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The Brain and Cranial Nerves
Melissa Gonzales McNeal 1
The Brain and Cranial Nerves1
Lecture Overview
• Brain
– Function
– Organization
– Protection and support
– Brain Regions - Anatomy
– Brain regions - Physiology
• Location
• Associated structures
• functions
– Limbic system
• Cranial Nerves2
Brain Spinal Cord
Central
Nervous System
Affterent Nerves Efferent Nerves
Cranial Nerves
Affterent Nerves Efferent Nerves
Spinal Nerves
StructuralClassification
Affterent Nerves
general senses
Efferent Nerves
skeletal muscle
Somatic
Nervous System
Affterent Nerves
visceral
SympatheticDivision
ParasympatheticDivision
Efferent Nerves
smooth muscle
cardiac muscle
glands
Autonomic
Nervous System
Functional Classification
Peripheral
Nervous System
NERVOUS SYSTEM
3
Functions of Brain
• Integration center
– Registers sensations
– Correlates sensations with one another and with stored information
– Makes decisions
– Initiates taking action
• Center for intellect, emotions, behavior, memory
• Directs behavior towards others4
The Brain and Cranial Nerves
Melissa Gonzales McNeal 2
An Introduction to the
Organization of the Brain
5 6
7
Protection and Support
of the Brain
8
The Brain and Cranial Nerves
Melissa Gonzales McNeal 3
Protection of Brain
• Cranial bones
• Cranial meninges
– Dura mater
• Periosteal layer
– Dural sinuses
» Superior sagittal sinus
• Meningeal layer
– Subdural space
– Arachnoid mater
– Subarachnoid space• Arachnoid villi (arachnoid granulations)
– Pia mater 9 10
A
B
CDE pink line
FG
H
I purple
space
Can you identify the
structures / regions (A-I)?
11 12
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13Dura Mater
14
Pia Mater 15
Fluid and ventricles
• Ventricles
– Lateral ventricles
• Septum pellucidum
• Interventricular foramen (foramen of monroe)
– Third ventricle
• Cerebral aqueduct
– Fourth ventricle
• Lateral and median apertures
– Choroid plexus
16
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Ventricles of the Brain
17 18
19 20
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• Can you trace a drop of CSF from the right
ventricle to the superior sagittal sinus?
– Be sure to list all structures it passes through
21
Cerebrospinal Fluid
• Protection: cushions neural structures
• Buoyancy: supports the brain
• Chemical stability: transports
– Nutrients
– Chemical messengers
– Waste products
22
Cerebrospinal
Fluid
23
You produce ~500 ml/day.
The total volume of CSF is
replaced about every 8
hours.
• Jack has stenosis of the left interventricular
foramen….
– Where would there be fluid and pressure build
up?
24
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Melissa Gonzales McNeal 7
Hydrocephalus25
26
Lots of blood vessels…
• Brain is about 2% of
your total body
weight.
• It utilizes ~20% of
ALL oxygen inhaled.
• Remember O2 is
used to make ATP.
27
The brain is the most metabolically
active organ in the body
Blood Brain
Barrier
Areas where the blood
brain barrier is not
intact:
• Portions of
hypothalamus
• Posterior pituitary
gland
• Pineal gland
• Choroid plexus
Brain vulnerable to
infection
Ex: HIV28
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Brain Regions
ANATOMY
29
Major Brain Regions
• Brain Stem
– Medulla oblongata
– Pons
– Midbrain
• Cerebellum
• Diencephalon
– Thalamus
– Hypothalamus
– Epithalamus
• Cerebrum 30
31 32
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33
Brain Stem
• Medulla oblongata
• Pons
• Midbrain
– Superior colliculi
– Inferior colliculi
– Red nucleus
– Substantia nigra
34
35 36
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37
Cerebellum
• Cerebellar hemispheres
• Arbor vitae
• Cerebellar cortex
38
39 40
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Melissa Gonzales McNeal 11
41
Diencephalon
• Thalamus
• Hypothalamus
– Pituitary gland
– Mammillary bodies
– Optic chiasm
• Epithalamus
– Pineal gland (body)
42
43 44
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45 46
47
Cerebrum
• Left and right cerebral hemispheres
– Cerebral cortex
– White matter
• Mostly myelinated axons
– Association tracts: same hemisphere
– Commissures: between hemispheres
– Projection tracts: ascending and descending
• Corpus callosum
– Nuclei
• Basal ganglia
48
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49 50
51 52
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53
Cerebrum
• Lobes
– Frontal lobe
– Parietal lobe
– Occipital lobe
– Temporal lobe
• Hippocampus
• Folds and grooves
– Precentral gyrus
– Postcentral gyrus
– Central sulcus
– Lateral sulcus
– Logitudinal fissure
– Transverse fissure 54
55 56
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57 58
Brain Regions
PHYSIOLOGY (FUNCTION)
59
Brain Stem
60
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THE MEDULLA OBLONGATA61
Medulla -
“vital signs”
• Cardiac center
• Vasomotor centers
• Respiratory centers
• Reflex centers (cough, sneeze, swallow, vomit)
• Sensory and motor nuclei for cranial nerves
(VIII, IX, X, XI, XII)
• Relay stations along sensory and motor
pathways
62
63
THE PONS
Pons
• Respiratory centers
• Sensory and motor nuclei for cranial nerves (V, VI, VII, VIII)
• Relay information to and from cerebellum64
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THE MIDBRAIN65
Midbrain (Mesencephalon)
66
The Midbrain (Mesencephalon)
• Superior colliculi: receives visual input
– Visual reflex movement
• Inferior colliculi: receives auditory data
– Auditory reflex movement
• Red nucleus
– Righting reflexes
• Nuclei for cranial nerves (III and IV)
• Substantia nigra…
67
Substantia Nigra
• Movement and balance
• Cells produce dopamine
– Acts on other neurons to control/regulate their firing.
• Parkinson’s Disease
68A B
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BRAINSTEM
RETICULAR FORMATION
69
Reticular Formation
• Network of gray matter in brainstem
– Ascending (RAS) and descending components
• ~ 25 specific behaviors
– Somatic motor control
• Adjust muscle tension for muscle tone, balance, and posture
• Central pattern generators
– breathing, chewing, swallowing
– Pain modulation (neuropeptides)
– Cardiovascular control
– Sleep and consciousness– Sleep, alertness, fatigue, motivation
– Habituation
• Attention, focus70
Reticular Formation
• Possibly involved with
– Introversion versus extroversion
– Chronic fatigue syndrome
– ADHD (attention deficit hyperactive disorder)
• Oldest portion of brain
71THE CEREBELLUM
Extensive dendrites of each
neuron receive input from up to
200,000 synapses
72
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The Cerebellum• Adjusts postural muscles of body
– Uses information provided by receptors in inner ear
• Programming and fine-tuning movements
controlled at conscious and subconscious levels– Trajectory and end
point
– What muscles should
be doing vs what
they are doing
– Sends corrective
feedback via
thalamus
• Alcohol impairs 73THE DIENCEPHALON
74
Hypothalamus
• Part of limbic system: involves emotional response
– Somatic motor patterns associated with rage, pleasure, pain, sexual arousal
• Behavioral drives: hunger, food intake, thirst
• Controls autonomic function
• Coordination of nervous and endocrine systems
• Secretion of hormones
– Oxytocin, antidiuretic hormone (ADH), plus others that control the pituitary gland
• Regulation of body temperature
• Controls circadian rhythms
• Memory75 76
Thalamus• Suppresses “unimportant
conscious sensation
• Integrates sensation
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THE CEREBRUM77
The corpus callosum
contains about 200 million
neuron fibers
Corpus Callosum
• Band of nerve fibers
that connect the
right and left
hemispheres
• Corpus Callosotomy
– “split-brain surgery”
78DIFFUSE AXONAL INJURY
Due to Motor Vehicle Accident
Basal Nuclei (Ganglia)
• Subconscious aspects of
voluntary movement
− Ex: shoulder position
and arm stabilization
when writing
• Huntington’s Chorea
•Caudate nucleus
•Putamen
•Globus pallidus
•Amygdala
•Substantia nigra
79
Hippocampus
A memory forming
center in the
temporal lobe80
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81
Functional
areas of
cerebral cortex
– Motor areas• Primary motor cortex
• Broca’s speech area - left hemisphere
– Sensory areas• Primary somatosensory cortex
• Primary auditory cortex
• Primary gustatory cortex
• Primary olfactory cortex
• Primary visual cortex
– Association areas• Premotor cortex (motor association area)
• Somatosensory association area
• Somatosensory visual areas (visual association area)
• Somatosensory auditory areas (auditory association area)
– Integrative centers
• Wernicke’s area - left hemisphere
• Prefrontal cortex
• Frontal eye field 82
Ex: musician
Ex: biceps brachii Ex: pain in thumb
Ex: paper cut, pocket
83
Ex: red and green
Ex: rose or stop light
84
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Broca’s
Wernicke’s
Language comprehensionThought the precedes speech
Damage
- sit on chair – unable to follow the command
- Unable to produce meaningful sentences
Ex: reading, sports
Cannot physically form wordsAphasia – still able to understand written/spoken work
IntellectComplex learning
Recall
Temporal relationships
Personality
Judgment
Consequences
85
???1. Prim older woman stripping in public
2. Tiger Woods (professional golfer)
3. Translator who speaks English, French, and
Japanese
4. Congenitally blind person reading Braille
5. Concert pianist who was in a car accident. She
can still physically play the piano but cannot
remember how.
A. Which Functional Region(s) are involved?
B. Well developed or damaged (disease or trauma)?86
87 88
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89 90
A
B
C DH
EF
G
I
J
K
Identify the
functional
areas: A-K
91
Phineas Gage
1848 92
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???
Primary motor cortex
Premotor cortex
Basal ganglia
Cerebellum
Reticular formation
• What specific brain regions are involved in
walking?
93
Higher Order Functions
• Cerebral cortex involved
• Involve both conscious and subconscious
information processing
• Subject to modification and adjustment over
time
94
LIMBIC SYSTEM
95
Limbic System
• Emotional brain
– Motor responses to emotion
– Control and expression of emotions
– Important roles in personality
• Facilitates memory storage and retrieval
• Associations with reward/pleasure and
punishment/aversion
96
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Limbic System
• Major structures
– Prefrontal cortex
– Hippocampus
– Thalamus
– Hypothalamus
• Mammillary bodies
– Amygdala
– Basal nuclei
97
MEMORY
Information from
• Ch 12 pgs 471-473
• Ch 14
98
Memory
• Memories: stored bits of information gathered
through experience
– Memory trace (engram): pathway in brain where
new synapses were formed or modified
• Synaptic plasticity: ability of synapses to
change
• Types
– Fact (declarative) memory: specific bit of
information
– Skill (procedural) memory: learned motor behavior99
Memory• Classes
– Immediate memory
• A few seconds
• Based on reverberating circuits
– Short term (primary) memories / working memory
• Seconds to hours
• Reverberating circuits or facilitated synapses
• Limited amount of information can be stored
– Long term memories
• Secondary memories: fade with time
• Tertiary memories: remain for a lifetime
• Memory consolidation: conversion from short term to
long term memory
– Hippocampus 100
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101 102
When I study matters?!?
Memory
Formation and storage
• Increased neurotransmitter release
• Facilitation at synapses
– Potentiation
– build up of ca2+ in synaptic end bulb causes
larger burst of neurotransmitter release
• Formation of additional synaptic
connections or neurotransmitter receptors103
???
• Symptoms include
– Short term
memory loss
– Changes in
personality
• What brain
regions are
affected and why?104
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CONSCIOUSNESS AND SLEEP
Dreaming permits each of and every one of us to be quietly
and safely insane every night of our lives
--William C. Dement
105
States of Consciousness• Conscious: awareness of and attention to
external stimuli
• Unconscious
– Sleep
• Deep sleep: cerebral cortex activity minimum
• Rapid eye movement (REM): dreaming, less receptive than deep sleep
– Coma
• Arousal: awaking from sleep
– Reticular activating system
• Alertness
• focus 106
Brain Waves
• Beta waves
– Mental activity and sensory stimulation
• Alpha waves
– Awake and resting with eyes closed
• Theta waves
– Children
– Drowsy or sleeping adults
• Delta (slow) waves
– Infants
– Deep sleep in adults 107
Sleep
• 4 stages of non-REM sleep
– Stage 1: relaxation, light sleep, alpha waves
– Stage 2: brain waves slow down
– Stage 3: theta and delta waves appear, vital
signs fall
– Stage 4: deep sleep
• Delta waves
• Decreased metabolism, decreased temperature
• Restorative sleep
• Difficult to wake108
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Sleep
• REM (rapid eye movement)
– Increased HR, BP, O2 consumption
– Brain activity begins in pons and midbrain
• Turns off motor neurons (temporary paralysis)
• Strongly activate inhibitory center in medulla
• Deepest stage (hardest to awaken)
– Thalamus
– Cerebral cortex
– Reticular formation
• Dreaming occurs in stage 4 and REM109
Cranial Nerves
110
Brain Spinal Cord
Central
Nervous System
Affterent Nerves Efferent Nerves
Cranial Nerves
Affterent Nerves Efferent Nerves
Spinal Nerves
Structural
Classification
Affterent Nerves
general senses
Efferent Nerves
skeletal muscle
Somatic
Nervous System
Affterent Nerves
visceral
Sympathetic
Division
Parasympathetic
Division
Efferent Nerves
smooth muscle
cardiac muscle
glands
Autonomic
Nervous System
Functional Classification
Peripheral
Nervous System
NERVOUS SYSTEM
111
Cranial Nerves
12 pairs – for each you need to know
Name and number
Sensory*, motor*, mixed (both)
General function
112* Predominately sensory or motor
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Olfactory Nerve I
• Sensory
• Smell
113
Optic Nerve II
• Sensory
• Vision
114
Oculomotor Nerve III
• Motor
• Moves eyeball
• Raises upper lid
• Constricts pupil
115
Trochlear Nerve IV
• Motor
• Moves eyeball
116
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Trigeminal Nerve V
• Mixed
• Sensory information
• Face, scalp, teeth
• Motor instructions
• Mastication
117
Abducent Nerve VI
Abducens
• Motor
• Moves eyeball
118
Facial Nerve VII
• Mixed
• Sensory information• Face• Taste
• Motor instructions• Scalp and face• Lacrimal glands• Salivary glands• Glands nose and
throat119
Vestibulocochlear Nerve VIII
Acoustic, Auditory, Stato-acoustic
• Sensory
• Vestibular• Balance• Orientation and head movement
• Cochlear• Hearing
120
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Glossopharyngeal Nerve IX
• Mixed
• Sensory information• Blood pressure • Dissolved gases
• Motor instructions• Salivary glands• Swallowing
121
Vagus Nerve X
• Mixed
• Larynx• Esophagus • Bronchial tubes• Heart• Stomach• Intestines• Pancreas
122
Accessory Nerve XI
• Motor
• Muscles of neck and upper back
• Speech 123
Hypoglossal Nerve XII
• Motor
• Movement of tongue
124
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Memory Devices
• Cranial nerve names
– Old Opie occasionally tries trigonometry and
feels very gloomy vague and hypoactive
– on occasion our trusty truck act funny, very
good vehicle any how
• Cranial nerve functions
– Some say marry money but my brother says big
brains matter more
125
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