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anat 312 > lecture 28 - motor systems: spinal cord and brain stem > Flashcards

lecture 28 - motor systems: spinal cord and brain stem Flashcards

1
Q

what are the 4 classifications of movement?

A

reflexive, postural balance, volitional (reaching for a cup), and repetitive (walking)

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2
Q

list reflexive, volitional and postural balance in order from most automatic to least automatic

A

reflexive, postural balance, volitional

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3
Q

what are two divisions of the motor system

A

lateral and medial motor systems

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4
Q

describe the descending lateral pathway

A

cerebral cortex –>

  1. cerebellum –> red nucleus
  2. basal ganglia –> red nucleus
  3. directly to the red nucleus
    - -> sc
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5
Q

what is the descending lateral pathway?

A

rubrospinal

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6
Q

what are the 3 descending medial pathways?

A

vestibulospinal, reticulospinal, tectospinal

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7
Q

describe the descending medial pathways

A

cerebral motor cortex –> cerebellum/basal gang/direct –>

vestibulospinal: vestibular nuclei –> sc
reticulospinal: reticular formation –> sc
tectospinal: superior colliculus –> sc

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8
Q

provide a general overview of the ascending pathways of the motor system

A

cerebellum/basal ganglia –> thalamus –> cerebral cortex

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9
Q

what is a motor unit?

A

combination of a motor neuron and the muscle fibers it innervates

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10
Q

what are the rules for motor units?

A
  1. many motor neurons target each muscle
  2. each motor neuron targets only one muscle
  3. each muscle fibre is only innervated by one motor neuron
  4. when a motor neuron fires, all its fibers contract
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11
Q

what is a motor neuron pool?

A

collection of motor neurons whose axons all connect to the same muscle, although the neurons may be scattered across different levels of the sc

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12
Q

describe changes between the normal state and neurogenic disorders

A

loss of motor neurons

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13
Q

describe changes between the normal state and myogenic disorders

A

muscle fibre degeneration

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14
Q

describe the muscle at rest in its normal state, in neurogenic disorders and in myogenic disorders

A

normal: at rest
neurogenic: fibrillation
myogenic: fibrillation

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15
Q

describe the muscle during slight contraction in its normal state, in neurogenic disorders and in myogenic disorders

A

normal: regular, spaced out contractions
neurogenic: one giant contraction, lots of small irrgeular ones
myogenic: fibrillation: small polyphasic units (smaller and more irregular than normal)

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16
Q

describe the muscle during maximal contraction in its normal state, in neurogenic disorders and in myogenic disorders

A

normal: regular
neurogenic: reduced inference pattern
myogenic: full inference pattern but not as much range

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17
Q

describe histochemical changes from motor neuron loss

A
  • motor neuron dies
  • muscle fibres dennervated and die/atrophy
  • axons of surviving neurons tend to sprout and innervate dennervated fibres
  • muscle fibre types become clustered
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18
Q

is neuronal regeneration in the PNS slow or fast

A

slow

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19
Q

why can neuronal degernation occur in the motor system of the PNS?

A

because the targets are promiscuous

motor unit innervates multiple muscles, while sensory fields are less well-defined

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20
Q

explain the process of neuronal regeneration in the PNS

A
  • begins with injury to peripheral nerve
  • macrophages arrive and rapidly remove myelin debris
  • neuron expresses growth related genes
  • proliferating schwann cells promote axon regeneration
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21
Q

what are the two types of muscle spindles

A

primary and secondary

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22
Q

describe primary muscle spindles

A

largely respond to velocity of stretch

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23
Q

describe secondary muscle spindles

A

largely respond to muscle length

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24
Q

gamma motor neurons change what with respect to muscle spindles?

A

the excitability of spindle responses

25
Q

describe the deep tendon reflex

A

monosynaptic excitation of the agonist, disynaptic inhibition of the antagonist

(sensation immediately results in reflex)

26
Q

what would result in an increased deep tendon refelx?

A

upper motor neuron lesions

27
Q

what would result in a decreased deep tendon reflex?

A
  • acute upper motor neuron lesions

- peripheral, sensory, motor neuron and/or muscle abnormalities

28
Q

what muscles/tendons are involved in the upper extremity deep tendon reflex?

A

biceps, brachioradialis, triceps, patellar, achilles tendon

29
Q

what is the corresponding nerve root for the biceps?

A

C5, C6

30
Q

what is the corresponding nerve root for the brachioradialis?

A

C6

31
Q

what is the corresponding nerve root for the triceps?

A

C7

32
Q

what is the corresponding nerve root for the patellar?

A

L4

33
Q

what is the corresponding nerve root for the achilles tendon?

A

S1

34
Q

what is the function of the flexor reflex?

A

acts to lift foot away from painful stimuli

35
Q

what is excited and what is inhibited during the flexor reflex?

A 
flexors = excited
extensors = inhibited
36
Q

what is the function of the crossed extensor reflex?

A

acts to support the body on the other leg (when lifting one up for flexor reflex)

37
Q

what is excited and what is inhibited during the crossed extensor reflex?

A 
excited = extensors
inhibited = flexors
38
Q

do the flexor and the crossed extensor reflex go hand in hand

A

yes

39
Q

what generates the pattern of muscle leg activity?

A

central pattern generator in the spinal cord

40
Q

is the lateral vestibular nucleus ipsilateral or bilateral?

A

ipsilateral

41
Q

is the medial vestibular nucleus ipsilateral or bilateral?

A

bilateral

42
Q

what is the function of the lateral vestibular nucleus?

A

maintaining equilibrium, posture and vision w movement

43
Q

what is the function of the medial vestibular nucleus?

A

head and neck position

44
Q

is the pontine reticular formation ipsilateral or bilateral?

A

ipsilateral

45
Q

is the medullary reticular formation ipsilateral or bilateral?

A

ipsilateral

46
Q

what is the function of the pontine reticular formation?

A

posture and gait-related movement

47
Q

what is the function of the medullary reticular formation?

A

posture and gait-related movement

48
Q

is there a relationship btwn voluntary motor action and whole-body postural control?

A
  • yes - coordinate

- e.g., leg muscle turns on to stabilize the body before a voluntary arm movement

49
Q

is the superior colliculus ipsilateral or bilateral?

A

trick question! its contralateral

50
Q

what is the function of the superior colliculus?

A

coordination of the head and neck

51
Q

is the red nucleus ipsilateral or bilateral?

A

contralateral

52
Q

what is the function of the red nucleus?

A

coordination of sensorimotor info (limb control)

53
Q

2 posturing reflexes are associated with coma, true or false?

A

true

54
Q

describe flexor posturing during coma

A

patient flexes inwards (arms come into chest)

55
Q

describe extensor posturing during coma

A

patient flexes out (arms flex down at sides)

56
Q

flexor posturing is associated with what?

A

function above red nucleus (midbrain)

57
Q

extensor posturing is associated with what?

A

function below the red nucleus (midbrain)

58
Q

hint fot posturing during coma?

A

the higher the arms the higher the function

anat 312 (18 decks)

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