Transcript Chapter 13: Peripheral Nervous System

I.
Overview
II.
Brain Stem
III. Cerebellum
IV. Diencephalon
V.
Brain
Cerebrum
VI. Cranial Nerves
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I.
Overview
A.Function
B.Protection
C.Blood Supply
D.Cerebrospinal Fluid
II.
Brain Stem
III.
Cerebellum
IV.
Diencephalon
V.
Cerebrum
VI.
Cranial Nerves
Brain
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The Brain and Cranial Nerves
1. Sensations
2. Memory
3. Emotions
4. Decision making
5. Behavior
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Principal Parts of the Brain
1. Cerebrum
Cerebrum
2. Diencephalon
a) Thalamus
b) Hypothalamus
3. Cerebellum
4. Brainstem
a) Medulla
Diencephalon
b) Pons
c) Midbrain
Brain Stem
Cerebellum
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Protective Coverings of the Brain

Bone


Periosteum
And Bone
Periosteum
Meninges same as around
the spinal cord
1. dura mater
2. arachnoid mater
3. pia mater
Dura Mater
Arachnoid Mater
Pia Mater
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Protective Coverings of the Brain
Falx cerebri

Dura mater extensions
1. falx cerebri
2. tentorium cerebelli
3. falx cerebelli
Tentorium
cerebelli
Falx cerebelli
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Ependymal
cells
Blood Supply to Brain
 Arterial blood supply is branches
from circle of Willis on base of
brain
Capillary
Fluid
O2
Elec.
 Vessels on surface of brain---penetrate tissue
Glucose
 Uses 20% of our bodies oxygen &
glucose needs
 blood flow to an area
increases with activity in that
area
 deprivation of O2 for 4 min
does permanent injury
 at that time, lysosome
release enzymes
waste
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Ependymal
cells
Blood Supply to Brain
 Blood-brain barrier (BBB)
Capillary
Fluid
O2
 protects cells from some
toxins and pathogens
Elec.
Glucose
 proteins & antibiotics
can not pass but
alcohol & anesthetics
do
 tight junctions seal
together epithelial cells,
continuous basement
membrane, astrocyte
processes covering
capillaries
waste
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Cerebrospinal Fluid (CSF)

80-150 ml (3-5oz)

Clear liquid containing glucose,
proteins, & ions

Functions
1. mechanical protection

floats brain & softens
impact with bony walls
2. chemical protection

optimal ionic
concentrations for action
potentials
3. circulation

nutrients and waste
products to and from
bloodstream
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Origin of CSF
Lateral
Ventricles
Choroid
plexus
 Choroid plexus =
capillaries covered by
ependymal cells
 2 lateral ventricles, one
within each cerebral
hemisphere
 roof of 3rd ventricle
 fourth ventricle
Third
Ventricles
Fourth
Ventricles
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Drainage of CSF from Ventricles
 One median aperture &
two lateral apertures
allow CSF to exit from the
interior of the brain
Lateral
aperture
Median
aperture
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I.
Overview
II.
Brain Stem
A.Medulla Oblongata
B.Pons
C.Midbrain
D.Reticular Formation
III.
Cerebellum
IV.
Diencephalon
V.
Cerebrum
VI.
Cranial Nerves
Brain
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Medulla Oblongata
 Continuation of spinal cord
 Ascending sensory tracts
 Descending motor tracts
 Nuclei of 5 cranial nerves
 Cardiovascular center
 force & rate of heart beat
 diameter of blood vessels
 Respiratory center
Medulla
 medullary rhythmicity area sets basic rhythm of breathing
 Information in & out of cerebellum
 Reflex centers for coughing, sneezing, swallowing etc
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Ventral Surface of Medulla Oblongata
 Ventral surface bulge
 pyramids
 large motor tract
 decussation of most fibers
 left cortex controls right
muscles
 Olive = olivary nucleus
 neurons send input to
cerebellum
 proprioceptive signals
 gives precision to movements
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Dorsal Surface of Medulla Oblongata
 Nucleus gracilis &
nucleus cuneatus =
sensory neurons
 relay information to
thalamus on opposite side
of brain
 5 cranial nerves arise from
medulla -- 8 thru 12
CN 7
CN 8
CN 9
CN 10
CN 11
CN 12
Nucleus
gracilis
Nucleus
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cutaneous
Injury to the Medulla
 Hard blow to the back of
the head may be fatal
 Cranial nerve malfunctions
on same side as injury;
loss of sensation or
paralysis of throat or
tongue;
irregularities in breathing
and heart rhythm
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Pons
 One inch long
 White fiber tracts
ascend and descend
 Pneumotaxic &
apneustic areas help
control breathing
 Middle cerebellar
peduncles carry sensory
info to the cerebellum
Pons
 Cranial nerves 5 thru 7
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Midbrain
Third
ventricle
 One inch in length
Cerebral
aqueduct
 Extends from pons to
diencephalon
 Cerebral aqueduct
connects 3rd ventricle
above to 4th ventricle
below
Midbrain
Fourth
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ventricle
Midbrain in Section
 Cerebral peduncles
Red nucleus
 clusters of motor & sensory
fibers
 Substantia nigra
Substantia
nigra
 helps controls subconscious
muscle activity
 Dopamine
 Red nucleus
 rich blood supply & ironcontaining pigment
 cortex & cerebellum
coordinate muscular
movements by sending
information here from the
cortex and cerebellum
Cerebral
peduncles
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Dorsal Surface of Midbrain
Superior
colliculi
 Corpora quadrigemina
 superior colliculi
 inferior colliculi
 coordinate eye
movements with visual
stimuli
Inferior
colliculi
 coordinate head
movements with auditory
stimuli
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Midbrain
 Superior, middle &
inferior peduncles attach
to brainstem
 inferior carries sensory
information from spinal
cord
 middle carries sensory
fibers from cerebral
cortex & basal ganglia
 superior carries motor
fibers that extend to
motor control areas
Superior
peduncles
Inferior
peduncles
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Reticular Formation
 Scattered nuclei in medulla, pons
& midbrain
Reticular
formation
 Reticular activating system
 alerts cerebral cortex to
sensory signals (sound of
alarm, flash light, smoke or
intruder) to awaken from sleep
 maintains consciousness &
helps keep you awake with
stimuli from ears, eyes, skin
and muscles
 Motor function is involvement
with maintaining muscle tone
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I.
Overview
II.
Brain Stem
III. Cerebellum
IV. Diencephalon
V.
Brain
Cerebrum
VI. Cranial Nerves
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Cerebellum
Vermis
 2 cerebellar hemispheres
and vermis (central area)
 Function
 correct voluntary muscle
contraction and posture
based on sensory data
from body about actual
movements
 sense of equilibrium
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Cerebellum
 Transverse fissure between
cerebellum & cerebrum
 Cerebellar cortex (folia) &
central nuclei are grey
matter
 Arbor vitae = tree of life =
white matter
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I.
Overview
II.
Brain Stem
III.
Cerebellum
IV.
Diencephalon
A.Thalamus
B.Hypothalamus
Brain
C.Epithalamus
D.Circumventricular Organs
V.
Cerebrum
VI.
Cranial Nerves
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Diencephalon Surrounds 3rd Ventricle
Thalamus
(enclosed in
3rd
ventricle)
 Surrounds 3rd ventricle
 Superior part of walls is
thalamus
 Inferior part of walls &
floor is hypothalamus
Hypothalamus
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Thalamus
 1 inch long mass of gray
mater in each half of
brain (connected across
the 3rd ventricle by
intermediate mass)
Thalamus
(enclosed in
3rd
ventricle)
 Relay station for
sensory information on
way to cortex
 Crude perception of
some sensations
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Thalamic Nuclei
 Nuclei have different roles
 relays auditory and visual
impulses, taste and
somatic sensations
 receives impulses from
cerebellum or basal
ganglia
 anterior nucleus
concerned with emotions,
memory and acquisition
of knowledge (cognition)
Emotions
Emotions
Emotions,
Alertness,
Memory
Auditory
Integrates
with other
nuclei
Visual
Motor
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Hypothalamus
 Dozen or so nuclei in 4 major
regions
 mammillary bodies are relay
station for olfactory reflexes
 infundibulum suspends the
pituitary gland
 Major regulator of homeostasis
Smell
 receives somatic and visceral
input, taste, smell & hearing
information; monitors osmotic
pressure, temperature of blood
Connects to
pituitary
gland
Pituitary
gland
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Functions of Hypothalamus
 Controls and integrates activities of
the ANS which regulates smooth,
cardiac muscle and glands
 Synthesizes regulatory hormones
that control the anterior pituitary
 Contains cell bodies of axons that
end in posterior pituitary where
they secrete hormones
 Regulates rage, aggression, pain,
pleasure & arousal
 Feeding, thirst & satiety centers
 Controls body temperature
 Regulates daily patterns of sleep
Smell
Connects to
pituitary
gland
Pituitary
gland
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Epithalamus
 Pineal gland
Pineal gland
 endocrine gland the size
of small pea
 secretes melatonin during
darkness
 promotes sleepiness &
sets biological clock
 Habenular nuclei
 emotional responses to
odors
Habenular
nuclei
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Subthalamus & CVO
 Subthalamus
 small area just inferior to
thalamus
 work with basal ganglia,
cerebrum & cerebellum to
control body movements
 Circumventricular organs
 in walls of 3rd & 4th ventricles
 monitor changes in blood
chemistry because lack blood
brain barrier (parts of
hypothalamus, pineal &
pituitary gland)
 sites of entry of HIV virus into
brain (dementia)
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I.
Overview
II.
Brain Stem
III.
Cerebellum
IV.
Diencephalon
V.
Cerebrum
VI.
A.
Lobes
B.
White Matter
C.
Basal Ganglia
D.
Limbic System
E.
Function of Cortex
1.
Sensory
2.
Motor
3.
Association
4.
Lateralization
5.
Brain Waves
Cranial Nerves
Brain
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Cerebrum (Cerebral Hemispheres)
 Cerebral cortex is gray
matter overlying white
matter
Gray matter
White matter
 2-4 mm thick containing
billions
of cells
 grew so quickly formed
folds
(gyri) and grooves (sulci
or fissures)
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Cerebrum (Cerebral Hemispheres)
Longitudinal
fissure
Corpus
callosum
 Longitudinal fissure
separates left & right
cerebral hemispheres
 Corpus callosum is band
of white matter connecting
left and right cerebral
hemispheres
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Lobes and Fissures

Each hemisphere is subdivided into 4
lobes
1.
Frontal lobe
2.

Motor area

Personality, behavior

Emotions

Memory
Occipital
Temporal
Somatosensory – skin and muscle
Occipital lobe

4.
Parietal
Parietal lobe

3.
Frontal
Vision
Temporal lobe

Hearing

Smell

Taste
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Lobes and Fissures
 Central sulcus (black)
 precentral & postcentral
gyrus
Frontal
Parietal
Occipital
Temporal
 Parieto-occipital sulcus
(red)
 Lateral sulcus (yellow)
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Cerebral White Matter
Association
fibers
1. Association fibers
between gyri in same
hemisphere
2. Commissural fibers from
one hemisphere to other
3. Projection fibers form
descending & ascending
tracts
Commisural
fibers
Projection
fibers
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Basal Ganglia
 Connections to red nucleus,
substantia nigra &
subthalamus
Caudate
 Input & output with
cerebral cortex, thalamus &
hypothalamus
 Control large automatic
movements of skeletal
muscles
 Parkinson’s Disease
Putamen
Globus
pallidus
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Limbic System
 Emotional brain
 intense pleasure &
intense pain
 Strong emotions increase
efficiency of memory
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Sensory Areas of Cerebral Cortex
 Receive sensory
information from the
thalamus
 Primary somatosensory
area = postcentral gyrus
= 1,2,3
 Primary visual area = 17
 Primary auditory area =
41 & 42
 Primary gustatory area =
43
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Motor Areas of Cerebral Cortex
 Voluntary motor initiation
 Primary motor area = 4 =
precentral gyrus
 controls voluntary
contractions of skeletal
muscles on other side
 Motor speech area = 44 =
Broca’s area
 production of speech -control of tongue &
airway
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Association Areas of Cerebral Cortex
 Somatosensory area = 5 & 7
(integrate & interpret)
 Visual association area = 18 &
19 (recognize & evaluate)
 Auditory association
area(Wernicke’s) = 22(words
become speech)
 Gnostic area = 5,7,39 & 40
(integrate all senses & respond)
 Premotor area = 6 (learned
skilled movements such as
typing)
 Frontal eye field =8 (scanning
eye movements such as phone
book)
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Hemispheric Lateralization
 Functional specialization of
each hemisphere more
pronounced in men
 Females have larger
connections between 2
sides
 Damage to left side
produces aphasia
 Damage to same area on
right side produces speech
with little emotional
inflection
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Electroencephalogram (EEG)

Brain waves are millions of
nerve action potentials in
cerebral cortex

diagnosis of brain disorders
(epilepsy)

brain death (absence of
activity in 2 EEGs 24 hours
apart)
1. Alpha -- awake & resting
2. Beta -- mental activity
3. Theta -- emotional stress
4. Delta -- deep sleep
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I.
Overview
II.
Brain Stem
III. Cerebellum
IV. Diencephalon
V.
Brain
Cerebrum
VI. Cranial Nerves
53
Cranial Nerves
I.
Olfactory
II.
Optic
III.
Oculomotor
IV.
Trochlear
V.
Trigeminal
VI.
Abducens
VII.
Facial
CN I
CN II
CN III
CN IV
CN V
CN VI
CN VII
VIII. Vestibulocochlear
IX.
CN VIII
Glossopharyngeal
CN IX
X.
Vagus
CN X
XI.
XII.
Accessory
CN XI
hypoglossal
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CN XII
I -- Olfactory Nerve (S)
 Extends from olfactory
mucosa of nasal cavity to
olfactory bulb
 Sense of smell
 Anosmia – loss of smell
55
II -- Optic Nerve (S)
Visual field defect
 Connects to retina
supplying vision
 Defect in
Visual acuity defect
 Visual acuity
 Visual field
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III = Oculomotor Nerve (S/M)
 Sensory:
Diplopia – double vision
 Proprioception – sense of position
 Motor:
 Levator palpebrae raises eyelid
 Ptosis – drooping of eyelid
 4 extrinsic eye muscles
 Superior, medial, inferior, and
inferior oblique
 2 intrinsic eye muscles
 accomodation for near vision
(changing shape of lens
during reading)
 constriction of pupil
57
IV = Trochlear Nerve (M)
 Sensory:
 Proprioception – sense of
position
 Motor:
 Superior oblique eye
muscle
58
V = Trigeminal Nerve S/M)

Sensory:

Tic douloureux - severe,
stabbing pain to one side
of the face.
touch, pain, &
temperature receptors of
the face
1. ophthalmic branch
2. maxillary branch
3. mandibular branch

Motor:

muscles of mastication
59
VI = Abducens Nerve (S/M)
 Sensory:
 Proprioception – sense of
position
 Motor:
 Lateral rectus eye muscle
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VII = Facial Nerve (S/M)
 Sensory:
 taste buds on anterior
2/3’s of tongue
Bell’s Palsy
 Motor:
 facial muscles
 salivary & nasal and oral
mucous glands & tears
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VIII = Vestibulocochlear Nerve (S/M)
 Cochlear branch begins in
medulla
 receptors in cochlea
 hearing
 if damaged deafness or
tinnitus (ringing) is produced
 Vestibular branch begins in pons
 receptors in vestibular
apparatus
 sense of balance
 vertigo (feeling of rotation)
 ataxia (lack of coordination)
62
IX = Glossopharyngeal Nerve (S/M)
 Sensory:
 Somatic sensations &
taste on posterior 1/3 of
tongue
 Motor:
 Stylopharyngeus m. (lifts
throat during
swallowing)
 Secretions of parotid
gland
63
X = Vagus Nerve (S/M)
 Sensory:
 Receives sensations from
viscera
 Motor:
 Controls cardiac muscle
and smooth muscle of the
viscera
 Controls secretion of
digestive fluids
Bradycardia
64
XI = Spinal Accessory Nerve (S/M)
 Cranial portion
 arises medulla
 skeletal mm of throat &
soft palate
 Spinal portion
 arises cervical spinal cord
 sternocleidomastoid and
trapezius mm.
65
XII = Hypoglossal Nerve (S/M)
 Sensory:
 Proprioception – sense of
position
 Motor:
 Controls muscles of
tongue during speech and
swallowing
 Injury deviates tongue to
injured side when
protruded
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