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Flashcards in Module 3 Deck (45):
0

Where is white matter found?

In all areas of the cerebrum
EXCEPT the cortex and basal ganglia

1

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

Projection
Association
Commissural

2

Describe the projection group

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

3

Describe the association group

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

4

Describe the commissural group

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

5

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

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

6

How are gross anatomy structures paired?

Bilaterally

7

What is the pyramidal pathway?

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

8

What does the pyramidal tract include?

Corticospinal
Corticobulbar

9

Where do the pyramidal tract originate from?

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

10

Describe the corticospinal pathway

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

11

Where does the decussation of the pyramids happen?

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

12

Describe the corticobulbar pathway

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

13

Where does the decussation of the corticobulbar pathway happen?

*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

14

What type of neurons does the pyramidal tracts have?

Upper motor neurons

15

What is the significance of the UMN?

Run from cortex to motor neuron cell body in the BS/SC
Within CNS but influence LMN

16

What is the significance of them LMN?

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

17

How do the projection pathways reach different areas?

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

18

what is the corona radiata?

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

19

What is the internal capsule?

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

20

What are the 3 main parts of the internal capsule?

Anterior limb
Knee (genu)
Posterior limb

21

What is the function of the anterior limb of IC?

Carries motor data
Carries affective and emotional data

22

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

Frontopontine (cortex to pons)
Corticostriate (cortex to BC/striatum)

23

Describe the genu knee of IC

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