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Neuroanatomy Lecture > Motor System and Reflexes > Flashcards

Motor System and Reflexes Flashcards

1
Q

Where is the primary motor cortex located?

A

precruciate and postcruciate gyri and the rostral suprasylvian gyrus

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2
Q

What are the motor tracts of the primary motor cortex?

A

lateral and ventral corticospinal tract

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3
Q

What are precise and refined voluntary control of extremities controlled by?

A

the contralateral side of the cerebrum

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4
Q

What percentage of motor fibers from the corticospinal tract terminate in cervical segments?

A

50

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5
Q

What percentage of motor fibers from the corticospinal tract terminate in thoracic segments?

A

30

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6
Q

What percentage of motor fibers from the corticospinal tract terminate in lumbosacral segments?

A

20

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7
Q

What are interneurons?

A

local circulatory neurons mediating signals between neurons

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8
Q

What are the type of interneurons?

A

excitatory, inhibitory, and renshaw cells

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9
Q

What do excitatory internuerons release?

A

Ach and glutamate

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10
Q

What do inhibitory interneurons release

A

GABA and glycine

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11
Q

What do renshaw cells release?

A

glycine

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12
Q

What does tetanus toxin do?

A

prevents the release of GABA and glycine from inhibitory and renshaw cells

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13
Q

What are the types of spinal motor neurons?

A

alpha motor neurons and visceral motor neurons

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14
Q

What are the alpha motor neurons located in and what type of motor neuron is it?

A

extrafusal muscles; lower motor neuron

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15
Q

What are the visceral motor neurons located in?

A

smooth and cardiac muscles

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16
Q

What is a motor unit?

A

a motor neuron and all of the muscle fibers it innervates

17
Q

What do motor units do?

A

generate appropriate contractile force of muscles needed for any given task

18
Q

What do upper motor neurons control?

A

lower motor neurons in the brain stem and spinal cord mostly via interneurons

19
Q

What do lower motor neurons innervate?

A

directly innervate muscles - skeletal, smooth, and cardiac

20
Q

What is a spinal reflex?

A

A relatively simple, stereotyped motor response to sensory input of sufficient intensity

21
Q

What is the myotatic reflex?

A

a reflex that induces stretching of the target muscle by tapping the associated tendon

22
Q

What nerve does the quadriceps reflex test the function of?

A

the femoral

23
Q

What cord segments does the quadriceps test?

A

L4-L6

24
Q

What muscle does the quadriceps reflex test test?

A

the quadriceps femoris

25
Q

What is the reflex pathway for the quadriceps reflex test?

A

muscle spindle to primary sensory neuron to motor neuron to skeletal muscle to golgi tendon organ

26
Q

What type of neurons does the reflex circuit use?

A

sensory, interneuron, and motor

27
Q

What are some spinal reflexes other than the myotatic reflex?

A

flexor (or withdrawal) reflex, crossed extensor reflex, perineal reflex

28
Q

How must the animal be positioned for the flexor/withdrawal reflex?

A

lateral recumbency

29
Q

How is the flexor or withdrawal reflex executed?

A

A stimulus to the foot triggers a flexion of the limb

30
Q

How must the animal be positioned for the crossed exensor reflex?

A

the animal must be standing

31
Q

How is the crossed extensor reflex executed?

A

Flex one limb, the opposite limb extends to support the increased weight on that limb

32
Q

How does the perineal reflex work?

A

Contraction of the anal sphincter and tail flexion in response to tactile stimulation of the perineum

33
Q

What nerves does the perineal reflex test test?

A

pudendal and caudal nerves

34
Q

What cord segments does the perineal reflex test test?

A

S1-S3

35
Q

What muscle does the perineal reflex test the function of?

A

anal sphincter and flexion tail muscles

36
Q

What is motor neuron disease classified by?

A

any disease that directly affects the function of motor neurons (perikarya and/or axons)

Neuroanatomy Lecture (17 decks)

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