Test 2: Descending Spinal Paths Flashcards Preview

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Flashcards in Test 2: Descending Spinal Paths Deck (54):
1

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

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

2

What is an UMN

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

3

What is the function of the lateral corticospinal tract

independant finger pointing
-monosynaptic
-CB in cortex-> rexed IX

4

What is the function of the rubospinal tract?

gross movement of hand
-CB in red nucleus of midbrain-> rexed VII

5

What are the 2 paths in the lateral motor system

lateral corticospinal
rubrospinal

6

Whata re the 4 paths in the medial motor system

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

7

What is the function of the ventral corticospinal tract

gross movement of head
-proximal limb/axial muscle control
-cortex to s.c

8

What is the function of the reticulospinal tracts

helps postural/anticipatory movement
-pontine=postural control
-medullary=locomotion
-retic formation to s.c.

9

What is the function of the vestibulospinal tracts

posture of head relative to space
-vestib nucleus to s.c.

10

What is the function of the tectospinal tract

vision controlling neck movements
-tectum to s.c.
-CB superior colliculus to s.c.

11

What are LMNs

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

12

What are gamma vs. alpha LMN?
What is coactivation?

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

activate together for proprioceptive feedback during contraction

13

What is indirect vs. direct control

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

14

What are examples of indirect motor control via brainstem UMN

Midbrain:
red nucleus- rubrospinal
superior colliculis- tectospinal

Pon/med:
reticular formation-reticulospinal tract
Vestibulonucleus

15

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

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

16

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

ventral corticospinal
medial vestibulospinal
tectospinal--CO

all end in cervical

17

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

medullary reticulospinal
pontine reticulospinal
lateral vestibulospinal

-all travel entire spinal cord

18

What is the BA for M1?

BA 4

19

What CB are in the M1?

lateral corticospinal tract
ventral corticospinal tract

20

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

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

Damage causes weakness

21

What is the BA for supplamentory motor area?

Pre-motor
BA 6

22

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

intrinsic given motor commands/bilateral activity
automatic and anticapitory movements

23

What does primary somatic sensory cortex help with?

some post-central cortex contributes to sensory movement

24

What is the cingulate motor area BA

24, 31, 23

25

What does the cingulate motor area function?

Emotive drive of LMN

26

What are PMd and SMA cortexes?

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

How many synapses are in the lateralcorticospinal pathways

MONOsynaptic primarily; some di and poly
UMN from M1 to LMN in cervical spine

28

Where does the pyramidal cell in lateral corticospinal tract synapse?

Rexed IX lateral or medial motor pool
-lateral pool to distal muscles
-medial pool controls pelvic, trunk, and girdle

29

Where do the pyramidal cells decussate?q

pyramidal decussation
-Medullary-sc junction

30

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

descend contralateral lateral corticospinal tract
synapse on LMN/interneuron in LATERAL motor column

31

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

Red nucleus
Decussate immediately in midbrain ventral tegmentum

32

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

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

33

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

10-15% of CST that DONT decussate
From M1 to bilatearl rex VII

34

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

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

35

Where does the ventral corticospinal decussate in the spinal cord?

Ventral commisure- rex VII

36

What are the functions of the reticulospinal pathways

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

37

Where do the reticulospinal and tectospinal tracts travel?

ALL central in the medial feniculus

38

Where are the CB of tectospinal

superior colliculus

39

Where does tectospinal decusate

central tegmentum of midbrain

40

Where does the tectospinal path go after decussation

down tectospinal tract to cervial cord

41

Where are the CB of the pontine reticulospinal

prontine reticular formation
-stays ipsilateral

42

Where does the pontine reticulospinal travel?

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

43

Where are the CB of medullar reticulospinal?

medullary reticular formation
-stays ipsilateral

44

Where does the medullary reticulospinal travel?

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

45

What is different about motor columns in the thoracic spine?

No lateral motor columns
-no limbs!

46

What are motor pools

alpha and gamma motor neurons for ONE muscle
ex: motor pool C5-7 for biceps

47

What are propriospinal neurons? Where are they?

In Rexed Vii
-connect and coordinate recruitment with many motor pools
-activates multiple SSC segments

48

What are commisural neurons

propriospinal neurons that coordinate motor pools bilaterally
-located medial= postural control
-located lateral= limb movements

49

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

muscle spindle
-control spindle length and register stretches even during contraction
-efferent axons sit at end of spindle past the afferents

50

What are long distance spinal circuits?

propriospinal circuits for proximal motor pools of UE and LE
Help muscles for posture

51

What are short distance local circuits?

propriospinal in same close together
muscle synergies to coordinate pools in local areas

52

What is the relex control spinal reflex

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

ONLY activate alpha NOT gamma

53

What is the flexor withdrawl of the spinal reflex

limb pulls away from stimulus
-interneurons recruited to excite ipsilateral LMN- flex
-interneurons inhibit ipsilateral extensor neurons
-allows quick withdraw

54

What is the crossed extensory spinal reflex

takes body weight and helps balance
-decusstes of interneuron to recruit contralateral excitatory reponse
-LMN control extensors- excites
-inhibits contrlateral flexors