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Spinal Cord Physiology > Spinal Cord Physiology > Flashcards

Spinal Cord Physiology Flashcards

1
Q

What color is the central, “H” shaped matter of the spinal cord?

A

grey

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2
Q

The dorsal (sensory) horn contains what two types of neurons?

A

interneurons and projection neurons

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3
Q

The ventral (motor) horn contains primarily what type of neurons?

A

motor neurons

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4
Q

The motor neurons of the ventral horn supply what two kinds of structures?

A

skeletal muscle and gamma motor neurons to muscle spindles arranged in groups

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5
Q

T/F

Only alpha motor neurons can cause skeletal muscle to contract

A

True

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6
Q

T/F

Alpha motor neurons are considered the “final common pathway”

A

True

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7
Q

Lesion of alpha motor neuron cause ______ type paralysis, in which case no reflexes can be elicited

A

flaccid

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8
Q

The intermediate area of the grey matter contains what types of neurons

A

interneurons and projection neurons as well as autonomic (visceral) motor neurons and sympathetic motor neurons

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9
Q

White matter axons lie is tracts ______ or ______ the spinal cord

A

ascending

descending

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10
Q

Lissauer’s tract is a feature of white matter or grey matter?

A

white matter

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11
Q

What type of fibers are located in Lissauer’s tract?

A

propriospinal fibers

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12
Q

The white matter is divided into ______, _____, and posterior funiculi. The posterior funiculus is aka ___________.

A

anterior
lateral
dorsal columns

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13
Q

What runs in the anterior fissure? In the posterior lateral sulcus?

A

anterior spinal artery

posterior spinal arteries

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14
Q

Rexed’s Laminae are numbered I-X. Laminae I-VII are part of the _____ horn. II and III are considered the __________ and are important in _________.

A

dorsal
substancia gelatinosa
pain transmission

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15
Q

Rexed’s Laminae are numbered I-X. Lamina VII is located in the __________ area. Lamiae VIII, which includes the interneurons of the anterior horn, and IX are in the ____ horn.

A

intermediate grey

ventral

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16
Q

Rexed’s Laminae are numbered 1-X. Lamina ___ consists of clusters of gamma and alpha motor neurons. Lamina X consists of ____________.

A

IX

grey matter surrounding central canal

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17
Q

There is a greater proportion of _____ matter at the upper cervical level.

A

White

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18
Q

T/F

The cervical enlargement for the UE is located at the mid to lower cervical level.

A

True

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19
Q

The thoracic level has a slender anterior horn. It also has an ______ cell column in the lateral horn.

A

Intermediate (preganglionic sympathetic)

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20
Q

In the lumbar level, is there more grey matter or white matter?

A

grey

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21
Q

The smallest diameter and the least amount of white matter is found in what level?

A

sacral

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22
Q

Muscle spindles respond to what kind of stretch?

A

quick and sustained

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23
Q

Muscle spindles provide CNS with information about static length and rate of stretch of a muscle, and tension with _______ contractions.

A

isometric

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24
Q

T/F. Muscle spindles only have a sensory component.

A

False.

Muscle spindles have both sensory component and motor component.

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25
Q

Muscle spindles (also called intrafusal fibers) are 10 mm long, which is longer or shorter than extrafusal fibers?

A

much shorter

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26
Q

Muscle spindle is enclosed in ___ capsule and the central portion is fulled with fluid and expands to about ___ mm, giving the spindle its characteristic shape.

A

CT

2

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27
Q

Which portion of the ms is contractile, the ends or the central portion?

A

the ends

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28
Q

The 2 types of intrafusal fibers are ____ fibers (nuclei clumped in central region), and nuclear chain fibers (nuclei _______).

A

bag

arranged in single file

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29
Q

The two types of sensory endings are ______ and _______.

A

primary (annulospiral)

secondary (flower spray)

30
Q

Primary/annulospiral sensory endings are __ adapting, have primarily ___ discharge, and are associated with type ___ fibers.

A

rapidly
plastic
Ia

31
Q

Primary (annulospiral) sensory endings will discharge in a burst of activity with a quick stretch and will also fire ____ with increasing or decreasing frequency depending on the amount of tension on the ms.

A

tonically

32
Q

Secondary (flower spray) sensory endings have primarily ____ discharge, are ____ adapting, and are associated with type ___ fibers which are myelinated, but slower than type Ia.

A

tonic
slow
II

33
Q

Secondary (flower spray) sensory endings are mainly on nuclear chain fibers off center to the primary endings. They respond to both ______ and ______.

A

passive stretch

active muscle contraction

34
Q

The 2 types of motor fibers are:

A

gamma dynamic axons

gamma static axons

35
Q

2 details about gamma dynamic axons

A

involved in maintaining gamma bias

innervate ends of nuclear bag fibers

36
Q

2 details about gamma static axons

A

maintain resting tension

innervate both types of fibers

37
Q

Describe the process of gamma bias

A

Purpose: make sure the ms is not put on slack when extrafusal fibers contract (which would make the ms insensitive to stretch)

gamma mn cause the contractile ends of the ms to contract in order to maintain the stretch on the central portion of the ms

38
Q

Some joint receptors respond phasically, others _____.

A

tonically

39
Q

Some joint receptors respond to the extremes of ROM, some to _______ ROM.

A

non-extreme

40
Q

Some joint receptors are ____ which transmit pain associated with tissue damage and inflammation.

A

free nerve endings

41
Q

Joint receptors and cutaneous receptors contribute to ____ and kinesthesia (sense of movement).

A

proprioception (position sense)

42
Q

Axons can be classified by:
1.
2.

A
  1. axon diameter

2. conduction velocity

43
Q

Small unmyelinated axons are associated with simple receptors conveing _____, temperature, and __.

A

crude touch

pain

44
Q

Large myelinated axons are associated with _____ and _______.

A

discriminative touch

motor axons

45
Q

The Monosynaptic stretch reflex/quick stretch reflex/DTR is stimulated by:

A

quick stretch of muscle

46
Q

in the DTR, there is _____ synapse on alpha mn, resulting in activation of alpha mn and contraction of stretched muscle (homonymous muscle) and inhibition of opposing _______ muscle.

A

direct

heteronymous

47
Q

Hyperreflexia is always a sign of UMN or LMN disorder?

A

UMN disorder

48
Q

Define recurrent inhibition

A

inhibition of the homonymous alpha mn via a collateral which excites an inhibitory neuron called a Renshaw cell.

49
Q

UMN

A

all motor neurons originating abouve the sc that have influence over activity of alpha mn

50
Q

LMN

A

refers to alpha mn (aka final common pathway…also includes gamma mn)

51
Q

T/F
Hyperreflexia with UMN lesion is due to removal of higher central control of the alpha mn causing ms to assume more influence over the alpha ms. Also due to reduction of inhibition because local inhibitory circuits are affected.

A

True

52
Q

Sustained Slow Stretch Reflex is usually inhibited by higher center’s influence on inhibitory interneurons in the spinal cord. Therefore, it is only seen following (UMN or LMN) lesions?

A

UMN

53
Q

During SSS, the primary ending is active only at onset and offset of stretch, while the ______ ending is active throughout the stretch.

A

secondary

54
Q

Afferant axons are both __ and __.

A

Ia and II

55
Q

During SSS, there is a synapse on an excitatory interneuron, which activates alpha mn in homonymous muscle and causes _______ of heteronymous muscle via inhibitory interneuron.

A

reciprocal inhibition

56
Q

SSS physiology is used in which PNF technique?

A

Hold Relax (submax contraction of agonist to inhibit antagonist)

57
Q

Autogenic Inhibition

A

Reflex loop where stretch receptor input from a receptor acts to inhibit that same muscle.

58
Q

What structure is thought to be responsible for autogenic inhibition?

A

GTO

59
Q

T/F

During autogenic inhibition, GTO input to the alpha mn on homonymous muscle is in inhibitory via inhibitory interneuron.

A

True

60
Q

Autogenic inhibition is the theory for which PNF technique?

A

Contract Relax (max contraction of antagonist to cause inhibition)

61
Q

The withdrawl reflex involves ___ via ________.

A

collaterals

Lissauer’s tract

62
Q

Except for the _______, all spinal reflexes involve interneurons.

A

Monosynaptic stretch reflex

63
Q

Reciprocal Inhibition

A

decreases activity in an antagonist when an agonist is active, allowing the agonist to act unopposed.

64
Q

Rexed’s Laminae

A

10 histologic and functionally specific regions in the spinal cord grey matter

65
Q

Propriospinal axons

A

axons that begin and end within the spinal cord

66
Q

A lateral horn exists at what levels?

A

T1-L2

67
Q

What type of motor neurons are contained in the lateral horn?

A

sympathetic motor neurons

68
Q

The axons of alpha motor neurons project to _______, branching into numerous terminals as they approach muscle.

A

extrafusal skeletal muscle

69
Q

Motor Unit

A

alpha motor neuron and the muscle fibers it innervates

70
Q

Phasic Stretch Reflex

A

muscle contraction in response to quick stretch

71
Q

Note:

A

The term phasic indicates that the frequency of action potentials in type Ia afferents is greatest during changes in spindle length and decreases when the spindle is maintained at a constant length

Spinal Cord Physiology (1 decks)

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