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Neuro Anatomy > Test 2: Descending Spinal Paths > Flashcards

Test 2: Descending Spinal Paths Flashcards

1
Q

What are the 3 main function classes of descending spinal pathways?

A

Voluntary movement- internal activation
Automatic movement- more complicated than reflexes; dont need sensory input
Reflex movement- sensory input with motor output

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2
Q

What is an UMN

A

Motor cortex in origin of a descending path that goes to brainstem/s.c. neurons

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3
Q

What is the function of the lateral corticospinal tract

A

independant finger pointing

  • monosynaptic
  • CB in cortex-> rexed IX
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4
Q

What is the function of the rubospinal tract?

A

gross movement of hand

-CB in red nucleus of midbrain-> rexed VII

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5
Q

What are the 2 paths in the lateral motor system

A

lateral corticospinal

rubrospinal

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6
Q

Whata re the 4 paths in the medial motor system

A

ventral corticospinal
reticulospinal x2 (pontine and medullary)
vertibulblospinal x2
tectospinal

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7
Q

What is the function of the ventral corticospinal tract

A

gross movement of head

  • proximal limb/axial muscle control
  • cortex to s.c
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8
Q

What is the function of the reticulospinal tracts

A

helps postural/anticipatory movement

  • pontine=postural control
  • medullary=locomotion
  • retic formation to s.c.
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9
Q

What is the function of the vestibulospinal tracts

A

posture of head relative to space

-vestib nucleus to s.c.

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10
Q

What is the function of the tectospinal tract

A

vision controlling neck movements

  • tectum to s.c.
  • CB superior colliculus to s.c.
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11
Q

What are LMNs

A

alpha and gamma neurons in brainstem motor nuclei or spinal motor pools
-excitable fibers that produce muscle force

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12
Q

What are gamma vs. alpha LMN?

What is coactivation?

A

gamma: muscle spindles- intrafusal fibers
alpha: muscle fibers producing force

activate together for proprioceptive feedback during contraction

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13
Q

What is indirect vs. direct control

A

pyramidal (lamina V)cells control LMN in brainstem or spinal cord– muscle spindles and fibers= direct

pyramidal UMN relay to second UMN in brainstem to then control LMN–initiaites/recruits brainstem UMN

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14
Q

What are examples of indirect motor control via brainstem UMN

A

Midbrain:
red nucleus- rubrospinal
superior colliculis- tectospinal

Pon/med:
reticular formation-reticulospinal tract
Vestibulonucleus

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15
Q

How do you classify direct control pathways based on the amount of synapses?

A

monosynaptic: one UMN to LMN
disynaptic: UMN to interneuron (Rex VII or VIII) to LMN
polysynap: UMN to >1 interneuron (Rex VII or VIII) to LMN

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16
Q

What are the 3 medial tracts of medial motor systems in cross sections? Where do they terminate?

A

ventral corticospinal
medial vestibulospinal
tectospinal–CO

all end in cervical

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17
Q

What are the 3 more lateral tracts of medial motor systems in cross sections? Where do they terminate?

A

medullary reticulospinal
pontine reticulospinal
lateral vestibulospinal

-all travel entire spinal cord

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18
Q

What is the BA for M1?

A

BA 4

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19
Q

What CB are in the M1?

A

lateral corticospinal tract

ventral corticospinal tract

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20
Q

What to the tracts from M1 do? What would a lesion cause?

A

Volunatary/discrete movements for manipulation/initial movements
-CB innervate multiple LMN pools to recruit agonits

Damage causes weakness

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21
Q

What is the BA for supplamentory motor area?

A

Pre-motor

BA 6

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22
Q

What is the function of tracts from the pre-motor cortex?

A

intrinsic given motor commands/bilateral activity

automatic and anticapitory movements

23
Q

What does primary somatic sensory cortex help with?

A

some post-central cortex contributes to sensory movement

24
Q

What is the cingulate motor area BA

A

24, 31, 23

25
Q

What does the cingulate motor area function?

A

Emotive drive of LMN

26
Q

What are PMd and SMA cortexes?

A

motor association areas

  • higher order integration
  • complex tasks

PMD: anticapatory postural adjustments
SMA:internally motivated and bimanual movement

UMN recruits larger LMN pools compared to M1

27
Q

How many synapses are in the lateralcorticospinal pathways

A

MONOsynaptic primarily; some di and poly

UMN from M1 to LMN in cervical spine

28
Q

Where does the pyramidal cell in lateral corticospinal tract synapse?

A

Rexed IX lateral or medial motor pool

  • lateral pool to distal muscles
  • medial pool controls pelvic, trunk, and girdle
29
Q

Where do the pyramidal cells decussate?q

A

pyramidal decussation

-Medullary-sc junction

30
Q

After decussating in the pyramidal decussation where do the pyramidal cells travel in lateral corticospinal path

A

descend contralateral lateral corticospinal tract

synapse on LMN/interneuron in LATERAL motor column

31
Q

Where are the CB in the rubrospinal tract? Where do they decussate?

A

Red nucleus

Decussate immediately in midbrain ventral tegmentum

32
Q

Where do the rubrospinal neurons travel after decussating in the midbrain ventral tegmentum?

A

Lateral border of pons/medullary tegmentum
Join LCST path in LATERAL feniculus/column
-go to intermed zone Rex IV or VII interneurons

33
Q

Where is the ventral corticospinal tract CB and where does it go?

A

10-15% of CST that DONT decussate

From M1 to bilatearl rex VII

34
Q

Where does the ventral corticospinal tract travel down to the spinal cord?

A

Down ventral feniculus
Decussates at level in C-spine to synapse bilateral Rex VII
-Stops in C-spine
-all poly or disynap

35
Q

Where does the ventral corticospinal decussate in the spinal cord?

A

Ventral commisure- rex VII

36
Q

What are the functions of the reticulospinal pathways

A

Autonomic postural adjustments- heterogenous collection of neurons
Pontine: postural
Medullary: locomotion

37
Q

Where do the reticulospinal and tectospinal tracts travel?

A

ALL central in the medial feniculus

38
Q

Where are the CB of tectospinal

A

superior colliculus

39
Q

Where does tectospinal decusate

A

central tegmentum of midbrain

40
Q

Where does the tectospinal path go after decussation

A

down tectospinal tract to cervial cord

41
Q

Where are the CB of the pontine reticulospinal

A

prontine reticular formation

-stays ipsilateral

42
Q

Where does the pontine reticulospinal travel?

A

medial down entire spinal cord in rexed VII
-down central tegmentum
for POSTURAL

43
Q

Where are the CB of medullar reticulospinal?

A

medullary reticular formation

-stays ipsilateral

44
Q

Where does the medullary reticulospinal travel?

A

descend central tegmentum to entire s.c.
decussates in spinal grey at level
LOCOMOTION

45
Q

What is different about motor columns in the thoracic spine?

A

No lateral motor columns

-no limbs!

46
Q

What are motor pools

A

alpha and gamma motor neurons for ONE muscle

ex: motor pool C5-7 for biceps

47
Q

What are propriospinal neurons? Where are they?

A

In Rexed Vii

  • connect and coordinate recruitment with many motor pools
  • activates multiple SSC segments
48
Q

What are commisural neurons

A

propriospinal neurons that coordinate motor pools bilaterally

  • located medial= postural control
  • located lateral= limb movements
49
Q

What are gamma motor neurons? Why is their coactivation important?

A

muscle spindle

  • control spindle length and register stretches even during contraction
  • efferent axons sit at end of spindle past the afferents
50
Q

What are long distance spinal circuits?

A

propriospinal circuits for proximal motor pools of UE and LE

Help muscles for posture

51
Q

What are short distance local circuits?

A

propriospinal in same close together

muscle synergies to coordinate pools in local areas

52
Q

What is the relex control spinal reflex

A

When Adelta or C fibers are activated via noxious simultation-> cutaneous reflex circuit

ONLY activate alpha NOT gamma

53
Q

What is the flexor withdrawl of the spinal reflex

A

limb pulls away from stimulus

  • interneurons recruited to excite ipsilateral LMN- flex
  • interneurons inhibit ipsilateral extensor neurons
  • allows quick withdraw
54
Q

What is the crossed extensory spinal reflex

A

takes body weight and helps balance

  • decusstes of interneuron to recruit contralateral excitatory reponse
  • LMN control extensors- excites
  • inhibits contrlateral flexors

Neuro Anatomy (8 decks)

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