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Neurology > Motor systems II > Flashcards

Motor systems II Flashcards

1
Q

Which of Brodmann’s areas is associated with the primary motor cortex? Where in the brain is it found?

A

4

Found immediately anterior to the central sulcus

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2
Q

What is the result of lesions to the motor cortex?

A

Paralysis/paresis of specific muscle groups

the larger the lesion, the more muscle groups involved

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3
Q

If someone has a stroke involving occlusion of the MCA, what part of the brain is most likely to be affected and what consequences will this have?

A

Affect almost all of one side of the frontal lobe
result in severe motor disability in all parts of the contralateral body
(**apart from the LOWER limb - this part is supplied by the ACA)

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4
Q

What is worse, an infarction in the proximal segment of the MCA (M1) or in the distal segment (M3)? Why?

A

M1 - this will affect the blood supply to the basal ganglia via the lenticulostriate arteries and also affect blood supply to the motor cortex

If it was M3, it would only affect the motor cortex
(see diagram in lecture for further explanation if necessary)

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5
Q

What do the Brodmann areas 6 and 8 represent?

A 
6 = pre motor cortex
8 = supplementary motor cortex
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6
Q

What would damage to Brodmann areas 6 + 8 result in?

A

motor apraxia
- normal reflexes and no muscle weakness, but more difficulty in performing complex motor tasks

(however, if there is only damage to ONE side then the contralateral side may be able to compensate)

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7
Q

What Brodmann areas correspond to the posterior parietal cortex?

A

Areas 7 + 19

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8
Q

What would damage to areas 7 + 19 result in?

A

Sensory apraxia

= Difficulty performing complex motor tasks when triggered by sensory input (i.e. being asked to do something)

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9
Q

Where are the frontal eye fields and Broca’s area found?

A

Adjacent to the premotor area

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10
Q

What would damage to Broca’s area result in?

A

Motor aphasia

= difficulty generating speech output, and linking words into complex sentences

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11
Q

What would damage to frontal eye fields result in?

A

Oculomotor apraxia

= difficulty moving eyes horizontally and moving them quickly

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12
Q

If a patient has to turn their head to compensate for lack of eye movement, what might this indicate?

A

Bilateral lesions to the frontal eye fields

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13
Q

What Brodmann areas correspond to the somatosensory cortex?

A

1, 2 + 3

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14
Q

What Brodmann areas correspond to the dorsolateral prefrontal cortex?

A

9 + 10

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15
Q

What is the dorsolateral PFC responsible for?

A

planning movement, problem solving, judgement = executive functions

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16
Q

What are signs of damage to the dorsolateral PFC?

A

apathy
personality changes
lack of ability to plan/sequence actions
poor working memory for verbal/spatial information

(*can easily be damaged with impact to frontal bone)

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17
Q

What Brodmann areas correspond to the orbitofrontal cortex?

A

11

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18
Q

What is the orbitofrontal cortex responsible for?

A

control/inhibition of motor responses associated with the limbic system (hunger, thirst, sexual drive etc.)

19
Q

What can happen if the orbitofrontal cortex is damaged?

A

result in the disinhibition of the drives it is responsible for leading to pseudopsychopathic behaviour

20
Q

What is the VA/VL nuclei also called?

A

Motor thalamus

21
Q

What is the role of the motor thalamus?

A

Conveys motor commands from the basal ganglia + cerebellum to the corticospinal tract and LMNs

22
Q

Why is the corticobulbospinal tract vulnerable to damage via stroke?

A

It passes through the internal capsule on its way to the brainstem

23
Q

Where does the corticobulbar component of the CBST terminate in? What is the result of this?

A

terminates in various cranial nerve nuclei:
V + VII = cortical control of the muscles of the head
III, IV + VI = control of eye movements
also terminates in the pontine nuclei, reticular formation and red nucleus

24
Q

Where does the CST decussate?

A

Lower medulla (medullary pyramids) - forms large lateral and small medial CSTS

Then the motor decussation occurs in the upper spinal cord (C1-C5)

25
Q

What part of the spinal cord does the lateral and anterior CST run in?

A 
lateral = dorsolateral cord 
anterior = medial ventral cord
26
Q

Where is the only place in the body that the CST has monosynaptic connections with?

A

Thumb and digits

has spinal interneurones to initiate motor actions in other muscles

27
Q

What does damage to the CST result in?

A

Loss of control of hands and fingers
Posture/locomotion/gait not usually affected
Which side is affected depends on location of the lesion

28
Q

What other motor systems (not CST) mediate locomotion and gait?

A

Extrapyramidal systems

Main components of this: lateral vestibulospinal and the reticulopsinal tracts

29
Q

Where does the lateral vestibulospinal tract originate and what is its role?

A

Originates in the vestibular nuclei in the upper medulla and lower pons
Controls posture and balance

30
Q

Where does the reticulospinal tract originate and what is its role?

A

Originates in the reticular formation of the pons + medulla
Responsible for autonomic control (drives sympathetic preganglionic neurones)
Also provides the drive for respiration (phrenic nerve)
Plays a role in “general arousal” of the spinal cord

31
Q

Where does the rubrospinal tract originate and what is its role?

A

Originates in the red nucleus in the brainstem
Large muscle movement in upper limb - mainly flexion

It carries cerebellar commands to the spinal cord (as the red nucleus receives its main input from the cerebellum)

32
Q

What is the tectospinal tract, where does it originate and what is its role?

A

This is a minor extrapyramidal pathway
It originates in the superior colliculus and is also known as the optic tectum as it receives afferents from the retina
It is responsible for coordinating voluntary head and eye movements (reflex movements in head in response to visual + auditory stimuli)

33
Q

What is the medial vestibulospinal tract, where does it originate and what is its role?

A

Another minor extrapyramidal pathway and a continuation of MLF
it mediates reflex coordination of the head and neck muscles with the extraocular eye muscles to maintain objects in view

34
Q

Where do the UMNs act directly on the LMNS?

A

Thumbs + fingers

Lips + tongue

35
Q

Define spasticity. Is this the result of a UMN or LMN lesion?

A

Abnormally increase muscle tone and increased tendon reflexes
this is characteristic of a UMN lesion

36
Q

Define clonus.

A

series of jerky contractions of a particular muscle following sudden stretching of the muscle

37
Q

Define hyperreflexia.

A

Where an abnormally brisk tendon reflex is seen on one or more muscles

38
Q

What is decorticate posturing?

A

Arms are adducted and flexed (wrists + fingers flexed on chest)
Legs may be internally rotated and stiffly extended with plantarflexion

39
Q

What is decerebrate posturing?

A

Arms are adducted and extended (wrists pronated and fingers flexed)
Legs may be internally rotated and stiffly extended with plantarflexion

40
Q

Which is more serious, decorticate or decerebrate posturing?

A

Decerebrate - due to severe injury to the brainstem (below the level of the red nucleus), including damage to the CST and rubrospinal tract
- due to excessive activity in the EPS (esp. vestibulospinal tract)

41
Q

What are the acute effects of lesions of the motor mortex?

A

Initial paralysis
Weakness
Clumsiness + fatigue of movements
recovery will occur due to plasticity of the cortex (homonculus may change)
Larger lesions = slower recovery and permanent loss of certain movements

42
Q

What are the chronic effects of lesions of the motor cortex?

A

SMALL lesion = good recovery, but motor weakness and fatigue are always present
Hemiplegia dystonia = persistent flexion of arms and extension of legs due to persistent spasticity following a lesion

43
Q

What are the acute effects of spinal shock?

A

Paralysis/paresis

Reduced reflex response below level of the injury

44
Q

What are the chronic effects of spinal shock?

A

Shock wears off
Weak monosynpatic reflexes reappear
Crossed extensor reflexes may also recover
These reflexes may become exaggerated and hyperactive
May have clonus and Babinski sign

Neurology (46 decks)

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