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Flashcards in B&B Anatomy Deck (170):
1

What are Meninges?

(epideral space)
►dura mater
(subdural space)
►arachnoid mater
(subarachnoid space - CSF)
►pia mater

Fx: protect CNS

Leptomeninges:
=arachnoid and pia mater

2

Which vertebrae contains the dens?

Dens is on Axis

Atlas sits on top of Axis

3

What is a "tract?"

bundle of axons

white matter
(due to fat content of myelin)

4

Brain

(C = cephalon)

►Forebrain (ProsenC)
●TelenC
– Cerebrum
– Basal Ganglion
●DienC
– Thalamus
– Hypothalamus
–Subthalmus

BRAINSTEM:
►Midbrain (MesenC)

►Hindbrain (RhombenC)
MetenC
– Pons
– Cerebellum
MyelenC
– Medulla

5

Brain
...vs...
Spinal Cord

What is the orientation of the white / gray matter?

►Brain:
Grey matter (superficial)
White matter (deep)

►Spinal Cord
White matter (outside)
Grey matter (inside)

6

What defines the CNS?

That part of the NS which is encased by bone (skull & vertebrae)

7

What does the limbic lobe contain?

Cingulate Gyrus

Para-hippocampal Gyrus

8

What produces CSF?

Ependymal Cells of the choroid plexus, which lines the ventricles

9

What are the components of the ventricular system?

Lateral Ventricles (2)
– Anterior Horn
– Posterior Horn
– Inferior Horn

Third Ventricle

Cerebral Aqueduct

Fourth Ventricle
– between the cerebellum and the pons

10

Which view?

Cut through the brain ventral to dorsal

Coronal Section

11

Which view?

Cut through the brain parallel to the horizon

Horizontal Section

12

Which view?

Cut through the brain anterior to posterior

Sagittal Section

13

Which layer is attached to the skull?

DURA MATER
• Perisoteal Layer
• Meningeal Layer
(fused; except in a few places where the inner layers form folds: "dural reflections"
– Falx cerebri
– Tentorium cerebelli

14

Arachnoid Granulations

What are they?

►Arachnoid Granulations

– Specialized portions of arachnoid that protrude into the super sagittal sinus

– involved in the reasborption of CSF

15

The three meningal layers form both real and potential spaces.

What do we mean by this?

REAL SPACES:
• exist under normal conditions
• only the subarachnoid space

POTENTIAL SPACES:
• do not exist under normal conditions
• becomes a real space pathologically, with blood accumulation

16

Epidural Space

When does it become a real space?

Epidermal Hematoma
– bleed from meningeal artery (following fracture of temporal bone)

XRay: lens-shaped biconcave hematoma

17

Subdural Space

When does it become a real space?

Subdural Hematoma
– Venous Hemorrhage (when shearing forces are applied to the head, the bridging veins can rupture, creating a real subdural space)

XRay: crescent-shaped hematoma

18

Subdural Hematoma

What are the 2 types?

►Acute Subdural Hematoma
– can develop following significant head trauma
– generally associated with other serious head injuries (brain contusion, subarachnoid hemorrhage) due to the impact velocity required to produce an acute subdural hematoma

►Chronic Subdural Hematoma
– develops slowly, over the course of weeks,
– generally due to minimal or no known history of trauma
– More common in elderly
– Sx generally vague due to slow progression
– Sx: headache, unsteady gait, cognitive impairment

19

Subarachnoid Space

Normally a real space ... but can become pathological.

What happens?

Subarachnoid Hemorrhage
– Arterial Aneurysm: remember that this is the space with CSF and vessels on surface of pia mater

XRay: Blood traces down into the sulci and follows the contours of the gyri

20

Subarachnoid Hemorrhage

What are the 2 types?

►Non-traumatic (spontaneous)
– generally caused by the rupture of an arterial aneurysm
– “worst headache of my life”

►Traumatic:
– more common
– caused by bleeding into the subarachnoid space following cerebral contusion
– Severe Headache

21

►Superior Swelling


►Inferior Sweeling

►Superior Swelling
– Cervical Enlargement
– C4-T1
– Brachial Plexus

►Inferior Swelling
– Lumbo-sacral Enlargement
– L2-S3

22

ID the iliac crests and draw a line across the back.

What vertebral level does that indicate?

L4

23

Where does the spinal cord end?

Between L1-L2

S2
(level of sacral dimples)

24

What extends from the conus medullaris?

Filum Terminalae
– extension of the pia
– attaches the caudal end of the spinal cord to the coccyx bone

Spinal Roots
– all the "hairs" that comprise the cauda equina

25

How does the measure of gray / white matter change throughout the spinal cord?

GRAY MATTER
(cell bodies)
– cervical & lumbar have more due to limbs

WHITE MATTER
– increases as move from caudal to rostral (cervical region has most white matter because it carries info from all levels of the spinal cord

26

Blood supply of Spinal Cord

Vertebral-Basilar System

Segmental Arteries

27

Antero-lateral System

►Awareness of Pain & Temp
– Spinothalamic Tract

►Modulation of Pain & Temp
– smaller tracts

28

Where does the Spinothalamic Tract terminate?

Terminates in the VPL nucleus of the thalamus.

From there, fibers project through the internal capsule and corona ratiata to terminate in the primary somato-sensory cortex

VPL = ventral postero-lateral

29

How are fibers from various levels organized in the spinal cord.

Cervical is Closest to the gray matter.

NOTE: in the posterior column:
Cerv & Thor = F. cuneatus
Lum & Sac = F. gracilis

30

Summary of 3 Pathways

⬆︎Spinothalamic
– pain & temp, crude touch
→ VPL nucleus of thalamus

⬆︎PCML
– discriminatory touch, proprioception, vibration
→ VPL nucleus of thalamus

⬇︎Corticospinal
►15% do not cross
Anterior corticospinal
– Postural Adjustments

►85% cross
Lateral corticospinal
– Skilled Voluntary Movement

31

Denticulate Ligaments

What are they derived from?

Pia

32

Corpus Callosum

Fx?

Connect two hemispheres

33

Complete hemi-section of spinal cord

What do we call this?

Sx?

Brown-Sequard Syndrome

– loss of contralateral pain, temp, crude touch

– loss of ipsilateral proprioception, discriminatory touch, vibration

– loss of ipsilateral UMN

34

Anatomy of Scalp

Comes off together:
– Skin
– CT (dense collagen)
– Aponeurosis

Loose CT
Periosteum

BONE:
– Outer Table
– Diploe (space)
– Inner Table

DURA MATER:
– Periosteal Layer (with Meningeal Art.)
– Meningeal Layer

35

Optic Canal

What travels through?

→ orbit:
CN II
&
Ophthalmic Artery

(blindness if either is lost)

36

Cribiform Plate

What travels through?

on top of nasal cavity; CN I is name of for all nerves travelling through

37

Superior Orbital Fissure

What travels through?

CN III, IV, VI

CN V.v1 Ophthalmic

Ophthalmic Veins

38

What is the "defect in bone?"

Foramen Lacerum (artifact): filled with cartilage in life - “defect in bone”

NOTE: Carotid Canal → Neck: Internal Carotid Artery (on angle)

39

►Foramen Rotundum

►Foramen Ovale

►Foramen Spinosum

What travels through?

►Foramen Rotundum
→ pterygopalatine foramen:
CN V.v2 Maxillary

►Foramen Ovale
→ Infratemporal fossa:
CN V.v3 Mandibular

►Foramen Spinosum
→ Infratemporal fossa:
Middle Meningeal Artery

40

Internal Acoustic Meatus

What travels through?

→ Neck:

CN VII

CN VIII

41

Jugular Foramen

What travels through?

→ Neck:
Internal Jugular Vein
CN IX, X, XI

42

Hypoglossal Canal

What travels through?

→ Neck:

CN XII

43

Foramen Magnum

What travels through?

spinal cord
&
vertebral arteries

44

Where is the 4th ventricle located?

Between cerebellum & pons

45

What occurs in the Pyramidal Decussation?

Fibres of the corticospinal tract cross the midline

(remember, motor fibres are in the pyramids and motor fibres are in the anterior!)

46

Modalities Carried by CNs

BASAL PLATE

1. GSE:
Motor info to skeletal muscles

2. SVE:
Branchial motor efferent - motor info to muscles of jaw, face, larynx, pharynx

3. GVE:
Preganglionic autonomic fibres to the core and periphery (parasympathetic)

47

Modalities Carried by CNs

ALAR PLATE

4. GVA:
Sensory info from viscera to core

5. SVA:
Sensory info about taste

6. GSA:
Sensory info from receptors in skin, muscle & joints

7. SSA:
Sensory info about vision, balance, or hearing

48

GSE

1. GSE
Motor info to skeletal muscles

BASAL PLATE

49

SVE

2. SVE
Branchial motor efferent - motor info to muscles of jaw, face, larynx, pharynx

BASAL PLATE

50

GVE

3. GVE
Preganglionic autonomic fibres to the core and periphery (parasympathetic)

BASAL PLATE

51

GVA

4. GVA:
Sensory info from viscera to core

ALAR PLATE

52

SVA

5. SVA:
Sensory info about taste

ALAR PLATE

53

GSA

6. GSA:
Sensory info from receptors in skin, muscle & joints

ALAR PLATE

54

SSA

7. SSA:
Sensory info about vision, balance, or hearing

ALAR PLATE

55

What is the Substantia Nigra?

key role in reward, addiction, movement

56

What mediates the communication between CN 3, 4, 6 for eye movement?

Ascending Medial Longitudinal Fasciculus (MLF)`

57

Cerebral Peduncles

Where are they located?

What do they do?

– prominent feature on the ventral surface of the midbrain,

– carry descending motor information.

58

Glossopharyngeal
CN IX

5 modalities

►GSA
General sensation: posterior 1/3 of the tongue, pharynx, external ear, tympanic membrane

►SVA
Taste from posterior 1/3 of tongue

►GVA
Carotid Body: chemoreceptors & barocreptors
Gag sensation from oral pharynx

►SVE
Stylopharyngeus Muscle

►GVE
Stimulation of parotid gland

59

Vagus
CN X

4 modalities

►GSA
Posterior meninges, skin of the back of the ear, external acoustic meatus, pharynx, larynx

►GVA
Larynx, throacic and abdominal viscera, aortic arch stretch receptors, chemoreceptors in aortic bodies

►SVE
Pharyngeal muscles
Instrinsic muscles of the larynx

►GVE
Thoracic & abdominal viscera
Smooth muscle and glands of the pharynx and larynx

60

Accessory
CN XI

GVE
Sternocleidomastoid (ipsilateral) → head turning
Trapezius (contralateral) →shoulder shrugging

61

CN XI

UMN vs LMN Lesion

UMN Lesion
Weakness of trapezius on contralateral side
Weakness of SCM on ipsilateral side

LMN
Weakness of trapeziums on ipsilateral side
Weakness of SCM on contralateral side

62

Where does the Infundibulim orignate?

Tuber Cinereum
bulge between optic chiasm and mammillary bodies

63

HYPOTHALAMUS

Fx:
Homeotstatic
Autonomic
Endocrine
Limbic

►Maintenance of homeostasis

►Regulation of food intake, body weight, electrolyte balance, body temperature, reproduction, sleep-wake cycle and circadian rhythms

►Controls the function of the pituitary gland via a neural connection with post pit (neurohypophysis) and a vascular connection to the ant pit (adenohypophysis)

►Influences on emotional, motivational, and affective aspects of behavior through links with the limbic system

64

HYPOTHALAMUS

Anterior Area Nuclei

ANT-POST AXIS
►Anterior Area Nuclei
– Anterior N.
– Suprachiasmatic N.
– Supraoptic N.
– Paraventricular N.

►Middle Area Nuclei
– Dorsomedial N.
– Ventromedial N.
– Arcuate Nuclei

►Posterior Area Nuclei
– Posterior N.
– Mamillary Body

LAT-MED AXIS
►Lateral Zone
– Lateral N.
►Medial Zone
...eating & drinking


65

Hypothalamus is ...

... structurally part of ?

... functionally part of ?

Structurally part of Diencephalon

Functionally part of Limbic System

66

Limbic System

Fx?

Major components?

Learning
Memory
Emotion
Bridge between endocrine & cortex

MAJOR COMPONENTS:
►Limbic Lobe
►Hippocampus
►Amygdala

67

What separates the Thalamus from the Hypothalamus

Hypothalamic Sulcus

68

Deep Strucutres of Limbic System:
►Hippocampus
►Amygdala

►Hippocampus
– memory
– located in floor of 3rd ventricle; deep to parahippocampus
– fibres emerge from posterior end that will form fornix, swing over the thalamus to reach mammillary bodies of hypothalamus

►Amygdala
1. Emotional learning and memory
2. Fear and fear conditioning
3. Reward
– located directly underneath uncus
– superior & anterior to hippocampus
– involved in Papez Circuit

69

Mamillothalamic tract

connects mamillary bodies with the anterior nucleus and the dorsal medial nucleus of the thalamus

From thalamus, info travels to limbic lobe

This completes PAPEZ CIRCUIT: learning, memory, emotion

70

Memory

SHORT TERM

LONG TERM
►Declarative (Explicit)
– Episodic (events)
– Semantic (facts)

►Non-Declarative (Implicit)
eg. skills, habits, emotional memories, conditional reflexes

71

Knowing how to ride a bike

►Non-Declarative (Implicit)
eg. skills, habits, emotional memories, conditional reflexes

72

Memory about facts or events

Declarative (Explicit)

73

Knowing what I ate for dinner last night

Episodic

74

Knowing the capital of BC

Semantic

75

Papez Circuit

Cingulate Gyrus

⬇︎Cingulum

Hippocampus

⬇︎Fornix

Mamillary Bodies

⬇︎Mammillothalamic Tract

Thalamus Anterior Nuclei

⬇︎Internal Capsule

Cingulate Gyrus

76

Blood Supply

Hypothalamus

►ANT Hypothalamus
●small branches from ...
– anterior cerebral
– anterior communicating arteries

►MID & POST Hypothalamus
●small branches ...
– from posterior cerebral
– posterior communicating arteries

77

Blood Supply

Hippocampus

►ANT Hip
– Anterior Choroidal Art.

►ANT & POST Hip
– Post Cerebral Art.

78

Blood Supply

Amygdala

Anterior Choroidal Artery

79

Blood Supply

Limbic Lobe

Anterior Cerebal Artery

Posterior Cerebral Artery

Anterior Choroidal Artery

80

The Cerebral Cortex can be organized based on function

►Primary Cortical Areas
– receive sensory info
– execute motor tasks

►Association Areas
– higher order processing
– Classified as...
• Unimodal
• Heteromodal

81

Primary Cortical Areas

Examples ...

• Primary Motor Area
• Primary somatosensory Area
• Primary visual Area
• Primary auditory Area
• Primary Gustatory Area

82

Association Areas

Examples ...

AA = Association Area

• Premotor AA
• Somatosenosry AA
• Visual AA
• Auditory AA
• Frontal AA
• Parietal / Sensory AA
• Temporal AA

83

Broca Area
...vs...
Wernicke Area

Broca Area
• speech production

Wernicke Area
• speech comprehension

84

Broca Area
Wernicke Area

How are they connected?

Connected by Arcuate fasciculus

This connecting network allows us to produce words that make sense and understand what is said and respond appropriately

85

Internal Capsule
Basal Ganglia

What is the blood Supply?

Lenticulostriate Arteries

(branches off the Middle Cerebral Artery)

86

Association Fibres

Commissural Fibres

Projection Fibres

►Association Fibres
– interconnect areas on the same side of the brain
– providing important integration to all lobes on the sames side of the brain

►Commissural Fibres
– cross the midline connecting the two hemispheres
– allow for integration of hemispheral networks into one functional unit

►Projection Fibres
– travel between crotex and brainstem
– allows for connection of the forebrain with the brainstem & spinal cord

87

Superior Longitudinal Fasciculus

– Association Fibre
– More compact in the middle region with fibres fanning out into the Frontal Lobe and Occipital Lobe
– Connects Front, Parietal, Temporal, and Occipital cortices for the integration of sensory info
– A subset of fibers forms the Arcuate Fasciculus, which connects language areas

88

The dominant hemisphere (almost always left) contains Broca's & Wernicke's

What about the non-dominant hemisphere?

The non-dominant hemisphere contains areas for melody, accent, tone of voice.

89

Where is the Brachiocephalic Artery?

On the R side.

Think about it. We have a subclavian & common carotid on each side of the body. But, the heart is on the left and so we need to have a "connection" to get over to the R side.

90

Innervation of Tongue

TASTE:
►Ant 2/3 CN7 via chorda tympani
►Post 1/3 CN9

SOMATIC SENSATION:
►Ant 2/3 CN5 v3
►Post 1/3 CN9
►Oral Pharynx CN10

91

Gag Reflex
Afferent
...vs...
Efferent

Afferent:
CN 9

Efferent:
CN 10

92

Waldeyer’s Ring

annular arrangement of lymphoid tissue in the pharynx

93

What does the Cerebellum do?

Brief Summary:
►micro-manager
►predictor
►coordinater
►automates movement

►receives and interprets proprioceptive information

►coordinates balance, it is tightly linked to the vestibular nuclei

►coordinates fine movement, eye-hand coordination it
(using tools)

►predicts the sensory consequences of movement (predicts the 'future' ... mentally prepares the body for a sensory consequence ...(e.g.)... predicting a next step, catching a ball)

94

What does the Cerebellum do?

(more!)

►the cerebellum can be considered the coordinator and predictor of cortical output (movement and cognition)

►info sent to the cerebellum can be used for the skilled manipulation of muscles

►info sent to the cerebellum can be used for the skilled manipulation of mental concepts

95

Functional Areas of Cerebellum

►Flocculonodular lobe (and vermis)
● Vestibulocerebellum connections
– trunk control

►vermis & anterior lobe
● Spinocerebellum connections
– syngergistic movement of extremities

►posterior lobe
● Cerebrocerebellar connections
– topographical representation of the extremities
– areas for eye movement and speech coordination of intricate and complex movements

96

Where does proprioceptive sensory info terminate?

terminates in anterior lobe (limbs) and vermis (trunk)

97

Why is the pons so big?

Pontine Nuclei!

Cortex projects to Pons which then projects to cerebellar hemispheres

98

Why can't you tickle yourself?

►Projections to and from the cerebellum predict movement and the sensory consequence of movement

►These predictions rely on sensory input from and output to the cortex as well as past learned experiences.

►Cerebellum predicts the sensory consequence of movement and then attenuates the response in the somatosensory cortex

99

Midline cerebellar disease

Lesion to Vermis

Sx


(NOTE: there are two main lesions to the cerebellum: (1) midline, or (2) lateral)

►gait difficulty

►truncal imbalance / Ataixa
– wide-based irregular steps
– veers to one side abnormal

►head postures
– head tilt

►oculomotor dysfunction
– nystagmus

100

Lesion fo Flocculonodular node

Sx?

very similar to midline (vermis cerebellar lesion)

►truncal imbalance
– wide-based irregular steps
– veers to one side abnormal

►head postures
– head tilt

►oculomotor dysfunction
– nystagmus

101

Lateral Cerebellar Lesion
(posterior lobe lesion)

affects posterior cerebellar loop → lose fine movement


Sx?

Hypotonia
– decreased resistance to passive movement

Dysarthria
– Slow laboured speech, garbled words; comprehension and grammar intact (output does't work)

Limb ataxia
– dysmetria (can't calculate and coordinate movements)
– decomposition of movement
– dys-diadocho-kinesia (lose of coordinated fine movement → eg. no longer able to play piano)

Intention tremor
– irregular, rhythmic tremor that increases as patient approaches a target

Impaired check
– difficulty of putting a limb back into the original position after it has been displaced

Occulomotor disorders
– gaze disorder, nystagmus

102

Normal function of Posterior Lobe of Cerebellum

►Posterior Lobe Function:
– Areas for eye movement and speech
– coordination of intricate and complex movements

103

Alcohol intoxication disrupts cerebellar function.

(Ethanol induced cerebellar ataxia)

How do police test?

Tandem Walk (walking in a line) requires really coordinated gait.

Affects Anterior Lobe of Cerebellum

Ethanol is toxic to the output cells in the cerebellum. Reversible ... but can be irreversible damage in severe chronic alcoholism.

104

What are the four key things that the cerebellum does?

►micro-manager
►predictor
►coordinater
►automates movement

105

What kind of control is the thalamus under?

Chronic Inhibition

Cortical input and output is regulated by the thalamus.
The thalamus is under chronic inhibition.

106

"Release-Inhibiition" Model of the Thalamus

►Direction Pathway
– releases the inhibition of the thalamus
(inhibition of the inhibition)
→ Leads to MORE cortical output

►Indirect Pathway
– enhances the inhibition of the thalamus
(excitation of the inhibition)
→ Leads to LESS Cortical output

107

Where is the cerebellum located?

Located in the posterior cranial fossa underneath the tentorium cerebelli

108

Cerebellum

What is it embrylogically related to?

How is it connected to the brainstem?

Embryologically related to pons

Connected to brainstem via cerebellar peduncles

109

What are the 3 cerebellar Loops?

►Vestibulocerebellar Loop
– Coordination of balance
– vestibulo-ocular reflex
– output to LMNs for trunk and limb stability

►Spino-cerebellar Loop
– Coordination and correction of trunk and limb movements

►Cerebro-cerebellar Loop
– Streamlining of corticol output

110

Lesion to the anterior lobe of the Cerebellum

Sx?

Affects spinocerebellar Input

Ataxia

(we see this in alcoholism as it is selective for the anterior lobe!)

111

Basal Ganglia

Main Functions

►Modulation of voluntary motor activity

►Balance of inhibitory and excitatory pathways gives input to the thalamus and from there to the cortex

►Three parallel circuits
– motor circuit controls body and eye movements
– associative circuit involved in higher level cognitive function
– limbic circuit involved in emotional and motivational processing

112

Sum it up ... in layman terms:

What does the Basal Ganglia do?

Make our movements and behavior more efficient

they proceduralize our movements

113

Activity in the Basal Ganglia encodes for ...

– The decision to move
– The direction of movement
– The amplitude of movement
– The motor expression of emotions
– Making movements and behaviour more efficient (proceduralization)

114

What is the natural state of the Thalamus

Thalamus is naturally inhibited

In order to talk to the cortex we need to dis-inhibit the thalamus

115

What are the functions of the Direct and Indirect Pathways?

• Direct and indirect pathways are happening simultaneously.

• Direct and indirect pathways provide a fine balance for cortical output.

• Target-oriented, efficient movements are facilitated (direct pathway) and superfluous competing movements are inhibited (indirect pathway)

• Together they streamline our movement, make it target-oriented and efficient.

116

Lesions of the Basal Ganglia

►Hypokinetic Movement Disorders
• Parkinson’s Disease is an example of inhibition of motor output.

►Hyper-kinetic Movement Disorders
• Ballism (striatum -
• Huntington’s Disease
• Neuropsychiatric disorders (Tourette’s Syndrome & OCD)

117

What is Ballism?

• large amplitude, non-rhythmic, sudden uncontrolled flinging movements of the extremities

• usually occurs only on one side (hemiballism) underlying cause is a lesion (stroke) of the contralateral subthalamic nucleus

118

Huntington's Disease

• Deficits in cognition, behavior and a characteristic hyperkinetic movement disorder.

• Brief, irregular unpredictable movements that move randomly from one part of the body to another (Chorea)

• Degeneration of the striatum (caudate and putamen).
CAG repeats on chromosome 4, abnormal levels of huntingtin.

119

Parkinson's Disease

• Degeneration of dopaminergic neurons of the substantia nigra.

• Decrease in movement (hypokinesia) or loss of movement (akinesia).

• Loss of facial expression - hypomimia

120

Parkinson's Disease

Damage to the substantia nigra: effects on both the direct and indirect pathways

What is the effect on the...
►Direct Pathway?
►Indirect Pathway?

►Direct pathway:
– less inhibition of the tonic inhibition of the thalamus: target oriented and efficient movements are not facilitated.

►Indirect pathway:
– GPe is inhibited, less inhibitory input to the STN, more excitatory input to the GPi, more inhibition of the thalamus.

121

Substantia Nigra

Why do we call it by this name?

appears black

due to melanin pigment

122

We have lots of inputs coming to the cortex.

How is it organized?

All is funneled through basal ganglia to become one target-oriented streamlined movement / motor output / behavior.

INTEGRATES EVERYTHING INTO ONE OUTPUT
(cerebellum does not do this ... it meticulously responds to every input ... does not integrate)

123

Akathisia

– excessive restlessness, urge to move around

– exact origin unknown

– appears to be associated with low dopamine

– problem with sensorimotor integration

– can get better with passive movement

124

Tibutation

nodding movement of head or neck

125

Flocculonodular Lesion

Problem with eyes & balance

126

Mononeuropathy

...vs...

Polyneuropoathy

Mononeuropathy
- one nerve affected
- or, more than 1 nerve affected in different locations

Polyneupoathy
- multiple nerves affected together
- commin in elderly
- "stocking & glove" pattern

127

Two types of peripheral Neuropathies

AxonProblem

Myelin Problem

Mixed

128

Ethanol Neuropathy

- pain in stocking distribution
- chronic
- numbness, parestheisas
- Sensory >>> motor

129

Patient presents to ER
● Ataxia
● Eye movement abnormalities
● Confused

Wernicke–Korsakoff syndrome
– Thiamine def (cofactor in Krebs)
– we have about a 3 week supply

Triad of Sx
● eyes don't move
● confused
● off balance

RISK FACTORS:
– alcoholism
– malnutrition
– protracted vomiting
– fever

130

How to treat?

THIAMINE

(do NOT give glucose first!)

This is going to be a classic exam question. The patient must get Thiamine BEFORE they get glucose!!!

131

Cerebellum

Thalamus VA/VL

Basal Ganglia

Cerebellum
– coordinator & predictor

Thalamus VA/VL
– Gate-keeper

BG
– Integrator

132

Where do the CN that control EM emerge from the brainstem?

CN 3
– Anterior midbrain
– just below Mammillary Bodies

CN 4 Trochlear
– Posterior (emerges from posterior!)

CN6 - Abducens
– Anterior
– Pontomedullar Jx

133

Where is the ...

● Vertical Gaze Center?

● Horizontal Gaze Center?

● Vertical Gaze Center
– midbrain

● Horizontal Gaze Center
– PPRF of pons

134

Smooth Pursuit

There is lots of things crossing the mid-line and it can be confusing.

Basically, what happens?

Frontal Eye Field & Visual Assoc. Cortex on one side ultimately direct horizontal gaze in the direction of that same side

aka...
L cortex
→ L pontine nuclei
CROSS...
→ Cerebellum
→ R Vestibular N
CROSS...
→ L Abducens
→ L Lat Rectus (& R Med Rectus)

135

Where are the olives?

Rostral Medulla

The olives are not very long. By the time we get to the caudal medulla, they are gone.

136

Pursuit Movement
...vs...

Pursuit movements
– controlled by the parieto-occipital cortex
– (eg) "H"
– Remember: "Pursuit - Parietal"

Saccadic Movements
– controlled by frontal cortex

137

A patient is unable to look to the R on command.

However, he IS able to perfectly follow the finger on the "H" test.

Where is the lesion?

Lesion:
– L Frontal Cortex

Rationale:
– "H" Test is normal, that is, pursuit movements are in tact.
– However, saccadic movements are NOT intact when looking to R.

138

What are the extra-ocular muscles of the eye?

►Orbicularis oculi
– closes the eyelid
– CN7

►Levator palpebrae superioris
– elevates the upper eyelid
– innervated by CN3
– lesion causes ptosis

139

Which nerve emerges from the dorsal surface of the caudal midbrain?

CN4
trochlear nerve

140

The semicircular canals give rise to information concerning ...

angular movements of the head.

141

In a lesion to the ventral root of T1, the pupil would be in which of the following positions relative to the pupil on the other side?

CONSTRICTION

Ratioale:
• T1 = sympathetic.
• A lesion to the sympathetic will result in pupil constriction

142

In lesions within the cavernous sinus, the first cranial nerve to be affected is usually what?

CN VI

Abducens

143

What does CN4 do?

Trochlear N → Sup Oblique (SO4)

Depresses the eye when adducted

144

What do Bipolar Cells of the retina do?

Bipolar cells effectively transfer info from rods & cones to ganglion cells.

(they have an excitatory synaptic action upon ganglion cells)

145

What does A positive Romberg sign indicate?

Indicates a problem with dorsal column function (Cerebellar lesion)

146

Oligodendrocytes are found only in white matter and never in gray matter

True / False

False

Apparently, Oligodendrocytes can be found in both white and gray

147

What are the 4 Parasympathetic Ganglion of the Head & Neck?

►ciliary ganglion
CN 3

►submandibular ganglion
CN 7

►pterygopalatine ganglion
CN 7

►otic ganglion
CN 9

148

Which nerve supplies the mucus covering the floor of the mouth?

Lingual Nerve

(branch of CN5 v3)

149

Which CN carries preganglionic parasympathetic nerve fibers for the parotid gland?

CN9 via Lesser Petrosal Nerve

150

Describe the nucleus ambiguus

Main motor nucleus for CN 9, 10, 11

Efferent fibres innervate voluntary striated muscle.

151

Thalamic Nuclei:

►centromedian.
►pulvinar.
►LGN
►reticular nucleus.
►VPL

►centromedian
– "non-specific" thalamic nucleus

►pulvinar
association nucleus

►LGN
– projection nucleus for vision.

►reticular nucleus

►VPL
–specific projection nucleus.

152

What is dysarthria?

What causes it?

Inability to speak

Tongue Motor Issue due to CN 12 lesion

153

Wallenberg's syndrome

"Lateral medullary syndrome"
"PICA Syndrome"

• Injury to the lateral part of the medulla
• Results in tissue ischemia and necrosis
• caused by thrombosis to PICA

154

On CT - What does a hyperdensity in the brain matter indicate?

Hyperdensity = white

Blood (hemorrhagic)
calcification
hypercellular lesions
IV contrast (dye)

155

What is the most common cause of intracerebral hemorrhage?

HTN

Other, less common causes:
• trauma
• infections
• tumors
• blood clotting deficiencies
• abnormalities in blood vessels (such as arterio-venous malformations)

156

Patient just arrived at ER.

CT confirms stroke

How to treat?

Octaplex & Vit K

“prothrombin complex concentrate”

Rapidly reverses the INR to a normal value. Must be given with Vit K to prevent rebound bleeding.

157

What are typical locations for hypertensive intercerebral hemorrhages?

• Basal Ganglia
• Thalamus
• Pons
• Cerebellum

Tend NOT to occur in the lobes (lobar hemorrhages) or near the cerebral cortex

HTN can result in subcortical hemorrhage due to vessels in these are located close to the high pressure of the circle of Willis

158

Lobar Hemorrhage

What causes it?

Occipital (cortical hemorrhage) is often called lobar hemorrhage

due to cerebral amyloid angiopathy

159

What is the Pterion?

It is the junction between four bones:
• parietal bone
• squamous part of temporal bone
• greater wing of sphenoid bone
• frontal bone

Located on the side of the skull, just behind the temple.

160

corticobulbar tract
"corticonuclear"

What is it?

• 2 neuron white matter motor pathway connecting the cerebral cortex to the brainstem primarily

• involved in carrying the motor function of the non-oculomotor CNs

• It is one of the pyramidal tracts (the other being the corticospinal tract)

161

What is the equivalent of the spinothalamic tract for the face?

Dorsal trigeminal tract

Enter pons → 1st order neurons descend to medulla, → form spinal trigeminal tract → synapse in spinal trigeminal nucleus.

Axons of 2nd order neurons cross the midline and terminate in the VPM nucleus of the thalamus

3rd order neuron in the thalamus then connects to the sensory cortex of the postcentral gyrus.

The midline nuclei 3rd order neurons then synapse to the cingulate and insular cortex.

162

►VPL
...vs...
►VPM

What passes through?

►ventral posterolateral nucleus (VPL)
• PCML

►ventral posteromedial nucleus (VPM)
• pain & temp from the face, head and neck
(facial)

163

The spinal trigeminal tract is present in the caudal medulla, but of course, it's not present in the remainder of the spinal cord as we move down.

What takes up the same spot in the remainder of the spinal cord?

Lissauer's Tract

aka "Dorsolateral Fasciculus"

164

What is the dentatorubrothalamic Tract?

Major output from cerebellar hemispheres via dentate nucleus and projecting to the VL/VA nuclei of the thalamus

165

Where is the Red Nucleus?

►Rostral Midbrain
– involved in motor coordination
– located in the tegmentum of the midbrain next to the substantia nigra
– comprises a caudal magnocellular and a rostral parvocellular part

166

Red Nucleus

Fx?

Comprises Rubrospinal Tract
Controls gait in those vertebrates WITHOUT a corticospinal tract

Humans have a corticospinal tract. Therefore, rubrospinal tract is considered vestigial. However, its role is:
• relays info from motor cortex to the cerebellum through the inferior olivary complex, an important relay center in the medulla
• controls crawling in babies, arm swinging in typical walking

167

Red Nucleus is comprised of a comprises a caudal magnocellular and a rostral parvocellular part

What is their roles?

►Parvocellular Part
(rostral)
– relays info from the motor cortex to the cerebellum through the inferior olivary complex, an important relay center in the medulla.

►Magnocellular Part
(caudal)
– controls muscles of the shoulder and upper arm

NOTE: Fine control of the fingers is not modified by the functioning of the red nucleus (rather it relies on corticospinal tract).

168

Lenticular fasciculus

What does it consist of?

►Lenticular Fasciculus
– consists of efferents from the globus pallidus to the thalamus.

169

Generally speaking, the CNs do not cross the midline

BUT, what are the exceptions?

CN4

CN 8 (auditory)

CN 11 (trapezius)

170

Decorticate
...vs...
Decerebrate

►Decorticate
– abnormal flexion
– above red nucleus
– mummy position
–damage to cerebral hemispheres, internal capsule, and the thalamus

►Decerebrate
– abnormal extension & internal rotation
– damage below the level of the red nucleus
– damage to brain stem damage or cerebellum