Instructor

1
BRAIN CRANIAL NERVES
Anatomy Physiology

• Instructor
• Terry Wiseth

2
Organization Of Nervous System
3
Principle Parts Of The Brain

• Adult brain
• 100 billionneurons
• 3 pounds
• 1) cerebrum
• 2) diencephalon
• 3) brain stem
• 4) cerebellum
• 5) cerebrospinal fluid and ventricles

4
Brain Stem

• Medulla oblongata
• Midbrain
• Pons

5
Diencephalon

• Thalamus
• Hypothalamus

6
Cerebrum

• Cerebral hemispheres
• Left and right sides

7
Cerebellum

• Second largest part of the brain
• shaped like a butterfly with cerebral hemispheres

8
Protection And Coverings

• skull
• cranial meninges
• continuous with the spinal meninges
• dura mater
• arachnoid
• pia mater

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Protection And Coverings

• skull
• cranial meninges
• continuous with the spinal meninges
• dura mater
• arachnoid
• pia mater

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Protection And Coverings

• skull
• cranial meninges
• continuous with the spinal meninges
• dura mater
• arachnoid
• pia mater

11
Cerebrospinal Fluid

• CSF
• circulates through
• subarachnoid space
• ventricles
• cavities in the brain

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Cerebrospinal Fluid

• Clear, colorless fluid
• Nourish, protect brain
• Glucose
• Proteins
• Lactic acid
• Urea
• Cations
• Anions
• Lymphocytes

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Cerebrospinal Fluid

• Functions
• 1) shock absorbing
• 2) chemical protection
• 3) circulation

14
Ventricles

• CSF filled cavities in brain
• Continuously circulates through the subarachnoid
  space and spinal cord and through cavities within
  the brain

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Ventricles

• CSF filled cavities in brain
• Continuously circulates through the subarachnoid
  space and spinal cord and through cavities within
  the brain

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Choroid Plexuses

• Networks of capillaries in walls of the
  ventricles
• Source of cerebrospinal fluid as it oozes from
  the capillaries
• Normally CSF is reabsorbed as rapidly as it is
  formed
• 480 ml/day

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CSF

• Absorption of the CSF into the blood stream
• takes place in the sagittal sinus through
  structures called arachnoid villi

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CSF

• When the CSF pressure is greater than the venous
  pressure
• CSF will flow into the blood stream

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CSF

• However, the arachnoid villi act as "one way
  valves
• if the CSF pressure is less than the venous
  pressure
• the arachnoid villi will NOT let blood fluid pass
  into the ventricular system

Venous High
CSF Low
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CSFCirculation
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Hydrocephalus

• Obstruction or inflammation in brain can
  interfere with drainage of CSF
• Ex. Tumor, congenital blockage
• Accumulating fluids raise CSF pressure causing
  bulging heads and compressed nerve tissue in
  brain
• Implant drain courses from the ventricle to
  subclavian veins which release pressure

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Hydrocephalus
23
Blood Supply

• Brain consumes 20 of the O2 volume while the
  body is at rest
• Amount of O2 utilized varies with the degree of
  mental activity
• 1-2 minute interruption in
  blood flow may impair brain
  cells
• Brain cells deprived of O2 for
  over 4 minutes are
  permanently
  damaged

24
Blood Supply

• Lysosomes present in brain cells are sensitive to
  decreased O2 concentration
• Lysosomes may break open releasing enzymes
  destroying the brain cell

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Brain Injuries

• Damage to brain can result from trauma due to
  impact and release of oxygen free radicals
  (charged O2) from damaged cells
• Free radicals causedamage by disruptingcellular
  DNA andenzymes
• Brain cells recoveringfrom stroke alsorelease
  free radicals

26
Blood Supply

• Carbohydrate storage is limited in brain cells
  thus supply of glucose must be continuous
• Glucose, O2, CO2, H2O, alcohol, caffeine,
  nicotine, heroin, anesthetics pass readily from
  bloodstream into brain cells

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Blood Supply

• Creatinine, urea, Na, K, Cl- enter brain cells
  much slower
• Proteins, antibodies do not pass at all from
  blood into brain cells

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Blood Brain Barrier

• BBB
• Capillary linings of blood vessels in the brain
• Less leaky than other body capillaries
• Astrocytes (neuroglia) able to select to some
  degree which substances pass from the blood into
  the brain cells
• Important to protect brain from harmful
  substances and pathogens

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Blood Brain Barrier

• Injury to brain can cause breakdown in BBB
• Small regions of brain in 3rd and 4th ventricle
  called circumventricular organs (CVOS) lack BBB
  and can monitor chemical changes in blood

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Yawn

• We yawn when nerves in the brain stem find
  there's too much carbon dioxide in the blood
• A yawn makes the muscles in our mouth and throat
  contract and forces our mouth wide open
• allowing us to expelcarbon dioxide andtake in a
  large amountof oxygen-rich air

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CVOS

• Hypothalamus, pineal gland, pituitary gland
• Able to coordinate activities of endocrine and
  nervous system
• Ex BP, fluid balance, hunger, thirst

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Brain Stem

• 1) midbrain
• 2) pons
• 3) medulla oblongata

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Brain Stem

• 1) midbrain
• 2) pons
• 3) medulla oblongata

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Medulla Oblongata

• Continuous with upper part of spinal cord
• Most tracts cross at the upper part of the spinal
  cord
• Tracts from left side lead to right side of the
  brain (sensory and motor)

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Medulla Oblongata

• Regions within the medulla
• 1) regulate rate and force of heartbeat
• 2) regulate diameter of blood vessels
• 3) regulate basic rhythm of breathing
• 4) coordinate swallowing, vomiting, coughing,
  sneezing, hiccuping

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Medulla Oblongata

• Associated with the medulla are regions which
  also control
• 1) efficiency of precise, voluntary movements
• 2) maintenance ofequilibrium and posture
• 3) cranial nerves VIII-XII
• Hard blows to back of heador neck can be fatal

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Pons

• Bridge connecting the spinal cord with the brain
• Bridge to connectleft and right sidesof the
  brain
• Cranial nerves V-VIII

38
Midbrain

• Reflex centers for movement of eyes, head, neck
  is response to visual and auditory stimuli
• Controls subconscious activities
• Convey information from lower brain centers to
  higher brain centers

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Midbrain

• Reflex centers for movement of eyes, head, neck
  is response to visual and auditory stimuli
• Controls subconscious activities
• Convey information from lower brain centers to
  higher brain centers

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Diencephalon
Thalamus Hypothalamus
Thalamus Hypothalamus
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Thalamus

• Principle relay station from sensory impulses
  that reach the cerebral cortex from the spinal
  cord, brain stem, cerebellum and other parts of
  the cerebrum

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Thalamus

• Crude sensations of pain, temperature, pressure
• Some voluntary motor actions, arousal, emotions,
  and memory are relayed through the thalamus

43
Hypothalamus

• Lacks a blood-brain barrier
• Major regulation of homeostasis
• Controls and integrates activities of the
  autonomic nervous system (ANS)

44
Hypothalamus

• Associated with emotions of rage and aggression
• Regulates
• Heart rate
• Peristalsis
• Glandular
  secretions
• Bladder control
• Bodytemperature

45
Hypothalamus

• Regulates food intake
• Hunger and satiety centers
• Regulates water intakeThirst center
• Rising osmotic pressuresensation of thirst
• Maintains waking state andsleep patterns

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Cerebrum

• Forms the bulk of the brain
• Cerebral cortex
• Limbic system

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Cerebrum

• Forms the bulk of the brain
• Cerebral cortex
• Limbic system

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Cerebral Cortex

• Surface of the cerebrum 2-4 mm thick
• Composed of gray matter
• Cerebral white matter lies beneath the cerebral
  cortex

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Cerebral Cortex

• Surface of the cerebrum 2-4 mm thick
• Composed of gray matter
• Cerebral white matter lies beneath the cerebral
  cortex

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Cerebral Cortex

• Surface of the cerebrum 2-4 mm thick
• Composed of gray matter
• Cerebral white matter lies beneath the cerebral
  cortex

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Cerebral Cortex

• Cerebrum partially divided longitudinally into
  left and right hemispheres
• Each cerebral hemispheres is further subdivided
  into four lobes
• Frontal
• Parietal
• Temporal
• Occipital

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Cerebral Cortex

• Cerebrum is seat of intelligence
• Ability to read, write, speak, calculate, compose
  music, memory, plan for the future, create

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Limbic System

• Emotional brain
• Ring of structures encircling the brain stem

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Limbic System

• Functions in emotional aspects of behavior
  related to survival
• May also have some functions in memory of strong
  emotions
• Associated with pleasure, pain, rage, anger,
  fear, sorrow, sexual feelings, docility and
  affections

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Functional Areas

• 1) sensory areas
• Receive and interpret sensory impulses
• 2) motor areas
• Control muscular movement
• 3) association areas
• Deal with complex integrative functions, memory,
  emotions, reasoning, will, judgement,
  personality, intelligence

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Functional Areas
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Sensory Areas

• Input flows mainly to posterior half of the
  hemispheres to primary sensory area
• Secondary sensory association areas are adjacent
  to primary area

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Secondary Sensory Areas

• Receive input from them interpreting sensory
  experiences into meaningful patterns of
  recognition and awareness
• Ex damage to primary visual area may lose part
  of their visual field
• Damage to visual association area may see
  normally yet be unable to recognize a friend

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Sensory Areas

• General sensory area
• Primary visual area
• Primary auditory area
• Primary gustatory area
• Primary olfactory area

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Sensory Areas
General sensory area
Primary visual area
Primary auditory area
Primary gustatory area
Primary olfactory area
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General Sensory Area

• 1,2,3
• Localizes exactly the points of the body where
  sensations originate
• Thalamus registers sensations in a general way

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Primary Visual Area

• 17
• Receives impulses from thalamus containing
  information concerning shape, color, and movement

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Primary Auditory Area

• 41,42
• Interprets basic characteristics of sound
  (pitch, rhythm)

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Primary Gustatory Area

• 43
• Receives impulses related to taste

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Primary Olfactory Area

• Medial aspect of temporal lobe
• Receives impulses related to smell

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Motor Areas

• Mainly anterior portion of each hemisphere
  generates outputs
• Primary motor area
• Language area

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Primary Motor Area

• 4
• Controls voluntary contractions of specific
  muscles

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Language Area

• 44
• Motor speech area
• Translation of thoughts into speech
• Coordinated contractions of speech and breathing
  muscles
• Translation of speech or written words into
  thought involves both sensory and association
  areas

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Association Areas

• Consist of association tracts that connect motor
  and sensory areas and peripheral parts of the
  cerebral cortex

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Association Areas
Somatosensory association area
Visual association area
Auditory association area
Gnostic area
Premotor area
Frontal eye field
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Somatosensory Association Area

• 5,7
• Integrates and interprets sensations
• Determines exact shape and texture of an object
  without looking at it
• Sense the relationship of inner body part to
  another
• Also stores memories of past sensory experiences

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Visual Association Area

• 18,19
• Receives sensory impulses from primary visual
  area and the thalamus
• Relates present to past visual experiences with
  recognition and evaluation of what is seen

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Auditory Association

• 22
• Determines a sound is speech, music or noise
• Interprets meaning of speech by translating words
  into thought

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Gnostic Area

• 5,7,39,40
• Common integrative area of somatosensory, visual,
  auditory, taste and smell areas
• Also receives impulses from thalamus and brain
  stem
• Integrates information from sensory association
  area so that a common thought can be formed

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Premotor Area

• 6
• Concerned with learned motor activities of
  complex and sequential nature
• Ex. Write a word
• Serves as a memory bank for learned skill
  movements

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Frontal Eye Field

• 8
• Controls involuntary scanning movements of the
  eyes
• Ex. Searching for a word in a dictionary

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Speech Area Injuries

• Language areas are located in the left cerebral
  hemispheres
• Aphasia
• Inability to speak
• Injury to sensory or motor speech areas

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Speech Area Injuries

• Nonfluent aphasia
• Damage only to motor speech area
• Inability to
  properly articulate
• Person knows what to say but cannot speak

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Speech Area Injuries

• Fluent aphasia
• Damage to gnostic or auditory association
• Faulty understanding of spoken or written words
• Producing fluently strings of words without
  meaning

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Speech Area Injuries

• Word deafness
• Inability to understand spoken words
• Word blindness
• Inability to understand written words

Hello How Are You
Hello How Are You
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EEG

• Electroencephalogram (EEG)
• Electrical impulses
• Generation of nerve impulses collectively called
  brain waves
• Record of brain waves called EEG

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Brain Waves

• Alpha waves
• Beta waves
• Theta waves
• Delta waves

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Brain Waves

• Alpha waves
• Present during wake and resting stages with eyes
  closed
• Beta waves
• Appear when nervous system is active
• Ex. Sensory input, mental activity

84
Brain Waves

• Theta waves
• Occur in individuals experiencing emotional
  stress
• May also occur in
  disorders of brain
• Delta waves
• Occur during deep sleep
• Normal in an awake infant
• Indicate brain damage in an awake adult

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EEG

• Used to diagnose
• Epilepsy
• Seizure disorders
• Tumors
• Infectious disease
• Trauma
• Hematoma
• Metabolic disorders
• Degenerative diseases
• Brain death

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Brain Lateralization

• Functional and anatomical differences between
  left and right hemispheres of the brain
• Ex. Left-handed people
• Parietal and occipital lobes of right hemisphere
  are narrower than corresponding lobes of left side

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Brain Lateralization

• Left hemisphere
• Controls right sideof body
• More important for
• Spoken
• Written
• Numerical andscientific skills
• Reasoning

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Brain Lateralization

• Right hemisphere
• Controls left side of
  body
• More important for
• Insight
• Imagination
• Musical and artistic
  awareness
• Space and pattern
  perception
• Generating mental images of sight, sound, touch,
  taste and smell to compare relationships

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Cerebellum

• Subconscious movements of skeletal muscles,
  equilibrium

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Cerebellum

• Functions to compare the intended movement
  determined by the motor areas with whatis
  actuallyhappening

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Cerebellum

• If intent of motor area is not attained the
  cerebellum detects the variation and sends
  signals to motor areas of brain to inhibit or
  stimulate activity of skeletal muscles

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Cerebellum

• Coordinates skilled movements
• Regulates posture, balance
• Ex. Dancing, catching a baseball

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Neurotransmitters

• Approximately 50 substances act as
  neurotransmitters in the brain
• Results of neurotransmitters can be excitation or
  inhibition of neurons
• Acetylcholine
• Biogenic amines
• Amino acids
• Neuropeptides

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Acetylcholine

• ACh
• May be excitatory or inhibitory
• ACh inactivated by acetylcholinesterase (AChe)
• Major center of ACh release are neurons which
  project through the cerebral cortex and limbic
  system
• Destruction of these neurons occurs in
  individuals suffering from Alzheimer's disease

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Amino Acids

• excitatory
• glutamate
• aspartate
• inhibitor
• gamma aminobutyric acid (GABA)
• valium enhances action of GABA

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Biogenic Amines

• can be either excitatory or inhibitory
• Norepinephrine
• epinephrine
• dopamine
• serotonin
• histamine

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Biogenic Amines

• Dopamine
• Involved in gross automatic movements of skeletal
  muscles
• Serotonin
• Thought to be involved in inducing sleep
• Control of mood

98
Neuropeptides

• Largest family of neurotransmitters
• May have either excitatory or inhibitory actions

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Neuropeptides
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Enkaphalins

• 1974 found that certain brain cells have
  receptors for opiate drugs
• Ex. Morphine, heroin
• Quest to find the naturally occurring substances
  that use these receptors brought to light the
  neuropeptides
• Enkaphalins
• Potent analgesic effects
• 200x stronger than morphine

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Opioids

• Other opioids include endorphins and dynorphins
• Opioids are the bodys natural pain-killers
• Have been linked to improve memory, learning,
  feelings of pleasure, (euphoria), sexual drive,
  depression, schizophrenia

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Opioids

• Analgesic effects of acupuncture may be due to
  increased release of enkaphalins or endorphins

103
Opioids

• If someone unexpectedly pricks oneself
• a message from the spinal cord is transmitted to
  the cortex of the cerebrum
• which results in the first experience of pain

104
Opioids

• In order to prevent putting there hand into the
  sewing box just as carelessly on a second
  occasion and to introduce a moment of learning
• stimuli are sent (slowly) from the spinal cord to
  the part of the brainstem where the opiate
  receptors are located

105
Opioids

• This area is responsible for the alarming or
  threatening aspect of pain
• this effect which is remedied so effectively by
  the administration of opiates
• The feeling itself does not disappear so much as
  lose its threatening character

106
Opioids

• It is this which lends the opiates their
  painkilling (analgesic) effect
• has virtually no effect whatever on the other
  sensory perceptions, consciousness or the motor
  functions

107
Opioids

• All other substances with a painkilling effect
• laughing gas
• alcohol
• ether
• barbiturates
• have a effect on consciousness, motor
  coordination, the intellect and emotional control

108
Neurotransmitters
109
Chocolate

• The chemical phenylethylamine
• causes a slightly dreamy feeling
• produced by the brain when two people fail in
  love
• Interesting enough,the same chemicalcan be
  found inchocolate

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Cranial Nerves

• 12 pair of cranial nerves which originate in the
  brain

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Cranial Nerves

• I) olfactory
• Smell
• II) optic
• Vision
• III) occulomotor
• Movement of eyelid
• movement of eyeball
• accommodation of lens pupil
  constriction

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Cranial Nerves

• IV) trochlear
• Movement of eyeball
• V) trigeminal
• Chewing mouth
• tongue touch,
  pain, temperature
• VI) abducens
• Movement of eyeball

113
Cranial Nerves

• VII) facial
• Facial expression secretions of saliva, tears
  taste (anterior 1/3 of tongue)
• VIII) vestibulocochlear
• Hearing, equilibrium
• IX) glossopharyngeal
• Secretion of saliva
• Taste (posterior 1/3 of tongue)

114
Cranial Nerves

• X) vagus
• Smooth muscle contraction and relaxation
• Secrete digestive juices
• Sensations from trachea, lungs, esophagus, heart,
  stomach, SI, LI, gall bladder

115
Cranial Nerves

• XI) accessory
• Swallowing head movement
• XII) hypoglossal
• Movement of tongue during speech, swallowing

116
Cranial Nerves
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Disorders Of The Brain

• Stroke
• Alzheimers disease
• Brain tumors
• Cerebral palsy
• Parkinsons disease
• Multiple sclerosis
• Headache
• Dyslexia
• Reyes syndrome

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Stroke

• Cerebrovascular accident (CVA)
• Most common brain disorder
• 1) ischemic- most common
• Decreased blood supply
• blood clots, plaque build-up
• 2) hemorrhagic- rupture of blood vessel

119
Stroke

• Transient ischemic attack (TIA)
• Temporary cerebral dysfunction caused by impaired
  blood flow to the brain
• TIA persists for a few minutes and last 24 hours
• Leaves no persistent neurological deficits

120
Stroke
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Alzheimers Disease

• Alzheimers disease (AD)
• Afflicts 11 of population over 65 years old
• Progressive neuronal loss with associated loss of
  neural functions
• Cause unknown
• Genetic ?
• Aluminum ?
• Virus ?

122
Brain Tumors

• Benign or malignant growth
• Pressures affecting normal tissues produce
  characteristic signs and symptoms
• Surgery
• Radiation therapy
• Chemotherapy

123
Brain Tumors
124
Cerebral Palsy

• Cerebral palsy (C)
• Group of motor disorders resulting in muscular
  incoordination and loss of muscle control

125
Cerebral Palsy

• Caused by brain damage to motor area of the brain
  during fetal life, birth or infancy
• Non-progressive disease

126
Parkinsons Disease

• Parkinsons Disease (PD)
• Progressive disorder of CNS to elderly
• Around 60 years old
• Toxic environmental factors suspected as cause
• Imbalance of neurotransmitters produce symptoms
  of PD

127
Parkinsons Disease

• Involuntary muscle contractions interfere with
  voluntary movement
• Treatment with dopamine (which is lacking in PD
  patient) does not work because dopamine will not
  cross the BBB
• Levodopa (l-dopa) treatment elevates brain levels
  of dopamine and lessons the symptoms
• Does not slow the disease
• Transplanting of fetal nerve tissue (dopamine
  rich) into patients have shown some degree of
  improvement

128
Multiple Sclerosis
Normal

• Multiple sclerosis (MS)
• Progressive destruction of myelin sheaths of
  neurons in the CNS
• Slows and short circuits conduction of nerve
  impulses
• Cause is unknown
• No treatment

Abnormal
129
Multiple Sclerosis

• Muscular weakness, visual impairment, vertigo are
  some of the symptoms
• Sufferers experience attacks with periods of
  remission lasting up to two years
• Viral infection has been implicated as a cause
• Initiates an autoimmune response in which T-cells
  destroy the myelin producing cells
• Immunosuppressive drugs are often given

130
Multiple Sclerosis
131
Dyslexia

• Impairment of brains ability to translate images
  into language
• Distorted ability to read, write, count
• Letters in words seem transposed, reversed or
  upside down
• Dog...........God or bog
• Oil...............710

132
Dyslexia

• 3X more common in males than females
• Left hemispheres more active than right
  hemisphere (language area)

133
Headache

• Causes may include
• Brain tumors
• Blood vessel abnormalities
• Inflammation
• Decrease in O2 supply to the brain
• Infections of sensory organs and sinuses

134
Headache

• Analgesic, tranquilizing compounds effective for
  tension headache but not migraine
• Migraine sufferers find some relief with
• Biofeedback
• Dietary changes
• Drugs which constrictblood vessels

135
Reyes Syndrome

• Reyes syndrome (RS)
• Seems to follow a viral infection
• Aspirins may be risk factor in the development of
  RS
• Brain damage result of cerebral swelling

136
Brain Quotes

• Aristotle taught that the brain exists merely to
  cool the blood and is not involved in the process
  of thinking

This is true only of certain persons
137
Brain Jokes
138
Brain Jokes
139
My girlfriend and I went on a picnic
I don't know how she did it, but she got poison
ivy on the brain
When it itched, the only way she could scratch
it was to think about sandpaper
Steven Wright
140
END BRAIN CRANIAL NERVES