Structure and fx of Spinal cord Flashcards

1
Q

What is at bottom end of Spinal cord?

A

Narrows at L1 to form conus medullar is, and then caudal equine in lumbar cistern

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2
Q

Where does spinal cord start and end?

A

Cranial border of atlas to L1

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3
Q

What is the lumbar cistern?

A

contains auda equina (Lumbar and sacral dorsal and ventral roots)
In Lumbar cistern

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4
Q

What surrounds the spinal cord?

A

The meninges are continuous, even as spinal cord descends within vertebral column

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5
Q

Why do you do a lumber puncture low down?

A

below L1 in caudal equine area, so nerves can float out of the way, and spinal cord is not damaged

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6
Q

What are the 4 sections of the spinal cord

A

Cervical
Thoracis
Lumbar
Sacral

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7
Q

What does the Ventral root of a spinal nerve do?

A

Ventral root: efferent

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8
Q

How many paired spinal nerves are there?

A

31

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9
Q

How many cervical nerve pairs are there

A

8

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10
Q

How many thoracic nerve pairs

A

12

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11
Q

How many lumbar nerve pairs

A

5

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12
Q

How many scacral nerve pairs?

A

5

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13
Q

How many coccygeal nerves?

A

1

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14
Q

Where do C1 and C8 nerves come out?

A

C1 nerve comes out ABOVE C1 vertebra, below foramen magnum, C8 comes out below C8

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15
Q

Where are “conus medullaris is” and filum terminale externum”

A

“conus medullaris” end of spinal cord
hilum terminale externum” end of dural sac?

filum terminale internum: upper three quarters of the filum; covered by the spinal dura and arachnoid meninges. filum terminale externum: lower quarter of the filum; fuses with the investing dura mater and continues inferiorly to attach to the dorsal coccyx

The filum terminale (FT) is a fibrous band that extends from the conus medullaris to the periosteum of the coccyx, and its functions are to fixate, stabilize, and buffer the distal spinal cord from normal and abnormal cephalic and caudal traction.

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16
Q

What does the Ventral root of a spinal nerve do?

A

Ventral root: efferent

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17
Q

What are the spinal nerves for?

A

Connect periphery and spinal cord

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18
Q

What is the dorsal column pathway? (overview)

A

Describes how a sensation passes up the spinal cord, crosses in the medulla and then connects to somatosensory centre in the cortex via 3 neurons and various junctions

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19
Q

What is the internal structure of the spinal cord?

A

Inner core, grey matter
- Neuronal cell bodies
- H shaped
- Ventral, lateral and dorsal horns

Outer, white matter
- Myelinated axons
- White columns/tracts/funiculi

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20
Q

Where in the spinal cord is grey matter expanded?

A

Note expanded grey matter at levels that supply the limbs

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21
Q

What does the dorsal root of a spinal nerve do?

A

Dorsal root: afferent

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22
Q

How is the grey matter organised in the dorsal horn?

A

Dorsal horn - Neurons receiving sensory input

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23
Q

How is the grey matter organised in the lateral horn?

A

Lateral horn - Preganglionic sympathetic neurons

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24
Q

How is the grey matter organised in the ventral horn?

A

ventral horn - Motor neurons
(Also interneurons between/within levels)

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25
Q

what are laminae?

A

Layers of neurons in grey matter are called laminae

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26
Q

How is white matter organised in the spinal cord?

A

Myelinated axons
Run in bundles in specific tracts

Many tracts are named according to cell body of origin and where the axon terminates
Helps to aid learning of the different tracts

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27
Q

What does the Ventral root of a spinal nerve do?

A

Ventral root: efferent

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28
Q

How is sensations carried to brain?

A

Sensation is carried to the brain: afferent tracts

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29
Q

How are sensations carried?

A

Sensation is carried to the brain: afferent tracts
Tracts to and from the brain are crossed:
R side of brain controls L side of body

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30
Q

How are motor commands carried?

A

Motor commands come from the brain: efferent tracts
Tracts to and from the brain are crossed:
R side of brain controls L side of body

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31
Q

Which columns carry ascending and descending tracts?
Dorsal:
Lateral:
Ventral:

A

Dorsal column contains ascending tracts
Lateral column contains descending and ascending tracts
Ventral column contains mainly descending tracts

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32
Q

Which columns carry ascending and descending tracts?
Dorsal:
Lateral:
Ventral:

A

Dorsal column contains ascending tracts
Lateral column contains descending and ascending tracts
Ventral column contains mainly descending tracts

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33
Q

Do messages go all the way to brain directly from body?

A

ascending tract nerves run in 3 order circuits

34
Q

What is “proprioceptive?”

A

Information from within the body: proprioceptive

35
Q

what is exteroceptive?

A

Information from outside the body: exteroceptive

36
Q

What do ascending tracts do?

A

Carry sensory information from periphery to brain

37
Q

What do Dorsal columns carry?
a pain
b temperature
c light touch
d proprioception?

A

Dorsal columns: proprioception/light touch

38
Q

What do spinocerebellar tracts carry?
a pain
b temperature
c light touch
d proprioception?

A

Spinocerebellar tracts: proprioception

39
Q

What do spinothalamic tracts carry?
a pain
b temperature
c light touch
d proprioception?

A

Spinothalamic tracts: pain/temperature

40
Q

What structure do nerves from the arm form?

A

Nerves from arm form cuneate fascilicus (Lateral)

41
Q

What structure do nerves from leg form?

A

Nerves from leg form gracile fascilicus (medial)

42
Q

(Dorsal column) what is the gracile fascilicus?
is it medial or lateral?

A

Nerves from leg form gracile fascilicus (medial)

43
Q

what is the gracile fascilicus?
is it medial or lateral?

A

Nerves from leg form gracile fascilicus (medial)

44
Q

In the dorsal column first order neuron enters spinal cord through _______?

A

First order neuron enters spinal cord through dorsal root (tract of Lissauer)

45
Q

In dorsal columns, Myelinated axons ascend ______ (opposite/same) side of cord?

A

Myelinated axons ascend same side of cord

46
Q

Describe the three neuron “steps” of the dorsal column pathway?

A

First order neuron synapses with 2nd order neuron in nucleus cuneatus (or nucleus gracilis in medulla)

2nd order neuron crosses midline in medulla of brain stem to form medial lemniscus

Ascends to thalamus to synapse with 3rd order neuron

Travels to somatosensory cortex

47
Q

whats ataxia?

A

Ataxia is a term for a group of disorders that affect co-ordination, balance and speech. Any part of the body can be affected, but people with ataxia often have difficulties with: balance and walking.

48
Q

what does the dorsal column do?

A

The dorsal column, also known as the dorsal column medial lemniscus pathway, deals with the conscious appreciation of fine touch, 2-point discrimination, conscious proprioception, and vibration sensations from the body; sparing the head.

49
Q

what happens when there is one sided damage to the dorsal column?

A

Disruption in pathway leads to unilateral loss of proprioception/VS/discriminative touch

50
Q

if both sides of the dorsal column are damaged what clinical result occurs?

A

Bilateral dorsal column loss leads to severe ataxia

51
Q

what diseases can bilaterally damage the dorsal column?

A

Possible causes: Multiple sclerosis, B12 deficiency

52
Q

Pt presents with unilateral loss of proprioception
vibration sensation, discriminative touch, what could be the cause?

A

Disruption in dorsal column pathway leads to unilateral loss of proprioception
vibration sensation, discriminative touch (2 point distinguishing?)

53
Q

what is discriminative touch?
what carries it?

A

Dorsal column
Fine touch (or discriminative touch) is a sensory modality that allows a subject to sense and localize touch. The form of touch where localization is not possible is known as crude touch.

54
Q

What do spinothalamic tracts carry?

A

Sensory
unconscious proprioception and smooth motor control

nociceptive, temperature, crude touch, and pressure from our skin to the somatosensory area of the thalamus

55
Q

What is “nociceptive?”

A

Nociceptors are sensory receptors that detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue. Nociceptors are free (bare) nerve endings found in the skin muscle, joints, bone and viscera.

56
Q

How many neurons in the spinothalamic circuit?

A

2
1st order neuron enters through dorsal root (tract of Lissauer)

Synapses with second order neuron

Crosses midline at level of entry

Myelinated fibres ascend up anterior/lateral spinothalamic tract

57
Q

do spinothalamic tracts cross at medulla or at level of entry?

A

Crosses midline at level of entry

58
Q

what is the tract of lissauer?

A
59
Q

What is responsible for the transmission of pain, temperature, and crude touch to the somatosensory region of the thalamus?

A

spinothalamic tract, an ascending pathway of the spinal cord

60
Q

What are these two fissures/sulci called?

A

Anterior (ventral) median fissure
posterior (dorsal) median sulcus

61
Q

which nerves pass through sacral hiatus?

A

S5 (x2)
coccygeal

62
Q

where does hilum terminale attach and what does it do?

A

It extends from the conus medullaris and descends among the nerve roots of the cauda equina to attach to the dorsum of the coccyx, acting as an anchor for the spinal cord within the vertebral canal.

63
Q

label these spinal meningeal layers

A

spinal pia mater
spinal arachnoid mater
spinal dura mater

64
Q

label:
ventral
dorsal
lateral

A
65
Q

What do the descending tracts of the spinal cord do?

A

Innervate motor neurones

66
Q

what do dorsal root ganglions at spinal cord carry?

A

sensory afferent fibres from body organs/muscles

67
Q

What do ventral roots fo spinal cord carry?

A

Motor fibres, efferent

68
Q

What is the central commissure of the spinal cord?

A

The gray matter is subdivided into the gray commissure, which is the strip connecting the two halves of the spinal cord that surrounds the central canal (“H”)

69
Q

What are the dorsal and ventral horns?

A

The “top and bottom” of the “H” of grey matter in spinal cord

70
Q

What do ventral horns contain?

A

cell bodies of motor neurons

71
Q

What do dorsal horns contain?

A

Dorsal horns contain neuronal cell bodies that process information received from sensory fibers, entering the spinal cord from the dorsal roots and dorsal rootlets

72
Q

Where are upper motor neurons found?

A

upper motor neurons are found inside the cerebral cortex and various nuclei of the brainstem,

73
Q

Where are lower motor neurons found?

A

lower motor neurons are found inside the brainstem or the ventral horn of the spinal cord

74
Q

How are muscles of the body innervated?

A

From the ventral horns, axons from lower motor neurons leave the spinal cord through the ventral roots and travel within peripheral nerves to innervate the skeletal muscles of the body.

75
Q

How does the corticospinal tract run?

A

From the primary motor CORTEX to spinal cord, to innervate voluntary movements of trunk and limbs

76
Q

How do the upper motor neurones run in corticospinal tract?

A

The cell bodies of the first-order neurons of this pathway lie in the primary motor cortex. The axons then descend via the
-corona radiata, through the -internal capsule, the
-cerebral peduncle of the midbrain, and the
-ventral aspect of the pons to reach the
-ventral aspect of the medulla.

77
Q

SLIDE 20

A
78
Q

-
-

A

Dorsal columns: light touch/proprioception

Spinothalamic tracts: pain/temperature

Spinocerebellar tracts: unconscious proprioception

79
Q

Dorsal columns:
Spinothalamic tracts:
Spinocerebellar tracts:

A

Dorsal columns: light touch/proprioception

Spinothalamic tracts: pain/temperature

Spinocerebellar tracts: unconscious proprioception

80
Q

What do descending tracts do?

A

Involved in control of movement

Voluntary control of movement: corticospinal tract=pyramidal tract

Involuntary control of movement:
Extrapyramidal tracts

81
Q

Are Extrapyramidal tracts for voluntary or involuntary movement?

A

Involuntary control of movement:
Extrapyramidal tracts

82
Q
A

Voluntary control of movement: corticospinal tract=pyramidal tract