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SHB - Exam 3 > Motor System > Flashcards

Motor System Flashcards

1
Q

An UPPER MOTOR LESION of CN 7 will cause what?

What is a likely cause of this lesion?

A

contralateral paralysis of the LOWER face
(upper face spared)

  • STROKE
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2
Q

A LOWER MOTOR LESION of CN 7 (or Cranial nuclei) will cause what? What is a likely cause of this lesion?

A

ipsilateral paralysis of UPPER & LOWER side of face –> CANNOT CLOSE EYE (orbicularis oculi is non-functioning)

  • BELL’S PALSY
    so cut Cn 7 on left = left side of face wiped out (upper & lower)
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3
Q

What is a motor unit?

A

Muscle fiber & everything it innervates

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4
Q

What is an upper motor neuron?

A

anything above the Anterior Horn cells

but below the cerebellum, basal ganglia, and Association Cortex

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5
Q

What is the size principle? What is the order of the units?

test

A

There is a proportional increase in the muscle contraction

  • LMN’s are recruited in order of size & force**
    SS - FR - FF
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6
Q

Where does the Lateral Corticospinal tract located in the internal capsule? Where is the corticobulbar tract in the internal capsule?

(TEST)

A
  1. Posterior Limb of the INTERNAL CAPSULE (PL)

2. GENU = Corticobulbar

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7
Q

Where does the CST originate from?

A
  1. Motor cortex
  2. Adjacent areas
  3. Sensory cortex (somatosensory)
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8
Q

Where does the CST terminate?

A
  1. SPINAL CORD (anterior horn cells)
  2. BRAINSTEM
  3. Association cortex
    - Basal ganglia, thalamus, RT, sensory nuclei
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9
Q

Where is the Corticobulbar tract in the internal capsule?

A

GENU of the internal capsule (the bend)

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10
Q

Where does the Corticobulbar tract terminate? (2 areas)

A
  • terminates on INTERNEURONS of the RETICULAR FORMATION

- some on SPINAL MOTOR NEURONS

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11
Q

Which Cranial nerves does the Corticobulbar tract innervate? Which does it NOT innervate?

A
  1. 5,7,9,10,12

5 & 12 have more contralateral contribution (so opposite would be affected?)

  1. CN 3,4,6 of the eye are NOT innervated by Corticobulbar tract
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12
Q

What structures are innervated by the MEDIAL column of the LMN of the spinal cord? LATERAL?

What is dorsally places? Ventrally?

A
  1. AXIAL (leg/trunk)
  2. ARM - distal limb muscles
    = SOMATOTOPIC org.
  • DORSAL = flexor
  • VENTRAL = extensor
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13
Q

What do LMN’s release?

A

acetylcholine

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14
Q

What are corticospinal/corticobulbar neurons referred as?

A

UPPER MOTOR NEURON

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15
Q

What are neurons of the brainstem & spinal cord?

A

LOWER MOTOR NEURONS

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16
Q

Distinguish between the following three muscle units:

A
  1. S-units
    - slow twitch
    - ALOT of mitochondria & capillaries
    - not fatigueable
    - small force
    - RED MUSCLE fibers
  2. FR-units
    - fast twitch
    - WHITE fibers
    - moderate force
    - fatigue resistant
  3. FF-units (only fatiguable unit)
    - fast twitch
    - WHITE fibers
    - LARGE force
    - fatigueable***
17
Q

LMN’s are found in the white matter or the grey matter of the spinal cord? Which areas of the spinal cord have grey matter enlargement?

A

GREY MATTER

  • CERVICAL (arm) & LUMBOSACRAL (leg)
18
Q

What is the firing pattern of LMN’s dependent on?

A

INTERNEURONS

19
Q

What is the transmitter in Corticospinal tract? Is it excitatory or inhibitory?

A
  1. GLUTAMATE

2. Excitatory

20
Q

What are the 3 control systems for LMN’s?

A
  1. Descending Pathway
  2. Higher cortical centers
  3. Basal Ganglia & Cerebellum**
21
Q

Fibers in the CST are JUST localized in the MOTOR cortex. TRUE OR FALSE?

A

FALSE

  • they are in adjacent cortex & sensory cortex as well
22
Q

Where does the CST originate from?

A
  1. Primary motor cortex
  2. Adjacent Frontal Motor
  3. Parietal areas
    (somatosensory)
23
Q

CST descends through what?

A

POSTERIOR LIMB of the Internal Capsule

24
Q

If you lesion the PL, will this lead to ipsilateral loss or contralateral loss? What tract will be affected if you lesion the GENU of the internal capsule?

A
  1. CST in PL (fine motion)
    - CONTRALATERAL loss

(this is similar to a stroke)

  1. Corticobulbar Tract
25
Q

Where does the CST decussate?

A

Medullary Pyramids

  • most fibers = LATERAL corticospinal tract*
26
Q

What will occur if you lesion a PYRAMID before the CST crosses? What about a lesion in the spinal cord?

A

PYRAMID = OPPOSITE SIDE

SPINAL CORD = same side***

(fine motor movement affected)

27
Q

If you lesion the cerebellum, association cortex, or basal ganglia, will there be WEAKNESS?

A

NO

-

28
Q

Weakness only occurs in lesion of which 2 neurons?

A

UPPER MOTOR NEURONS +
LOWER MOTOR NEURONS
(anterior horn cells)

29
Q

What are the symptoms of a LOWER MOTOR NEURON lesion?

A
  1. Flaccid paralysis
  2. Hyporeflexivity
  3. Fasciculations
    * ATROPHY
30
Q

What are the symptoms of an UPPER MOTOR NEURON lesion?

A
  1. Spasticity
  2. Exaggerated reflexes
  3. Hemiplegia

-STROKE!!!

31
Q

The motor neurons of Cranial nerves, sensory relay nuclei, & RT is which tract?

A

CORTICOBULBAR

  • anterior to CST tract
32
Q

Where does the cortibulbar tract end?

A

Interneurons of the RETICULAR FORMATION

33
Q

Which nerves receive no direct corticobulbar innervation?

A

3,4,6

controlled instead by MLF

34
Q

A contralateral loss of the RIGHT lower face muscles would be indicative of what?

A 
LEFT STROKE (or lesion of the cortex)
CN 7
35
Q

An ipsilateral loss of the whole LEFT face would be indicative of what?

A

Bell’s Palsy

lesion CN7 or the nucleus

36
Q

What modulates the motor cortex?

A
  1. Association Cortex
  2. Basal Ganglia
  3. Cerebellum

(modulate via UPPER MOTOR NEURONS)

SHB - Exam 3 (21 decks)

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