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Neurology > Motor Systems > Flashcards

Motor Systems Flashcards

0
Q

What is the function of the BASAL GANGLIA in the motor system?

A

enforcement of desired movement
AND
suppression of undesired movements

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1
Q

What is the function of the CORTEX in the motor system?

A

planning, initiation of voluntary movement
AND
integration of inputs

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2
Q

What is the function of the CEREBELLUM in the motor system?

A

timing/precision of fine movement
adjusting ongoing movements
motor learning

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3
Q

What is the function of the BRAINSTEM in the motor system?

A

control of balance/posture

coordination of head, neck, eye movement

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4
Q

What is the function of the SPINAL CORD in the motor system?

A

reflexes, rhythmic movements, motor outflow

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5
Q

What is the function of the MUSCLES in the motor system?

A

movement of body

sensory organs

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6
Q

What is a motor unit?

A

A single neuron and all of the muscle fibers it innervates

SMALLEST division of the motor system can control individually

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7
Q

Describe Slow-Twich (Type I) muscle fibers

A
  • dark fibers (due to myoglobin)
  • aerobic metabolism
  • more myoglobin and MT
  • contract slower
  • less force
  • RESIST fatigue
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8
Q

Describe Fast-Twitch (Type II) muscle fibers

A

-Pale fibers
-anaerobic metabolism
more glycolytic enzymes
-contract fast
-more force
-FATIGUE fast

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9
Q

Describe Fast Fatigue-Resistant muscle fibers

A

intermediate b/t fast and slow fibers

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10
Q

What determines muscle type? (Fast-twitch, slow-twitch, etc)

A

Never innervation. NOT muscle fiber

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11
Q

Describe Muscle Fiber Recruitment

A

small motor neurons–> slow-fatigue
then medium motor neurons–> fast fatigue-resistant
then large motor neurons–> fast fatigue

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12
Q

Identify the 3 parts of the spindle

A

intrafusal fibers, afferent sensory neuron, and gamma motor neuron

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13
Q

Describe the afferents of the Dynamic Bag fibers and Static bag, and nuclear chain fibers

A

Dynamic Bag fibers–> Type 1a afferent, phasic response only to CHANGE to length
Static bag fibers and nuclear chain fibers—> Type 1a AND Type II afferents, no phasic response, gradual response

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14
Q

What do Golgi Tendon organs measure? Which afferent fibers go to Golgi tendons?

A

Measure tension. Type Ib afferent fibers.

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15
Q

Describe the topographical organization the spinal cord

A

Medial–> Axial muscles
Lateral–> Distal muscles
Ventral–> Extensors
Dorsal–> Flexors

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16
Q

What is the difference between medial and lateral interneurons?

A

Medial–> Bilateral projections. travel farther.

Lateral–> travel up and down a few segments, confined to one side

17
Q

What are the different interneurons and their functions?

A

Renshaw: stabilize motor neuron firing rates
Propriospinal: connect different spinal segments (medial and lateral interneurons)
Group 1a: Muscle Spindle inhibition of antagonist muscle, agonist-antagonist coordination
Group 1b: Golgi-Tendon Organ inhibition of agonist muscle to prevent excessive tension

18
Q

Describe the stretch reflex

A

Type Ia afferents from Muscle Spindle–> excite motor neuron of same muscle and synergistic muscles. Inhibit antagonist muscle through inhibitory Group Ia interneurons
Type Ib afferents from Golgli Tendon–> Inhibit motor neuron of same muscle through inhibitory Group 1b interneurons

19
Q

Describe Felxion Withdrawal Reflex

A

PAIN REFLEX
Flexion of same limb away from pain stimulus AND “Crossed-Extensor Reflex”–> extension of contralateral limb to maintain posture

20
Q

Upper vs. Lower Motor Neuron Disease (weakness, atrophy, reflexes, spasticity, Babinski)

A

UMN: weakness, NO atrophy, INCREASED reflexes, spasticity, and Babinski (+)

LMN: weakness, atrophy, DECREASED reflexes, NO spasticity, NO Babinski (-)

21
Q

Neurogenic vs Myopathic Disease (atrophy, fasciculations, loss of reflexes, creatine kinase, muscle biopsy, EMG)

A

Neurogenic: atrophy, fasciculations, loss of reflexes, NORMAL creatine kinase, Fiber-type grouping in muscle, FEWER and LARGER potentials on EMG

Myopathic: atrophy, NO fasciculations, loss of reflexes, INCREASED creatine kinase, muscle necrosis/regeneration on biopsy, and SMALLER potentials on EMG

22
Q

What is ALS?

A

Amyotrophy= muscle atrophy

Lateral Sclerosis= sclerosis (scarring) of lateral corticospinal tracts in spinal cord

23
Q

Describe the difference between Central and Peripheral Dysarthria

A

Central: “Spastic Dysarthria” speed is low, articulation is fairly clear

Peripheral: “Nasal Dysarthria” speed is normal, articulation is bad. Palatal weakness–> nasal quality

24
Q

Other Symptoms of ALS

A

weight loss, fatigue, pain (due to immobility)
psedobulbar affect (emotional lability) (Upper Motor Neurons)
depression (10%)
cognitive changes
bulbar symptoms–> hypoglossal nerve–> dysarthria, dysphagia, drooling, nasal regurgitation, aspiration

26
Q

Treatment for ALS (Multidisciplinary)

A

Respiratory care, weight maintenance, fall prevention, communication therapy, Pseudobulbar effects, pain, depression, spasticity, cramps, cognitive impairment

27
Q

What cells lie in Layer 5 of Primary Motor Cortex?

A

Betz cells of the corticospinal tract

28
Q

Naming of spinal nerves and vertebrae

A

C1-C7 share same # as vertebral segment BELOW it
C8 exits BELOW C7
Rest of nerves share same # as vertebral segment ABOVE it

29
Q

What is the difference between Cauda Equina Syndrome and Conus Medullaris Syndrome?

A

Cauda Equina Syndrome: Slow progression. Unilateral pain and areflexia, muscle atrophy. NO sexual dysfunction.

Conus Medullaris Syndome: Fast onset. Bilateral pain, reflexes present, incontinence. SEXUAL dysfunction

30
Q

Describe the Deep Tendon Reflexes (cord segment and muscle)

A 
Ankle jerk: S1, Gastrocnemius
Knee jerk: L2-L4, Quadriceps
Biceps: C5-C6, Biceps
Forearm: C5-C6, Brachioradialis
Triceps: C7-C8, Triceps
31
Q

What are the White Communicating Rami and Gray communicating Rami?

A

White: Myelinated Pre-ganglionic sympathetic fibers
Gray: Unmyelinated Post-ganglionic sympathetic fibers

32
Q

What is the Ventral Corticospinal tract?

A 
10% of descending corticospinal tracts that do not decussate with lateral corticospinal tract
Control posture, gross movement of neck, trunk, and lower limbs. 
Bilateral innervation (Ventral Commissure)
33
Q

Where does the Hypothalamospinal Tract project to? Lesion?

A

Interomediolateral cell column

Lesion: Horner syndrome

34
Q

What is the difference between fasciculations and fibrillations?

A

Fasciculations: spontaneous depolarizations of group of muscle fibers by 1 motor neuron
Fibrillations: small spontaneous depolarizations of single denervated muscle fiber

35
Q

What is Brown- Sequard Syndrome?

A

Loss of ALL sensation within 2 levels of lesion
Loss of IPSILATERAL motor function
Loss of CONTRALATERAL pain/temp below lesion
Loss of IPSILATERAL proprioception/fine touch on

36
Q

Describe the events at the NMJ

A

ACh–> NAChR–> influx of Na, K, an Ca through sarcolemma–> Ca-induced Ca release form SR–> Ca binds Troponin C–> removes tropomyosin from Myosin-binding sites on Actin–> myosin can bind actin–> muscle contraction

37
Q

Describe Myesthenia Gravis. How do you diagnose?

A

Autoimmune disease against NAChRs. Diagnosis via Tensilon Test (Edrophonium administration rapidly improves symptoms). This test is Negative in Lambert-Eaton.

38
Q

Describe Lambert-Eaton.

A

Autoimmune against presynaptic VG-Ca channels at NMJ.

39
Q

Clinically, what is difference between Myasthenia Gravis and Lambert-Eaton?

A

MG: associated with Thymoma. Muscles are WEAKER with repetition. Manifests with ptosis, diplopia, muscle weakness at END OF THE DAY.

LE: associated with small-cell lung cancer. Muscles are STRONGER with repetition. Manifests with difficulty rising from chair, weakness of large muscles IN THE MORNING. Muscle and ocular muscle involvement not as severe.

40
Q

What is the epineurium, perineurium, and endoneurium?

A

Epineurium: dense conn. tiss–> covers entire nerve.
Perineurium: permeability barrier. Surrounds fascicle of fibers. Must be rejoined in limb attachment.
Endoneurium: Surrounds single nerve fiber.

Neurology (11 decks)

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