Neuroanatomy and Physiology of the Spinal Cord Flashcards

1
Q

What region of the neural tube lies ventral to the sulcus limitans?

A

Basal plate

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2
Q

What region of the neural tube lies dorsal to the sulcus limitans?

A

Alar plate

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3
Q

What part of the spinal cord contains primarily motor neurons (efferent)?

A

Basal plate

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4
Q

What part of the spinal cord contains primarily sensory neurons (afferent)?

A

Alar plate

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5
Q

Is the spinal cord longer in men or women?

A

Men (45cm compared to the 42cm in women)

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6
Q

What is the approximate diameter of the spinal cord?

A

1.0-1.5cm

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7
Q

In adults, the spinal cord ends at what vertebral level?

A

L1-L2

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8
Q

There are 2 observable enlargements that occur in the spinal cord. Where do these occur?

A
  • cervical

- lumbar/sacral

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9
Q

The 2 observable enlargements of the spinal cord mark what?

A

mark the areas of the spinal cord that contain the neurons concerned with the upper and lower extremities, respectfully

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10
Q

Rostrally, the spinal cord is continuous with what part of the brainstem?

A

medulla oblongata

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11
Q

Caudally, the spinal cord tapers into what structure?

A

conus medullaris

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12
Q

The dorsal and ventral roots of the lower lumbar and sacral segments continue caudally to exit where?

A

exit through their appropriate intervertebral foramina

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13
Q

What makes the dorsal and ventral roots so long?

A

due to the differential growth of the spinal cord versus the spine

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14
Q

The collection of these long dorsal and ventral roots is known as?

A

cauda equina

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15
Q

What are the three layers of meninges that cover the spinal cord?
–> these coverings of the spinal cord vary somewhat to that surrounding the brain

A

1) dura mater
2) arachnoid
3) pia

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16
Q

Which layer of the spinal cord consists only of a meningeal layer?

A

Dura mater

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17
Q

The periosteal layer ends where?

A

foramen magnum

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18
Q

The epidural space is filled with what?

A

fat

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19
Q

The arachnoid mater acts as the limiting component to contain what substance?

A

CSF

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20
Q

When does the CSF get into the subarachnoid space of the spinal cord?

A

after leaving the foramina of Luschka and Magendie

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21
Q

Since the spinal cord ends at the level of L1-L2, that leaves a large pocket of subarachnoid space below the caudal tip of the cord….this space is known as what?

A

lumbar cistern

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22
Q

In what space is it safe to perform lumbar punctures (spinal tap)?

A

lumbar cistern - subarachnoid space below the caudal tip of the cord

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23
Q

What are the 2 components of the pia mater?

A

1) pia intima

2) denticulate ligaments

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24
Q

Which component of the pia mater is adhered directly to the spinal cord, much the same as with the brain?

A

pia intima

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25
Q

Extensions that protrude from the lateral sides of the cord and pierce the arachnoid to attach to the dura mater are called what?

A

denticulate ligaments

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26
Q

What is the function of the denticulate ligaments?

A

help anchor and stabilize the spinal cord in the vertebral canal

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27
Q

At the caudal end of conus medullaris, what ligament extends to anchor the spinal cord?

A

filum terminale

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28
Q

What is the filum terminale made up of ?

A
  • pia
  • glial elements
  • some remnants of coccygeal neuronal elements
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29
Q

What is the filum terminale termed, as it extends through and becomes encased with the dura mater attached to the coccyx?

A

coccygeal (sacral) ligament

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30
Q

What is the function of the coccygeal (sacral) ligament?

A

anchors the end of the cord in the spinal canal

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31
Q

Why is it safe to perform a lumbar puncture (spinal tap) in the lumbar cistern?

A

At the level of the lumbar cistern the nerve roots are suspended in CSF and therefore float away from the pressure of the needle.

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32
Q

What are the 4 segments of embryological segmental organization? (similar to segmental development of the spinal cord)

A
  • somites
  • dermatomes
  • myotomes
  • sclerotomes
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33
Q

How many pairs of spinal nerves are there?

A

31 (32) nerves

  • 8 cervical
  • 12 thoracic
  • 5 lumbar
  • 5 sacral
  • 1 (2) coccygeal
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34
Q

During development of the cord, what happens to the segmental arrangement of the spinal cord?

A

the segmental arrangement of the spinal cord gets obscured

35
Q

What are the 2 subdivisions of the spinal cord and CNS?

A

gray matter and white matter

36
Q

What is the central “butterfly” shaped area that consists of neuron cell bodies and glial cells?

A

gray matter

37
Q

What is the area surrounding the gray matter and contains myelinated axons?

A

white matter

38
Q

Which subdivision of the spinal cord contains both ascending and descending fiber tracts or pathways?

A

white matter

39
Q

The ascending and descending fiber tracts of the white matter of the spinal cord can be divided into what three general funiculi?

A
  • dorsal (posterior) funiculus
  • lateral funiculus
  • ventral (anterior) funiculus
40
Q

What is the general term for an area of white matter?

A

funiculus

41
Q

Gray matter is composed of what?

A

nerve cell bodies and their dendritic processes, and glial cells

42
Q

The lateral horn present from segments S1-S3 of the spinal cord is the location of what type of neurons?

A

preganglionic parasympathetic neurons for the lower parts of the body

43
Q

The lateral horn present from segments T1-L2 of the spinal cord is the location for what type of neurons?

A

preganglionic sympathetic neurons

44
Q

Gray matter is divided into various nuclei or divisions. This is referred to as what?

A

Lamina of Rexed

45
Q

The substantia gelatinosa of the dorsal horn is given what roman numeral (Lamina of rexed)?

A

Lamina II

46
Q

The dorsolateral tract of Lissauer is known as what?

A

Lissauer’s tract

47
Q

The nucleus proprius of the dorsal horn is given what roman numeral (Lamina of rexed)?

A

Lamina III, IV

48
Q

The dorsal nucleus of Clarke (segmental levels T2-L2) is given what roman numeral (Lamina of rexed)?

A

Lamina VII, in part

49
Q

The dorsal nucleus of Clarke is made primarily of what?

A

interneurons

50
Q

The intermediolateral cell column or lateral horn (segmental levels C8/T1 - L2; S1-S3) is given what roman numeral (Lamina of rexed)?

A

Lamina IX

51
Q

The ventral horn of the spinal cord is given what roman numeral (Lamina of rexed)?

A

Lamina IX

52
Q

The ventral horn is made primarily of what?

A

lower motor neurons that innervate extrafusal fibers

53
Q

The dorsal horn of the spinal cord receives what kind of information?

A

incoming sensory information

54
Q

What type of fibers enter the dorsal horn more medially, where the spinal cord is myelinated?

A

large diameter, heavily myelinated (Ia/b, A-alpha, II) fibers coming from encapsulated nerve endings

55
Q

What type of fibers enter the dorsal horn more laterally?

A

small diameter, non-myelinated C fibers and A-delta fibers coming from free nerve endings

56
Q

What two fiber types enter the spinal cord at Lissauer’s tract?

A

Fibers A-delta and C

57
Q

Lissauer’s tract contains axons that carry what kind of information into the dorsal horn of the spinal cord?

A

pain and temperature information

58
Q

The ventral horn of the spinal cord contains what kind of neurons?

A

lower motor neurons

59
Q

What are the two types of lower motor neurons (LMN) found in the ventral horn?

A
  • alpha-motor neurons

- gamma-motor neurons

60
Q

The neurons situated most medially in the ventral horn innervate what part of the body?

A

axial musculature (trunk, neck, etc.)

61
Q

The neurons situated most laterally in the ventral horn innervate what part of the body?

A

the muscles of the extremities

62
Q

The lower motor neurons situated posteriorly in the ventral horn are concerned with what muscles?

A

muscles of flexion

63
Q

The lower motor neurons situated anteriorly in the ventral horn are concerned with what muscles?

A

muscles of extension

64
Q

What regions of the spinal cord are concerned with the extremities?

A

lumbar and cervical spine

65
Q

What region of the spinal cord is NOT concerned with the extremities?

A

Thoracic spine

66
Q

What forms the spinal nerve?

A

the merging of the dorsal and ventral roots away from the spinal cord

67
Q

Prior to the merging of the dorsal and ventral roots, the dorsal root is entirely ________ and the ventral root is entirely _______.

A

dorsal –> sensory

ventral –> motor

68
Q

Once the merging of the dorsal and ventral roots occurs, the spinal nerve becomes what kind of nerve?

A

mixed nerve – has both motor and sensory components

69
Q

Each spinal nerve then branches into a number of branches to reach what?

A

its specific dermatomal segment or muscle of innervation

70
Q

What is associated with the spinal nerves at spinal cord levels T1-L2 is a series of what?

A

autonomic ganglia

71
Q

Autonomic ganglia are the location of what?

A

the postganglionic cell bodies for the sympathetic nervous system

72
Q

The preganglionic cell bodies are located where?

A

in the lateral horn in the spinal cord (intermediolateral) cell column

73
Q

What are specific, stereotyped motor responses to an adequate (appropriate) stimulus?

A

reflexes

74
Q

Reflexes require a series of structures consisting of a minimum of what four components?

A
  • receptor
  • afferent limb
  • efferent limb
  • effector organ
75
Q

A stretch reflex or deep tendon reflex (DTR) are also classified as what?

A

myostatic or monosynaptic

76
Q

What is an example of a deep tendon reflex (DTR)?

A

patellar ligament or knee jerk

77
Q

A deep tendon reflex demonstrates what principle?

A

autogenic facilitation with a small amount of reciprocal inhibition

78
Q

What is autogenic inhibition?

A

When the Golgi tendon organ (GTO) detects an increased tension while the muscle is contracting, the stimulus generates an inhibitory influence to the alpha motor neurons that are driving the contracting muscle. The muscle can now relax, releasing the tension.

79
Q

What is reciprocal facilitation?

A

Through the interneuronal pool, the antagonistic muscle can be activated to facilitate the release of tension

80
Q

What are the names of two complex reflexes? They involve more than just two neurons and the reciprocal inhibition of the antagonist/opposing muscle must occur.

A
  • Flexor Withdrawal Reflex

- Crossed Extension Reflex

81
Q

What is being inhibited during reciprocal inhibition?

A

antagonistic muscle

82
Q

What is being inhibited during recurrent inhibition?

A

same muscle and synergists

83
Q

What is being inhibited during non-reciprocal inhibition?

A

inhibits agonists, synergists and antagonists (coordination of various movements)

84
Q

What does segmental loss include and NOT include?

A

Include: the structures that are present at the specific segmental level – gray matter areas of the cord and to some extent the dorsal and ventral root components that are bringing in sensory information and/or sending out motor information
NOT include: the additional involvement of ascending and descending white matter pathways that are also involved