Module 3 Flashcards

0
Q

Name the 3 groups of white matter fibers also know as the medullary core

A

Projection
Association
Commissural

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1
Q

Where is white matter found?

A

In all areas of the cerebrum

EXCEPT the cortex and basal ganglia

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2
Q

Describe the projection group

A

Group of white matter pathway
Vertically organized
Connects the cortex to the Brainstem and spinal cord
Carries sensory and motor information

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3
Q

Describe the association group

A

Group of white matter pathway
Interconnects cortical area
Run within same hemisphere
Horizontally organized

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4
Q

Describe the commissural group

A

Group of white matter pathway
Interconnect cortical areas
Runs BETWEEN two hemispheres
Horizontally organized

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5
Q

What is the function of the groups of white matter pathways?

A

Informs brain on activity in and out of CNS
mediate info transfer between modalities
Coordinate activities between hemispheres

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6
Q

How are gross anatomy structures paired?

A

Bilaterally

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7
Q

What is the pyramidal pathway?

A
Major Motor projection system
Pyramidal tract (direct motor pathway)
Voluntary motor pathway
Initiation & control of skilled movements
Goes from the cortex to BS & SC
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8
Q

What does the pyramidal tract include?

A

Corticospinal

Corticobulbar

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9
Q

Where do the pyramidal tract originate from?

A

Primary motor cortex: 30%
Motor association cortex: 30%
Somatosensory cortex: 40%

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10
Q

Describe the corticospinal pathway

A
Cortex to spinal cord motor nuclei
Inner bates skeletal muscles of limbs
Carries motor commands 
Runs from cortex to spinal cord
Carrie motor commands from cortex to SC motor neurons
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11
Q

Where does the decussation of the pyramids happen?

A

Lower medulla
Lateral corticospinal crossed (90%)
Anterior corticospinal uncrossed (10%)

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12
Q

Describe the corticobulbar pathway

A

Runs from cortex to BS cranial nerves motor neuron nuclei
Innervates the speech muscles
Carries motor commands

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13
Q

Where does the decussation of the corticobulbar pathway happen?

A

*TRICK QUESTION**
This pathway has no major decussation
Neurons exit at various levels
Neurons exit pathway then cross to motor nucleus
Predominately contralateral innervation to speech muscles

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14
Q

What type of neurons does the pyramidal tracts have?

A

Upper motor neurons

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15
Q

What is the significance of the UMN?

A

Run from cortex to motor neuron cell body in the BS/SC

Within CNS but influence LMN

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16
Q

What is the significance of them LMN?

A

A peripheral motor neuron
Cell body in the BS/SC
Sends axons out to the muscles it serves
“The final common path”
Includes spinal and cranial motor neurons

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17
Q

How do the projection pathways reach different areas?

A

Through levels of the pyramidal tract:
Corona radiata
Internal capsule
Cerebral peduncles

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18
Q

what is the corona radiata?

A
Radiating projection system
Contains sensory/motor pathways
Between cortex and internal capsule
Diverges above
Converges below
19
Q

What is the internal capsule?

A

Bundle of nerve fibers
Same level of diencephalon
Both sensory/motor pathways
Part of continuous sheet of fibers to/from cerebral cortex

20
Q

What are the 3 main parts of the internal capsule?

A

Anterior limb
Knee (genu)
Posterior limb

21
Q

What is the function of the anterior limb of IC?

A

Carries motor data

Carries affective and emotional data

22
Q

Which pathways are used to carry motor data of the anterior limb?

A

Frontopontine (cortex to pons)

Corticostriate (cortex to BC/striatum)

23
Q

Describe the genu knee of IC

A

Corticobulbar pathway (cortex to BS cranial nerve nuclei & motor commands for speech)

Corticoreticular pathway

24
What is the corticoreticular pathway?
Cortex to BS reticular formation | Arousal and alertness
25
Describe the posterior limb IC: Motor
Corticospinal path Innervates limb and trunk muscles Travels through rostral end of Posterior limb
26
Describe the posterior limb IC: sensory
Project first to thalamus Travel thru caudal end of post. Limb Carry general/special sensory Corticopontine projections
27
Do ALL of the pathways to/from IC go through corona radiata?
True
28
What is the area below the IC?
Cerebral peduncles A.k.a crus cerebri A.k.a pea pedunculi
29
What is a projection system?
A continuous pathway Level of lesion significant (outcomes) Motor and sensory components
30
Name the 2 smaller white matter capsules
External capsule | Extreme capsule
31
What are association pathways?
Connect areas within the same hemisphere Gives bidirectional communication between cortical areas Have: long and short groups
32
Name the 4 important association pathways
Arcuate fasciculus Inferior occipital fasciculus Uncinate fasciculus Cingulum
33
What is the function of the arcuate fasciculus?
Interconnects all of the cortices of the 4 main lobes (fron, par, occ, temp) Connects wernicke's area and Broca's area
34
What is conduction aphasia?
Disconnection syndrome (arcuate syndrome) Posterior disconnected from anterior areas (wernickes/ Broca's areas disconnect) Good comprehension, reduced and impaired speech output
35
What is the function of the inferior occipital fasciculus?
Connects frontal lobe to occipital lobe and to inferior temporal lobes Crosses below lateral sulcus
36
What is the function of the uncinate fasciculus?
Connect orbital frontal with anterior temporal lobe cortex
37
What is the function of the cingulum?
Connects frontal, parietal and temporal areas with limbic lobe Follows cingulate gyrus Lesions impair emotion and affective behavior
38
Describe commissural pathways
Travel between hemispheres (interhemispheric pathways) Connect homologous structures in each hemisphere Makes bidirectional communication
39
Name the 3 brain commissures
Corpus callosum Anterior commissure Posterior commissure
40
What are the parts of the corpus callosum?
Rostrum (frontal areas) Genu (frontal areas) Body (parietal areas) Splenium (visual areas)
41
Lesions to the corpus callosum cause...
Communication impairment and coordination between hemispheres Impact depends in location of lesion Sectioning prevents spreading of seizures from one hemisphere to the other
42
What is the anterior commissure?
Interconnects temporal lobes | Anterior to thalamus
43
What is the posterior commissure?
Involved with midbrain visual (pupillary) reflexes | Posterior to thalamus
44
White Matter forms what part of the brain?
Medullary core