Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro Exam 2 > 5 Corticospinal Tract - M > Flashcards

5 Corticospinal Tract - M Flashcards

1
Q

What are upper motor neurons?

A

projection neurons from the primary motor cortex to the ventral horn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Function of UMNs?

A

modulate LMN activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are lower motor neurons?

A

final effectors/ motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where are the cell bodies of somatic LMNs found?

A

ventral horn of spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are the cell bodies of autonomic LMNs found?

A
  • ParaNS = motor nucleus
  • SymNS = lateral horn of spinal cord)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What two neuronal populations influence LMNs?

A

UMNs and segmental afferents of PCML tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe how a spinal reflex occurs?

A

sensory afferents send a branch to interneurons in spinal laminae which activate efferents in the ventral horn of the segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of LMN fibers active extrafusal fibers (skeletal muscle)?

A

Alpha fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of LMN fibers active intrafusal fibers (muscle spindles)?

A

Gamma fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to muscle spindles when UMN modulation is lost?

A

Muscle spindles become more sensitive = muscle weakness & spastic movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is the Ventral horn topographically arranged?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What spinal levels innervated the upper extremities?

A

C4-T1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What spinal levels innervated the lower extremities?

A

L1-S2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is flaccid paralysis?

A

LMN lesion resulting in complete loss of motor innervation to a muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 5 types of LMN lesion findings?

A
  1. flaccid paralysis
  2. areflexia
  3. atonia
  4. atrophy
  5. fasciculations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is atonia?

A

Loss of Gamma motor neuron activity = loss of muscle tone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is atrophy?

A

loss of muscle mass due to lack of innervation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are fasciculations?

A

twitching d/t increased sensitivity of motor end plates b/c of lesion to LMN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Damage to the ventral horn impairs what?

A

LMNs only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Damage to nerve roots (radiculopathy) causes what type of nerve impairment?

A

weakened motor and decrease sensory in a region

DTRs may +/-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Damage to peripheral nerves (neuropathy) causes what?

A

weakness & paraesthesia in specific muscle groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is Poliomyolitis?

A

Destruction of LMNs in the ventral horn by the poliovirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the signs of poliomyolitis?

A
  • fever
  • myalgia
  • Loss of muscle tone & reflexes with normal dermatome testing
    • Negative Hx for polio vaccine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does the corticospinal tract start?

A

Primary motor cortex

25
Q

What is the course of the corticospinal tract?

A
  1. primary motor cortex
  2. internal capsule of cerebrum
  3. cerebral peduncles (midbrain)
  4. anterior/rostral pons
  5. medullary pyramids –> decussates
  6. lateral CST (contralateral)

*anterior CST is different

26
Q

Does the lateral or anterior corticospinal tract crossover in the pyramidal decussation

A

Lateral corticospinal tract

27
Q

When do the “uncrossed” fibers of the anterior corticospinal tract crossover?

A

at the targeted spinal level

28
Q

The lateral corticospinal tract accounts for how much of the total fibers of the corticospinal UMNs?

A

85%; important for thinking about injuries

29
Q

Where is the lateral corticospinal tract located in the spinal column?

A

Posterior lateral funiculus, posterior to the ventral horn

30
Q

Where in the spinal column is the anterior corticospinal tract located?

A

Anterior funiculus along the anterior median fissure

31
Q

Is damage to the anterior corticospinal tract typically obvious?

A

No because it contain very few UMN fiber = minor modulator effect

32
Q

What are the 7 clinical presentations of a UMN lesion?

A
  1. spastic paralysis/paresis
  2. hypertonia
  3. hyperreflexia
  4. clonus
  5. rigidity
  6. disuse atrophy
    • babinksis reflexes
33
Q

What is spastic paralysis/paresis?

A

Velocity-dependent increase in resistance to passive movement, (typically in a specific direction

34
Q

What is hypertonia?

A

increased resting muscle tone due to loss of inhibitor signalling

35
Q

What is hyperreflexia?

A

increase in reflex due to loss of inhibition from UMNs

36
Q

What is clonus?

A

rapid series of alternating muscle contractions in response to a sudden stretch

37
Q

Does a UMN or LMN lesion cause a more serve a form of atrophy?

A

LMN causes more serve form

38
Q

What is a + Babinski’s reflex?

A

extension of hallux when planter surface is stroked (normal is to curl hallux)

39
Q

What are common causes of corticospinal tract lesions?

A

cerebrovascular accidents and spinal cord traumas (i.e. whiplash)

40
Q

How would a lesion of the R medullary pyramid above the decussation present?

A

Loss of UMN modulation on the LEFT SIDE = hypertonia, hyperreflexia, clonus, etc

41
Q

How would a right-sided lesion below the decussation present?

A

UMN loss on to right side = clonus, hypertonia, hyperreflexia, etc on right

42
Q

Why is a unilateral lesion in the medullary pyramids more serve than a lesion below the decussation

A

lesion above decussation = complete loss of UMNs to the contralateral side

Lesion below decussation = 85% loss of UMNs to the ipsilateral side & 15% loss of UMNs to the contralateral side

43
Q

What muscles are controlled by the lateral corticospinal tract?

A

skeletal muscle of the extremities

44
Q

What muscles are supplied by the anterior corticospinal tract?

A

axial (trunk) mucles

45
Q

Damage to the L ACA would result in loss of UMNs to what?

A

The contralateral LE > UE

46
Q

Damage to the R MCA would result in loss of UMNs to what?

A

The face and UE > LE

47
Q

Damage to the posterior limb of the internal capsule would damage what arteries and present how?

A

Lenticular/thalamostriatal arteries that supply the Lentiform nucleus = complete contralateral hemiparesis

48
Q

What is spinal shock?

A

Trauma to the spinal cord that results in LMNs s&s that recover in 1-2wks

* can cause spastic paresis

49
Q

What is cerebral palsy?

A

group of CNS disorders characterized by aberrant muscle control & posture

50
Q

What are the 4 main types of Cerebral palsy?

A
  1. spastic (cerebral cortex)
  2. dyskinetic (basal ganglia)
  3. ataxic (cerebellum)
  4. mixed (multiple areas)
51
Q

how is the type of cerebral palsy diagnosed?

A

By clinical presentations = indicated affected brain regions

52
Q

Clinical features of Amyotrophic lateral sclerosis (ALS)

A

mixed UMN & LMN signs

53
Q

What is the function of the reticulospinal tract?

A

Pontine activation of the antigravity reflexes when in erect positions

54
Q

What is the medullary reticulospinal pathway?

A

mediates cortical inhibitor control of reflexes

55
Q

Where does the rubrospinal tract originate from?

A

Red nucleus of the midbrain (in the tegmentum)

56
Q

What type of voluntary movement is controlled by rubrospinal tract?

A

flexor movement

57
Q

What nucleus originates in the superior colliculus and coordinates head and eye movements

A

tectospinal tract (originates in tectum)

58
Q

What tract maintains postures against gravity and UE/LE extensors?

A

Vestibulospinal tract from vestibular cortex

Neuro Exam 2 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions