Descending Motor System (Exam 1) Flashcards

1
Q

What does paresis mean?

A

weakness (partial)

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2
Q

What does plegia mean?

A

No voluntary movement

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3
Q

What does paralysis mean?

A

No voluntary movement

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4
Q

What does palsy mean?

A

Weakness or no movement

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5
Q

What does hemi mean?

A

one side of the body

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6
Q

What does para mean?

A

both legs

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7
Q

What does mono mean?

A

one limb

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8
Q

What doe di mean?

A

both sides of body equally affected

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9
Q

What does quadri or tetra mean?

A

all four limbs

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10
Q

Where are the cell bodies located for upper motor neuron?

A

cortex or brainstem

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11
Q

Where does the upper motor neuron project to?

A

Descend within the CNS to govern activity of lower motor neuron cell bodies

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12
Q

Where are cell bodies located for lower motor neuron?

A

Spinal cord and brainstem

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13
Q

Where does the lower motor neuron projects to?

A

Muscles in the periphery

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14
Q

What is the criteria to be considered an Alpha motor neruon?

A

-Large cell body
- Target skeletal muscle

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15
Q

What is the criteria to be considered a Gamma motor neuron?

A
  • Smaller axon diameter
  • Target muscle spindles to help control stretch reflex
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16
Q

What is the criteria to be considered a Beta motor neuron?

A
  • Fewer in number
  • Innervate both muscles both within and outside of the muscle spindle
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17
Q

Where do lateral motor system UMN descend and synapse?

A
  • Lateral column of the spinal cord
  • Synapse on lateral ventral horn motor neurons (LMN) and interneurons
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18
Q

What muscles does the lateral motor system target?

A

distal limb muscles

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19
Q

Where do the medial motor system UMN descend and synapse?

A
  • Descend in the anteromedial columns of the spinal cord
  • Synapse on medial ventral horn motor neurons (LMN) and interneurons
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20
Q

What muscles does the medial motor system target?

A

Proximal axial muscle

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21
Q

What tracts are within the lateral motor system?

A
  • Lateral Corticospinal Tract
  • Rubrospinal Tract
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22
Q

What tracts are within the Medial Motor System?

A
  • Anterior Corticospinal Tract
  • Vestibulospinal Tract
  • Reticulopsinal Tract
  • Tectospinal Tract
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23
Q

Where do pyramidal tract originate and terminate?

A
  • Originate in cortex
  • Terminate on LMN cell bodies in brainstem (CNN) & spinal cord (anterior horn)
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24
Q

What does pyramidal tract control?

A

Volitional movement

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25
Q

Where do extrapyramidal tract originate and terminate?

A
  • Originate in brainstem
    -Terminate in spinal cord (LMN)
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26
Q

Extrapyramidal tracts are are modulated by and what do they control?

A
  • Modulated by other inputs
  • Control involuntary & automatic control of muscle tone, balance, posture & modulation of motor plans
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27
Q

Which of the lateral motor systems are pyramidal?

A

Lateral corticospinal tract

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28
Q

Which of the lateral motor system are extrapyramidal?

A

Rubrospinal Tract

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29
Q

Which of the medial motor system tracts are pyramidal?

A

Anterior Corticospinal Tract

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30
Q

Which of the medial motor system are extrapyramidal?

A

Vestibulospinal Tract
- Reticulospinal Tract
- Tectospinal tract

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31
Q

What is the origin of the lateral corticospinal tract?

A

Primary motor cortex and other frontal & parietal areas

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32
Q

Where is the decussation of the lateral corticospinal tract?

A

Pyramidal decussation at cervicomedullary junction

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33
Q

Where is the level of termination of the lateral corticospinal tract?

A
  • Lateral ventral horn
  • Entire cord
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34
Q

What is the function of the lateral corticospinal tract?

A

Volitional movement of contralateral limbs

35
Q

What fibers make up the Corticobulbar Tract?

A

Fibers project from the cortex to the brainstem

36
Q

Where is CN V (trigeminal - muscles of mastication) located?

A

Upper pons

37
Q

Where is CN VI (facial- lower facial muscles) located?

A

Lower pons

38
Q

Where is the CN XII (hypoglossal - tongue protrusion) located?

A

medulla

39
Q

Where is the origin of the rubrospinal tract?

A

Red nucleus

40
Q

Where does the decussation of the rubrospinal tract occur?

A

Ventral tegmental decussation (midbrain)

41
Q

Where is the level of termination of the rubrospinal tract?

A
  • Lateral ventral horn & intermediate zone
  • Cervical cord
42
Q

What is the function of the rubrospinal tract?

A
  • Movement of contralateral upper limb
  • Function uncertain in humans
43
Q

Lesions to the corticospinal tract above the red nucleus cause what posture?

A

Decorticate (flexor)

44
Q

Lesions to the corticospinal tract below the red nucleus cause what posture?

A

Decerebrate (extensor)

45
Q

Where does the anterior corticospinal tract originate?

A

Primary motor cortex and supplementary motor area

46
Q

Where does the decussation of the anterior corticospinal tract occur?

A

-Some remain ipsilateral
- Some cross in the ventral white commissure of the spinal cord

47
Q

Where is the level of termination of the anterior corticospinal tract?

A

Cervical and upper thoracic cord

48
Q

What is the function of the anterior corticospinal tract?

A

Bilateral axial & girdle muscles

49
Q

What is the origin of the medial vestibulospinal tract?

A

Medial & inferior vestibular nuclei

50
Q

Where does decussation of the medial vestibulospinal tract occur?

A

Descends bilaterally

51
Q

Where is the level of termination of the medial vestibulospinal tract occur?

A

Cervical & upper thoracic cord

52
Q

What is the function of the medial vestibulospinal tract?

A

Positioning of the head and neck

53
Q

Where is the origin of the lateral vestibulospinal tract?

A

Lateral vestibular nucleus

54
Q

Where does the decussation of the lateral vestibulospinal tract occur?

A

Does not cross

55
Q

Where does the lateral vestibulospinal tract terminate?

A

Enter cord

56
Q

What is the function of the lateral vestibulospinal tract?

A

balance

57
Q

Where does the medial vestibulospinal tract receive input from?

A

Semicircular canals (rotation)

58
Q

What does the medial vestibulospinal tract target, muscles does it activate and do?

A
  • Neck and proximal shoulder muscles
  • Activate extensors
  • Align head with body
59
Q

Where does the lateral vestibulospinal tract receive input from?

A

Primarily from otoliths (gravity and linear acceleration)

60
Q

What does the lateral vestibulospinal tract target, muscles does it activate and do?

A
  • Proximal limb and trunk muscles
  • Activate extensors & inhibits flexors
  • Postural alignment & balance
61
Q

What do both medial and lateral vestibulospinal tract do?

A
  • Activate postural extensors (antigravity muscles- involuntary)
  • Compensatory feedback response to postural instability detected by vestibular system
62
Q

Where does the reticulospinal tract originate?

A

Pontine & medullary reticular formation

63
Q

Where does the decussation of the reticulospinal tract occur?

A

Does not cross

64
Q

Where is the level of termination of the reticulospinal tract occur?

A

Entire cord

65
Q

What is the function of the reticulospinal tract?

A

Automatic posture and gait related movements

66
Q

Where does the reticular formation receive input from?

A

Cortex, hypothalamus, & brainstem

67
Q

What does the reticulospinal tract initiate?

A
  • Feedfoward adjustments to stabilize posture with planned movement
  • Assists with temporal & spatial coordination of limb & trunk movement
68
Q

Where does the tectospinal tract originate?

A

Superior colliculus (in tectum)

69
Q

Where does the decussation of the tectospinal tract occur?

A

Dorsal tegmental decussation

70
Q

Where does the tectospinal tract terminate?

A

Cervical cord

71
Q

What is the function of the tectospinal tract?

A

Coordination of head and eye movement

72
Q

What does the tectospinal tract allow?

A

Coordination of head and neck movements to orient towards visual stimuli

73
Q

What does the sympathetic part of the autonomic nervous system have?

A
  • T1-L2 (or L3)
  • Fight or flight
74
Q

What does the parasympathetic part of the autonomic nervous system have?

A
  • CNN and S2-S4
  • Rest and digest
75
Q

Where do preganglionic neurons travel in the sympathetic nervous system?

A
  • Paired paraverterbal ganglia which runs from cervical to sacral levels
  • Unpaired preverterbal ganglia
76
Q

Where do postganglionic neurons travel to in the sympathetic nervous system?

A

Distance to effector organ

77
Q

What do preganglionic neurons release in sympathetic nervous system?

A

Acetylcholine

78
Q

What do postganglonic neurons release in sympathetic nervous system?

A

Norepinephrine

79
Q

Where do preganglionic neurons in the parasympathetic nervous system travel to and release?

A
  • Travel long distance to terminal ganglia
  • Release acetylcholine
80
Q

Where do postganglionic neurons in the parasympathetic nervous system travel to and release?

A
  • Travel short distance to effector organ
  • Release primarily acetylcholine
81
Q

What other things give input to the autonomic nervous system?

A
  • Hypothalamus
  • Brainstem nuclei
  • Amygdala
  • Limbic cortex
  • Sensory afferents
  • Internal receptors
82
Q

What causes autonomic dysreflexia?

A

Caused by disconnect between the brain and the sympathetic neurons in the thoracolumbar spine

83
Q
A