Hathaway Fiocchi
July, 2010
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Course objectives
Power points
Handbook
Anatomy 1 powerpoints to review the basics
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In Dr. G’s folder: “Nervous System (2 lectures)”
Make sure to go over Dr. Lannings ppts
because she added some stuff!
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What is the point of all this?
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Neuroanatomic diagnosis
Two questions to answer in this course:
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Is the nervous system involved in producing the
observed dysfunction?
Where is the nervous system damaged? =
neuroanatomic diagnosis
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Circle of Willis
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Vertebral aa. contribute to 1 Basilar a.
Internal Carotid aa. (2)
Rete Mirabile
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When you don’t have major blood supply from the
internal carotid
 Cow, Cat, Pig
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1 ventral spinal a.
2 Dorsal spinal aa.
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3 layers:
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Dura mater
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Most external
Thickest
Well innervated
Falx cerebri
Arachnoid:
 Middle layer
 Arachnoid trabeculae
 Arachnoid granulations: CSF drainage
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Pia mater:
 Innermost, closely adhered to the nervous tissue
 Highly vascular
 Assoc. with denticulate ligament of the spinal cord
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Epidural space
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Mainly potential space in brain
Fat and vessel filled space in spinal cord
 Used for injections
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Subdural space
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Potential space in both brain and spinal cord
Subarachnoid space
 Interdigitated with arachnoid trabeculae
 Contains CSF
 Sites in the brain for tapping and sites on spinal cord
Pia mater is same in the brain and spinal cord
 Arachnoid
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 Specialized enlarged areas around the brain = cisterns
 Cerebellomedullary cistern is preferred site for CSF collection
in small animals and in large animals under anesthesia
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Dura Mater
 Outer and inner layer of the dura are closely adhered
 NO epidural space around the brain = potential space
 Big epidural space in the spinal cord = injections
 Dural reflections compartmentalize the brain and reduce
movement
 falx cerebri: midline of the cerebrum
Cranial Meninges and
Spaces
3 Layers
3 Spaces
Pia Mater
Dura
Mater
Where does
an Epidural
go?
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Filum terminale: Terminus of the spinal cord
Caudal ligament: Attachment of filum
terminale to last vertebral foramen
Lumbospinal cistern: for CSF tap in caudal
meninges-in the subarachnoid space around
the filum terminale
Epidural space is full of fat and vessels and can
be used for injections--carefully!
Can you label the:
Dura, Arachnoid, Pia,
Filum terminale,
Caudal ligament and
Lumbospinal Cistern?
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What space is used for collection of CSF?
- Subarachniod space
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What space is used for injections?
- Epidural space
In both cranial and caudal meninges?
No, caudal only—why?
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CSF: is an ultrafiltrate of blood
Produced by: ependymal cells of the choroid
plexuses within the ventricles
Drained by: arachnoid granulations—one way
valve system moves CSF into dural sinuses
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Dural sinuses are valve-less system
Functions
Water-jacket
 Lymphatics
 Transport hypothalamic hormones within brain
 CO2 concentration monitoring
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Vestiges of the neural tube within the brain
tissue and spinal cord
Lined with special glial cells called ependymal
cells of the choroid plexuses which help
produce and circulate the CSF within the
ventricles
Ventricles all connected and CSF flows from
cranial to caudal until the 4th ventricle
Flow of CSF through the ventricles: Lateral 
3rd  4th  arachnoid space (meninges) or
central canal
Try to superimpose
these 2 views in
your head to
understand the
relationship of the
ventricles in the
brain
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Damage to the cell body = death
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Damage to axons of the CNS = minimal regeneration at
best
Damage to axons of the PNS = more success
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To muscles and viscera!
3 types of injury to an axon
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Except: olfactory neurons which regenerate!
Stretch related
Lacerations
Compression (mechanical or vascular)
Extent of regeneration depends on the number and
severity of axons damaged
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Which of the following injuries has the best
chance of regeneration?
Damage to axon in CNS
 Damage to cell body in CNS
 Damage to axon in PNS
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Parietal Lobe
Occipital Lobe
Frontal Lobe
Cerebellum
Temporal
Lobe
Olfactory bulb
Pyriform Lobe
Optic Nerve
Brain Stem
Seat of consciousness and cognitive functions
 Receives all sensory information that reaches conscious
perception—not reflexes!
 Divided into 2 hemispheres: left and right
 Each hemisphere has 5 lobes
5 Lobes of the Cerebral Cortex
Parietal lobe:
- Perception of sensory
information to create a
3D map of the
world/body in space
- Damage causes
hemineglect
Parietal Lobe
Occipital lobe:
- Perception of visual
stimuli
- Damage causes
cortical blindness
- Reflex arcs are still
intact
Occipital Lobe
Frontal Lobe
Temporal
Lobe
Frontal Lobe
- Contains the sensory and
Pyriform Lobe
motor cortices
Pyriform Lobe:
- Initiation of movement
- Perception of
- Damage manifests in a
olfaction
delay of initiating
- Associated with the
movement or inappropriate
Limbic system
initiation
- Complete damage is
- Lesion is contralateral to
Anosmia
the side of manifestation
Temporal lobe:
- Processing of hearing
- Input from each ear goes to
BOTH left and right
temporal lobe
- MOST is contralateral
- Damage to one lobe does
NOT result in deafness even
in just one ear
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Sensory input
 Olfaction to pyriform
 (olfactory bulbs are technically considered part of the pyriform lobe)
 Auditory to temporal lobe
 Vision to occipital lobe
 Frontoparietal region for contralateral
somatosensory input
 Somatic sensation = the senses of touch, pressure, pain,
temperature
Association cortex: cognition and decision making
 Motor output from the motor cortex in the frontal
lobe
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Clinical signs of Cerebrum dysfunction
 Disturbances of consciousness
 Paresis of voluntary movement
 What is paresis?
 Disturbances of sensory function,
perception and seizures
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Limbic “Lobe” is a collection of cortical and
subcortical structures functionally linked by
their role in emotion and survival drives.
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What is a collection of cell bodies in the CNS called?
What is a collection of cell bodies in the PNS called?
Nuclei involved in the limbic system
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Hippocampus
Cingulate gyrus
Hypothalamus
Amygdala
Parts of thalamus
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All components of the limbic system assign
emotional and autonomic responses to sensory
experiences
Hypothalamus – regulates autonomic functions
and basic survival behaviors
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Amygdala – emotional memory formation; short
term
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Hunger, Satiety, Thirst, Temp, Osmoregulation, Circadian
rhythms
Assigning a fear response to a noxious stimuli
Hippocampus – converts short term memory to
long term memory
Limbic structure
Function
A. Hippocampus
1. Memory formation
B. Hypothalamus
2. Circacian Rhythm regulation
C. Amygdala
3. Osmoregulation
4. Satiety Center
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Maintains consciousness!
Receives collaterals from all sensory input and
dictates the level of arousal in the cerebral cortex
 Shapes selective attentions
 Pressure on hindbrain causes most common loss of
consciousness
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 Early compression  miosis
 Increased compression  mydriasis
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Canine Narcolepsy could be from a receptor mutation here that decreases
excitatory inputs from ARAS which would normally maintain
consciousness
What else comes from the hindbrain????
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BAR: Bright Alert Responsive
Oink! Are
you
Input from the cerebrum keeps
you “awake”
obtunded?
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ALERT: normal response to environmental stimuli
OBTUNDED: Withdrawn and unwilling to perform
normally
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DEMENTED: Animal is responsive, but the responses are
abnormal
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STUPOROUS: Patient unresponsive except to noxious
stimuli
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COMATOSE: Patient unresponsive to both environmental
and noxious stimuli
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A seizures is a cortical event characterized by
abnormal neuronal discharge that is both excessive
and hypersynchronized
 Can be caused by both excessive excitation or
decreased inhibition
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Prodrome (see Lanning’s ppt): early indicator of disorder
Aura: period of altered behavior
Ictus: synchronized, hyperactive firing of neurons is
occurring
 Associated with a loss of consciousness
 Alterations of sensation: hallucinations
 Disturbances of autonomic function: salivation,
tachycardia
 Alterations of muscle tone associated with involuntary
movements
Post-ictus: period of confusion and restlessness
Inter ictus (see Lanning’s ppt) periords between seizures
 Primary Focus: restricted area of the cortex when
the seizure begins
 Kindling: spreading or reinforcement of the
tendency to seize
 Mirror focus is when seizure spreads to the
contralateral side across the corpus callosum by
commissural fibers
 Focal seizure or partial seizure: the seizure is
confined to one part of the cerebrum, there are no
convulsions
 Focal motor seizure = chewing-gum fit
 Focal seizure with secondary generalization: neurons
outside the focus are recruited
 Usually within the limbic system
 Produces behavioral or emotional seizures
 Simple-partial seizure = term for seizure that does not
affect consciousness
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Generalized seizure: spreads rapidly to both
hemispheres, can have convulsions with loss of
consciousness
 Petit mal = no convulsions
 Seizures with convulsions and loss of consciousness:
 Grand mal AKA tonic-clonic AKA major motor
 Ictus is collapse, extensor rigidity, opisthotonus, apnea all
characteristics of the tonic phase
 Clonic phase: period of alternation between flexion and
extension of the limbs with violent chewing or vocalization
 “Paddling”
 Increased autonomic = salivation, urination, defecation
can also occur
Which cranial nerves have Parasympathetic
innervation?
III, VII, IX, X
What cranial nerves are tested with the gag reflex?
IX and X
What cranial nerve can regenerate its cell bodies?
I