluntary eye movement
– Another logical expansion of the area of the
motor homunculus that controls the hand.
This increases hand-eye coordination.
Sensory Areas
• Primary somatosensory
cortex
• Somatosensory
association cortex
• Visual and auditory
areas
• Olfactory, gustatory,
and vestibular cortices
Sensory Areas
Primary
Somatosensory
Cortex
• Located in the postcentral
gyrus:
– Receives information from the skin and
skeletal muscles
– Exhibits spatial discrimination
• Somatosensory homunculus – caricature
of relative amounts of cortical tissue
devoted to each sensory function
Primary
Somatosensory
Cortex
• Somatosensory
homunculus –
caricature of
location and
relative amounts
of cortical tissue
devoted to each
sensory function
Somatosensory
Association
Cortex
• Located posterior to the
primary somatosensory
cortex
• Integrates sensory information
• Forms comprehensive understanding of
the stimulus
• Determines size, texture, and relationship
of parts
An example: The secondary sensory
association area determines “what just hit
me in the face?”
Visual Areas
• Primary visual
(striate) cortex
– Simple interpretations
(lines)
– Most of it is buried in the calcarine sulcus
– Receives visual information from the retinas
• Visual association area
– Surrounds the primary visual cortex
– Interprets visual stimuli (e.g., color, form, and
movement)
Striate Cortex
Auditory Areas
• Primary auditory cortex
– Located at the superior
edge of the temporal lobe
– Interprets pitch, rhythm,
and loudness
• Auditory association area
– Located posterior to the primary
auditory cortex
– Stores memories of sounds and
permits perception of sounds
– Let’s music affect mood and cause you to dance.
Association
Areas
• Prefrontal cortex
• Language areas
– Widely distributed
• General (common) interpretation area
• Visceral association area
Prefrontal Cortex
• Involved with intellect,
cognition, recall, and
personality
• Responsible for planning, complex ideas,
behaviors, concentration and the ability to
focus. This area is also responsible for
emotional traits, judgment and inhibition.
• Closely linked to the limbic system
(emotional part of the brain)
Prefrontal Cortex: Phineas Gage
Language Areas
• Major parts and functions:
– Wernicke’s area – involved
in sounding out unfamiliar
words
– Broca’s area – speech preparation and
production
– Lateral prefrontal cortex – language
comprehension and word analysis
– Lateral and ventral temporal lobe – coordinate
auditory and visual aspects of language
Language Areas
• Language is highly
distributed.
• There are many parts
to language.
– articulation, fluency,
names,
comprehension,
reading, writing
– Others
• Patients may lose
parts of their language
abilities.
General (Common)
Interpretation Area
• Ill-defined region including
parts of the temporal,
parietal, and occipital lobes
• Found in one hemisphere, usually the left
• Integrates incoming signals into a single thought
– Like right now, your GIA is saying “man, this lecture is
soooo cool.”
• Involved in processing spatial relationships
– Of outside world, one’s body, and even sentence
structure.
Visceral Association
Area
• Located in the cortex
of the insula
• Involved in conscious
perception of visceral
sensations
Lateralization
• Lateralization – each
hemisphere has
abilities not shared
with its partner
• Left hemisphere –
controls language,
math, and logic
• Right hemisphere –
controls visual-spatial
skills, emotion, and
artistic skills
Cerebral White Matter
• Consists of deep myelinated fibers and
their tracts
• It is responsible for
communication
between:
– The cerebral cortex,
the lower CNS
center, and areas of
the cerebrum
Cerebral White
Matter
• Types include:
– Association fibers –
connect different parts of
the same hemisphere
– Commissures – connect
corresponding gray areas
of the two hemispheres
– Projection fibers – enter
the hemispheres from
lower brain or cord
centers
Basal Ganglia
Midbrain
Basal Nuclei
Midbrain
• Masses of gray matter
found deep within the
cortical white matter
• Composed of several
different groups of cells; caudate,
putamen, nucleus accumbens, globus
pallidus, substantia nigra, subthalamic
nucleus, and historically the claustrum and
the amygdala.
• The function is generally motor.
Basal Nuclei
Basal Nuclei
Basal Ganglia
• The BG is the
master of the
motor system.
• It coordinates
many different
motor area from
brainstem to
cortex, to
cerebellum.
Basal Ganglia: Brake Hypothesis
• The function of the basal ganglia is often
described in terms of a "brake hypothesis".
– To sit still, you must put the brakes on all movements
except those reflexes that maintain an upright
posture.
– To move, you must apply a brake to some postural
reflexes, and release the brake on voluntary
movement.
• Deficits in the BG tend to fall into one of two
categories:
– the presence of extraneous unwanted movements
– an absence or difficulty with intended movements.
Huntington’s
Basal Ganglia
Hemiballismus
Parkinson’s
Hemiballismus
Parkinson’s Disease
Huntington’s Chorea
Hit Dunn
Seconday
motor:
coordinates
muscles of
the arm
Primary
motor: moves
individual
muscles
Basal Ganglia:
Starts and Stops
Also “manages”
All the other inputs.
Amygdala: What is
my emotional intent
(good job, joking,
anger
Cerebellum:
Has
“instructions”
on how to
throw a
punch.
Many parts of the brain would
contribute to the decision to hit Dunn.
The Basal Ganglia will coordinate
these inputs.
The
Diencephalon
Forebrain
Midbrain
Hindbrain
Diencephalon
• Central core of the
forebrain
• Consists of three
paired structures –
– Thalamus
– Hypothalamus
– Epithalamus
Thalamus
• Paired, egg-shaped masses
that connected at the midline by the
intermediate mass
• Contains four groups of nuclei – anterior,
ventral, dorsal, and posterior
• Can be thought of as Grand Central
Station for sensory information.
Thalamus
limbic
language
emotion
auditory
vision
Integrates
thalamic
motor
Coordinates
BG with
somatosensory
Thalamic Function
• Afferent impulses from all senses (except
olfaction) converge and synapse in the
thalamus
• Impulses are sorted out, edited, and
relayed as a group
• Some motor information
• Plays a key role in mediating
sensation, motor activities,
cortical arousal, learning, and
memory
Thalamic Function
• Hearing your name in a crowd
• Picking out what sensory information is
important (the tv when there is a lot of
bacground noise)
• Autism
Hypothalamus
• Hypothalamic Nuclei
• Mammillary bodies
– Small, paired nuclei bulging
anteriorly from the
hypothalamus
– Relay station for olfactory
pathways
• Infundibulum – stalk of the
hypothalamus; connects to the
pituitary gland
– Main visceral control center
of the body
Hypothalamus
• Hypothalamic
Nuclei
• Mammillary
bodies
• Infundibulum
Hypothalamic Nuclei
Hypothalamic Nuclei
Lack of
hunger
Sleep
Obesity
Hypothalamic Function
• Regulates blood pressure, rate and
force of heartbeat, digestive tract
motility, rate and depth of breathing,
and many other visceral activities
• Is involved with perception of pleasure, fear, and
rage
• Controls mechanisms needed to maintain
normal body temperature
• Regulates feelings of hunger and satiety
• Regulates sleep and the sleep cycle
Endocrine Functions of the
Hypothalamus
• Releasing hormones control secretion of
hormones by the anterior pituitary
• The posterior pituitary releases ADH and
oxytocin
Epithalamus
• Pineal gland –
extends
from the posterior
border
and secretes
melatonin
– Melatonin – a
hormone involved
with sleep
regulation, sleepwake cycles, and
mood
• Choroid plexus – a
structure that
secretes cerebral
spinal fluid (CSF)
The Brainstem
Forebrain
Midbrain
Hindbrain
Brain Stem
• Consists of three
regions
– Midbrain
– Pons,
– Medulla oblongata
• Similar to spinal cord but contains
embedded nuclei
Brain Stem
• Controls automatic
behaviors necessary
for survival (respiration,
heart rate, etc.)
• Provides the pathway
for tracts between higher
and lower brain centers
• Associated with 10 of the 12 pairs of
cranial nerves
Brain Stem
Midbrain
• Located between the diencephalon
(thalamus) and the pons
• Midbrain structures include:
– Cerebral peduncles – two bulging structures
that contain descending pyramidal motor
tracts
– Cerebral aqueduct – hollow tube that
connects the third and fourth ventricles
– Various nuclei
Brain Stem
Midbrain Nuclei
• Corpora quadrigemina – four dome
like protrusions of the dorsal midbrain
• Superior colliculi – visual reflex centers
• Inferior colliculi – auditory reflex centers
• Substantia nigra – functionally linked to
basal nuclei (Parkinson’s)
• Red nucleus – largest nucleus of the
reticular formation; red nuclei are relay
nuclei for some descending motor pathways
Midbrain Nuclei: Colliculi
• Corpora quadrigemina –
four domelike protrusions of
the dorsal midbrain
• Superior colliculi – visual
reflex centers
• Inferior colliculi – auditory
reflex centers
Midbrain Nuclei
Pons
• Bulging brainstem region
between the midbrain and
the medulla oblongata
• Fibers of the pons:
– Connect higher brain centers and the spinal
cord
– Relay impulses between the motor cortex and
the cerebellum
• Location of the Reticular Formation
Medulla
Oblongata
• Most inferior part of
the brainstem
• Pyramids – two
longitudinal
ridges formed by
corticospinal
tracts
• Decussation of the
pyramids
– crossover points of the
corticospinal tracts
Medulla
Nuclei
• Inferior olivary nuclei –
gray matter that relays
sensory information
• Cranial nerves X, XI, and XII are associated with
the medulla
• Vestibular nuclear complex – synapses that
mediate and maintain equilibrium
• Ascending sensory tract nuclei, including
nucleus cuneatus and nucleus gracilis
Medulla Nuclei
• Cardiovascular control center – adjusts
force and rate of heart contraction
• Respiratory centers –
control rate and depth
of breathing