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SF2- Exam 4 > Brainstem Motor Pathways > Flashcards

Brainstem Motor Pathways Flashcards

1
Q

What are the symptoms of a lesion to the lateral corticospinal tract?

A
  1. produces paresis and a loss of voluntary movements, especially at the digits
  2. positive Babinski sign
  3. decreased cremaster reflex
  4. produces hypotonia (loss of tonic stimulatory effect)
  5. does not produce spasticity.
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2
Q

What would result from a lesion of the anterior corticospinal tract?

A
  1. manipulation of objects normal
  2. frequent falling
  3. lost of righting reflex
  4. hypotonicity

NOTE: The anterior corticospinal tract has bilateral projections

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3
Q

When you talk about the upper motor neurons being lesioned you are usually referring to ________.

A

stroke.

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4
Q

True or False. Rigidity is dependent on velocity.

A

False.

Rigidity: an increase in extensor/flexor muscle tone characterized by resistance to passive stretch, independent of velocity.

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5
Q

What are the two types of rigidity?

A

a. lead-pipe: resistance constant throughout the range of movement.
b. cogwheel (Parkinson’s Disease) or clasp-knife (pyramidal tract): increase in passive resistance that abruptly decreases, usually at the end of an excursion.

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6
Q

Which type of rigidity is seen in Parkinson’s disease?

A

Cog wheel

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7
Q

Spasticity is an increase in muscle tone that is velocity _______ (dependent/ independent).

A

Dependent

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8
Q

Spasticity is greater in _______ of upper limb & __________ of lower limb.

A

flexors; extensors

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9
Q

Spasticity results from damage of _________parts of cortex and disinhibition of reticular and brainstem nuclei.

A

non-pyramidal

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10
Q

What are the major motor efferents from the cortex?

A
  1. Basal ganglia
  2. Cerebellum
    * Most projections go here but indirectly through the pons
  3. Spinal cord indirectly through
  • Red nucleus
  • Pontine reticular formation
  • Medullary reticular formation
  • Vestibular nuclei
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11
Q

Rexed lamina IX consist of two distinct groups of motor neurons:

A

1) medial group-axial musculature
2) lateral group-appendicular musculature

*The intermediate motor system isn’t quite lateral or medial, its not quite the hand and not quite the back. But it controls the muscles that position the hand and feet for proper orientation.

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12
Q

The medial motor system (anteromedial funiculus). These axons have a _________projection controlling the medial motor nuclei. It controls muscles that are more proximal. It goes to the medial part of the ventral horn, goes to axial and girdle musculature.

A

bilateral

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13
Q

There is a lateral extension of the medial motor system. This is the intermediate motor system. It’s the medial motor system (anterolateral funiculus). Goes to the intermediate muscles in the ______

A

ventral horn

*Unilaterl, ipsilateral projections the control proximal limbs

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14
Q

Medial pathway: Goes to the medial motor nuclei, activating the __________neurons/ interneurons that control large segments of the back and trunk, innervating proximal musculature, extensors (anti-gravity muscles) as opposed to flexors.

A

long propriospinal

*Rexed lamina ViII

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15
Q

Which muscles are primarily innevated by the medial pathway?

A

Proximal extensors

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16
Q

Which muscles are primarily innevated by the lateral pathway?

A

Distal Flexors

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17
Q

Lateral pathways: Lateral part of the ventral horn, target __________interneurons- neurons that connect different joints so you can move your limbs in coordinated fashion. Targets are muscles in the distal limbs and the output is predominately flexors as opposed to extensors.

A

short propriospinal

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18
Q

Label

A
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19
Q

The tectospinal tract come from the _________ and goes to the neck muscles so you can coordinate head movements.

A

superior colliculus

20
Q

In the lateral motor system, which of the two pathways is direct and which is indirect?

A

Direct: Lateral corticospinal tract

Indirect: Rubrospinal tract

21
Q

Label

A
22
Q

What are the two inputs to the red nucleus from the cerebellum?

A
  • Interposed (magnocellular)
  • Dentate (parvocellular)
23
Q

Rubrospinal tract crosses in the___________decussation and overlaps with the lateral corticospinal tract in the lateral funiculus

A

ventral tegmental

24
Q

Rubrospinal tract innervates proximal musculature of the ____________ (only).

A

contralateral upper limb

NOTE: It does not control individual digits

25
Q

Rubrospinal firing activity is related to the dynamics of ________ and limb ______

A

force; velocity

26
Q

Do the reticulospinal pathways have agonistic or antagonistic functions?

A

Anatagonistic

27
Q

The pontine reticulospinal tract is __________, while the medullary reticulospinal tract are _________.

A

medial; lateral

28
Q

Which vestibular nuclei give rise to the vestibulospinal tract?

A

Medial and lateral

29
Q

Label

A
30
Q

In slide, how do you know that you are at the pontomedullary junction?

A

Presence of dorsal and ventral cochlear nuclei

31
Q

The medial vestibulospinal tract

Originates from the __________

Terminates medially in the ventral horn of ________regions

Affects axial musculature of _______

Adjustments to ___________

A

medial vestibular nucleus

cervical

NECK

angular acceleration of head

32
Q

The lateral vestibulospinal tract

Originates from the _______________ ipsilaterally

Terminates in the _________ ventral horn group proximal limb muscles…balance

A

lateral vestibular nucleus (Deiter’s)

intermediate

33
Q

True or false. The lateral vestibulospinal tract does not cross over.

A

True

34
Q

The lateral vestibular system gets a lot of information from the ________

A

utricle

35
Q

It receives inhibitory input directly from Purkinje cells of the cerebellum, so the lateral vestibular nucleus will be modulated by the __________.

A

cerebellum.

36
Q

The lateral vestibulospinal tract receives tonically inhibitory inputs from the ___________.

A

Cortex

37
Q

What is the pathway of the tectospinal tract?

A
  1. Originates from the deep layers of superior colliculus
  2. Decussates in the dorsal tegmentum
  3. Terminates medially in the ventral horn of cervical cord

coordinates neck & eye movements

38
Q

The _____________ tract decussates in the dorsal tegmentum, which the __________ tract decussates in the ventral tegmentum.

A

Tectospinal; rubrospinal

39
Q

The cortex and red nucleus have a facilitatory influence on _______ tone.

A

flexor

*And inhibitory influence over extensors

40
Q

It’s the loss of the inhibitory influences of cortex on these pontine reticular spinal neurons that gives you the ___________- hyperextension in the neck.

A

opisthotonos

41
Q

The systems that try to maintain muscle tone of the flexors are ___________, __________, and ___________.

A

corticospinal, rubrospinal, and medullary reticulospinal.

42
Q

Antagonists to flexors will be the ___________ and ___________.

A

medial/lateral vestibulospinal systems and the pontine reticulospinal systems.

43
Q

Which motor neuron si problematc in decrebrate animals?

A

gamma

*because gamma system that adjusts the muscle tone, is increased.

44
Q

If you stimulate the anterior lobe of the cerebellum, you will reduce rigidity. Why is this?

A

The cerebellum has inhibitory input to the vestibular system. If you stimulate the cerebellum you increase the amount of inhibition of the vestibular spinal tract therefore rigidity is reduced

45
Q

Why do you get flexion of the upper limb in decorticating but in decerebrate you get extension?

A

Decorticate rigidity is when you have damage to the cerebral cortex or to the internal capsule

46
Q

The lesion for ________is above the red nucleus where as for ___________it is below the red nucleus.

A

decorticate; decerebrate

47
Q

A lesion of what places will cause decorticate symptoms?

A

Above the red nucleus

  • Cortex
  • Internal Capsule
  • Thalamus

SF2- Exam 4 (21 decks)

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