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ANP Exam - T > Lec 20: Motor Skills > Flashcards

Lec 20: Motor Skills Flashcards

1
Q

3 Levels of Motor Skills

A
  1. Precommand level (highest)
  2. Projection level (middle)
  3. Segmental level (lowest)
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2
Q

Precommand Level

A

2 systems of neurons in the cerebellum and
basal nuclei that:
* start/stop movements
* coordinate movements with posture
* block unwanted movements
* monitor muscle tone

happens BEFORE actual
motor responses

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3
Q

Cerebellum

A

no access to spinal cord –
communicates with projection areas of brain stem and motor cortex via the thalamus

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4
Q

Basal Nuclei

A

Receive inputs from all cortical
areas and sent output primarily to premotor and prefrontal cortical areas via the thalamus
* seem to be involved in more complex
management compared to the cerebellum

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5
Q

Projection Level

A

neurons using direct and indirect motor
pathways (descending projection fibers)
* upper motor neurons of motor cortex
initiate direct (pyramidal pathways) to
muscles
* brain stem motor nuclei oversee the
indirect pathways; help to control reflex
and CPG-controlled motor actions
* in addition to descending pathways,
also send internal feedback to higher
command levels, continually informing
them of what should be happening

  • Primary Motor cortex
  • Brain stem nuclei
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6
Q

Segmental Level

A

reflexes and spinal cord circuits that control
automatic movements
* ventral horn neurons are activated and they stimulate certain muscles
* locomotion and other repeated patterns are called central pattern generators (CPGs): networks of oscillating inhibitory and excitatory neurons that set rhythms

  • Spinal Cord
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7
Q

Descending Motor Pathway

A
  • efferent impulses from brain to spinal cord
  • divided into 2 groups:
  • Direct Pathways = pyramidal tracts
  • Indirect Pathways = rubrospinal, vestibulospinal, reticulospinal and tectospinal tracts

90% of these neurons in lateral corticospinal
pathway; 10% in the smaller anterior pathway

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8
Q

Motor pathways involve 2 neurons

A
  • upper motor neuron begins in motor cortex
  • lower motor neuron is a spinal motor neuron or a cranial nerve motor neuron
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9
Q

Direct Pathways

What is the movement of the direct pathway?

A

Cortex - putamen - globus pallidus - thalamus - cortex

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10
Q

Direct Pathways

What is the job of the direct pathway?

A

-To influence the cortex
-Regulate fast and fine (or skilled) movements –
e.g. typing, playing a musical instrument

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11
Q

Spinal Cord Injury and Paralysis

A

transecting spinal cord at any level results in
total motor and sensory loss in regions
inferior to the cut

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12
Q

Spinal Cord Injury and Paralysis

  • Paralysis
  • Paraplegia
  • Quadriplegia
  • Hemiplegia
A
  • paralysis = loss of motor function
  • paraplegia: transection between T1 and L1
  • quadriplegia: transection in cervical region
  • hemiplegia: usually due to a brain injury
    rather than the spinal cord
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13
Q

Flaccid paralysis

A

damage to ventral roots or anterior horns means that impulses do not reach muscles and there is no voluntary or involuntary control of muscles

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14
Q

Spastic paralysis

A

damage to only upper motor neurons of primary motor cortex;
spinal neurons remain intact meaning that there is loss of voluntary control of
muscles but muscles can still be stimulated irregularly via spinal reflexes

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15
Q

Indirect Pathways

A
  • include brain stem, motor nuclei and all motor
    pathways not part of the pyramidal system
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16
Q

Indericet Pathways Tracts

A

includes rubrospinal, vestibulospinal,
reticulospinal and tectospinal tracts

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17
Q

Indericet Pathways Regulations

A
  • axial muscles for balance and posture
  • muscles controlling coarse limb
    movements
  • head, neck and eye movement to follow
    objects in visual field
18
Q

Direct Pathways (pic)

A
19
Q

Indirect Pathways (pic)

A
20
Q

Putting it all together

A
  1. Premotor cortex says “I want to do this”
  2. Precommand areas (basal nuclei and
    cerebellum) provide timing and patterns to
    execute the desired movements
  3. Basal nuclei are required to start
    movements (release motor centers from
    inhibition)
  4. Cerebellum calculates best way to perform
    and sends blueprint to motor cortex while
    constantly monitoring proprioceptive
    feedback
  5. Primary motor cortex sends signals down
    direct motor pathways
  6. Indirect pathways (from brain stem nuclei)
    assist with balance, eye movements,
    muscle tone
  7. Lower motor neurons receive signals from
    both pathways
  8. Sum total of all inhibitory and excitatory
    signals determines final response of the
    lower motor neuron & the skeletal muscles
21
Q

Reflex Arcs

A

Reflex arcs permit rapid and predictable responses
2 types: inborn (intrinsic) and learned (acquired)

22
Q

Inborn

A

unlearned, unpremeditated and involuntary – help us maintain posture, avoid
pain and control visceral activities without having to think about it
* e.g. drop pot of boiling water when some splashes on your arm

22
Q

Learned

A
  • results often from practice or repetition (e.g. experienced driver of a car)
  • can modify an inborn reflex by learning and conscious effort – e.g. what if your 3-
    year-old daughter were standing beside you when the boiling water splashed?
23
Q

— reflexes activate
skeletal muscle while
— reflexes
activate smooth muscle,
cardiac muscle or glands.

A

Somatic reflexes activate
skeletal muscle while
autonomic (visceral) reflexes
activate smooth muscle,
cardiac muscle or glands.

24
Q

Stretch and Tendon Reflexes

A
  • help you smoothly coordinate activity of skeletal muscles
  • nervous system needs to know:
  • length of the muscle (muscle spindles)
  • tension in the muscle plus tendons (tendon organs)
25
Q

2 types of afferent nerve endings:

A
  • anulospiral endings – from larger
    nerve axons and monitor both rate
    and degree of stretch
  • flower spray endings – from smaller
    nerve axons and monitor degree of
    stretch only
26
Q

Muscle can be stretched by:

A

a) external force or contraction of antagonistic muscle
b) activating motor neurons that put stretch on middle of the spindle

27
Q

All stretch reflexes involving the agonist muscle are

A

monosynaptic and ipsilateral

28
Q

The Tendon Reflex (polysynaptic)

A
  • acts in the opposite direction – muscles relax and lengthen in response to tension
  • contracting muscle relaxes as its antagonist is activated (reciprocal activation)
29
Q

Why is Tendon Reflex important?

A
  • protects against tearing when damaging stretching force is applied
  • during normal intensity of muscle contraction, help ensure smooth on and off
30
Q

Superficial Reflexes to Test for Spinal Cord Damag

Abdominal Reflex

A
  • using a tongue depressor, stroke skin that is lateral, superior or inferior to the
    umbilicus
  • should see movement of umbilicus toward site of stimulation due to reflex
    contraction of abdominal muscles
  • Tests integrity of T8 to T12
31
Q

Superficial Reflexes to Test for Spinal Cord Damag

Plantar Reflex

A
  • draw blunt object from heel to toe along lateral aspect of plantar surface of foot
  • should induce plantar flexion (except in infants less than 1 year)
  • Babinski’s sign (great toe dorsiflexes and remaining toes fan laterally) is
    indicative of damage to the primary motor cortex or L4 to S2 are damaged
    Babinski’s sign
32
Q

Effectors:

A
  • Somatic: skeletal muscle;
  • ANS: smooth muscle, cardiac muscle & glands
33
Q

Effectors

Somatic use — pathway

A

Acetylcholine

34
Q

Effectors

ANS (sympathetic) use — pathway

A

Norepinepherine

35
Q

Effectors

ANS (parasympathetic) use — pathway

A

Acetylcholine

36
Q

Pathways and Gangila

Somatic:

A

thick, myelinated axon from spinal cord to skeletal muscle; rapid
conduction of impulses (no ganglia)

37
Q

Pathways and Gangila

ANS:

A

two-neuron chain: preganglionic neuron: originates in brain or spinal cord;
preganglionic axon synapses with 2nd motor neuron (postganglionic) in
ganglion outside CNS – the postganglionic axon to effector organ
* conduction is slow; preganglionic axons are thin & lightly myelinated; postganglionic
axons are thinner & unmyelinated

38
Q

The sympathetic system

A

mobilizes the body during extreme situations

39
Q

The parasympathetic performs

A

maintenance activities and conserves energy

40
Q

Parasympathetic Division:

A
  • « resting & digesting system »
  • keeps body’s energy use low while regulating « housekeeping » activities (digestion,
    elimination of feces & urine)
  • “D” system: digestion, defecation, diuresis
41
Q

Sympathetic Division:

A
  • “ fight or flight” system; also important during exercise: increased heart rate, rapid,
    deep breathing, cold sweaty skin, dilated eye pupils
  • “E” system: exercise, excitement, emergency, embarrassment

ANP Exam - T (11 decks)

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