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Year 2- CNS > Nervous system Embryology and Congenital Malformations > Flashcards

Nervous system Embryology and Congenital Malformations Flashcards

1
Q

Which layer of the trilaminar disc forms the neural tube?

A

Ectoderm

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2
Q

In which week of development does the CNS start to develop?

A

Week 3

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3
Q

What is formed when there is thickening of the ectoderm anterior to the primitive node?

A

Neural plate

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4
Q

What is formed when the edges of the neural edges move upward?

A

Neural folds

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5
Q

What is formed when the neural folds grow so much and start to move towards each other and eventually fuse?

A

Neural tube

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6
Q

Fusion of the anterior and posterior ends of the neural tube is delayed. What does this form?

A

Anterior and posterior neuropore

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7
Q

When does the anterior neuropore close?

A

Approx. day 25

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8
Q

When does the posterior neuropore close?

A

Approx. day 27

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9
Q

Failure of the neural tube closing properly results in neural tube defects.

Name three of the most common neural tube defects?

A

Anencephaly
Encephalocele
Spina Bifida

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10
Q

Who is more likely to develop anencephaly- males or females?

A

Females 4x more likely

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11
Q

What happens in anencphaly?

A

Anterior neuropore fails to close meaning the skull fails for form.

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12
Q

The lack of skull in Anencephaly means tissue is in direct contact with amniotic fluid. What does this cause to happen?

A

Brain tissue degenerates

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13
Q

Is anencephaly compatible with life?

A

No

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14
Q

What happens in Encephalocoele?

A

Herniation of cerebral tissue through a defect in the skull

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15
Q

What causes encephalocoele?

A

Failure of closure of the rostral neural tube.

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16
Q

Which region is encephalocoele most common in?

A

Occipital region

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17
Q

How does encephalocoele affect the child?

A

Variable degree of neurological deficits, depending on which area of the brain is affected.

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18
Q

What causes spina bifida?

A

Defective closure of caudal neural tube

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19
Q

Which tissues are affected by spina bifida?

A

Tissues overlying the spinal cord

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20
Q

In all forms of spina bifida, there is a defect in what?

A

Vertebral arches

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21
Q

What is the most common form of spina bifida?

A

Spina bifida occulta

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22
Q

Which type of spina bifida is the mildest?

A

Spina bifida occulta

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23
Q

What causes spina bifida occulta?

A

Failure of embryotic halves of vertebral arch to grow and fuse

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24
Q

Which vertebrae are affected by spina bifida occulta?

A

L5/6

->extra lumbar vertebrae due to bones not fusing:) 10% of population have it

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25
Q

A lot of the time, people with spina bifida occulta will not realise they have it.
Occasionally, what can mark the site of non-fusion?

A

Small patch of hair

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26
Q

What is spina bifida cystica?

A

Protrusion of the spinal cord and/or meninges through a defect in the vertebral arches

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27
Q

Which type of spina bifida cystica is the rarest and mildest?

A

Spina bifida with meningocele

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28
Q

What happens in spina bifida with meningocele?

A

Protrusion of meninges and CBF

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29
Q

What happens in spina bifida with meningomyelocele?

A

Herniation of neural tissue or nerves in the fluid filled sac.

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30
Q

What can spina bifida with meningomyelocle cause?

A

Neurological deficiencies- loss of sensation, muscle paralysis- depends on affected area

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31
Q

What is spina bifida with meningomyelocle associated with?

A

Hydrocephalous (build up of fluid in the brain).

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32
Q

Which type of spina bifida is the most severe?

A

Myeloschisis.

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33
Q

What happens in myeloschisis?

A

Failure of neural tube closure-spinal cord appears to be flattened and has no overlying membrane meaning tissue is exposed to amniotic fluid.

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34
Q

What should pregnant women take to reduce risks of neural tube defects in their child?

A

Folic acid supplements

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35
Q

All pregnant women are offered maternal blood screening to check for AFP. What does a high level of AFP mean?

A

AFP produced in foetal liver. If there is a defect, it can leak into amniotic fluid and then into maternal blood.

36
Q

At which point in pregnancy is AFP best detected?

A

16-20 wks

37
Q

What can be used to determine if high AFP is coming from the foetus rather than the mother?

A

Amniocentesis

38
Q

What are some of the risk factors for neural tube defects?

A

Genetic predisposition
Nutrition
Environmental

39
Q

Just for you, describe which aspects in the diet can lead to increased risks of neural tube defects.

A

Low folate
High vitamin A

40
Q

Which drug can increase risks of neural tube defects?

A

Sodium valproate

41
Q

During week 4 of development, there is development of the three primary brain vesicles. Which name is given to the forebrain vesicle?

A

Prosencephalon

42
Q

During week 4 of development, there is development of the three primary brain vesicles. Which name is given to the midbrain vesicle?

A

Mesencephalon

43
Q

During week 4 of development, there is development of the three primary brain vesicles. Which name is given to the hindbrain vesicle?

A

Rhombencephalon

44
Q

The primary vesicles then split to form secondary vesicles. What does the prosencephalon divide to form?

A

Telencephalon
Diencephalon

45
Q

The primary vesicles then split to form secondary vesicles. What does the rhombencephalon divide to form?

A

Metencephalon
Myelencephalon

46
Q

What happens to the mesencephalon during the division of primary vesicles into secondary vesicles?

A

Remains as mesocephalon

47
Q

Between which parts of the brain does the cephalic flexure develop?

A

Between midbrain and hindbrain

(mesencephalon and rhombencephalon)

48
Q

Between which parts of the brain does the cervical flexure develop?

A

Hindbrain and spinal cord

49
Q

Where does the pontine flexure develop?

A

In the brain

50
Q

What does the telencephalon give rise to?

A

Cerebral hemispheres
Hippocampus
Basal ganglia

51
Q

What does the diencephalon give rise to?

A

Thalamus
Hypothalamus
Pituitary gland
Pineal

52
Q

What does the mesencephalon give rise to?

A

Superior and inferior colliculi

53
Q

What does the metencephalon (division of hindbrain) give rise to?

A

Cerebellum
Pons

54
Q

What does the myelencephalon (division of the hindbrain) give rise to?

A

Medulla

55
Q

Why does the brain have folds?

A

To save space

56
Q

Name the rare conditions where the brain is smooth and has no folds.

A

Lissencephaly

57
Q

What causes lissencephaly?

A

Defective neuronal migration

58
Q

Which condition occurs when there is an excessive number of small gyri?

A

Polymicrogyria

(think, poly=many, micro=small, gyria!)

59
Q

The lumen of the neural tube forms the ventricular system of the brain.

Which ventricle is formed from the telecephalon?

A

Lateral ventricles

60
Q

The lumen of the neural tube forms the ventricular system of the brain.

Which ventricle is formed from the diencephalon?

A

3rd ventricle

61
Q

The lumen of the neural tube forms the ventricular system of the brain.

Which ventricle is formed from the mesencephalon?

A

Cerebral aqueduct

62
Q

The lumen of the neural tube forms the ventricular system of the brain.

Which ventricle is formed from the metencephalon?

A

4th ventricle

63
Q

The lumen of the neural tube forms the ventricular system of the brain.

Which ventricle is formed from the myelecephalon?

A

Central canal

64
Q

In which week of development is CBF produced?

A

Week 5

65
Q

Where is CBF produced?

A

Choroid plexus in the 3rd and 4th ventricles

66
Q

What is hydrocephalous caused by?

A

Accumulation of CSF resulting in an enlarged brain and cranium

67
Q

What is frequently the cause of hydrocephalus?

A

Blocked cerebral aqueduct

68
Q

Which type of spina bifida is hydrocephalus associated with?

A

Spina bifida cystica

69
Q

What type of epithelium does the neural tube have?

A

Pseudostratified epithelium

70
Q

Neural tube produces most of the cells of the CNS.
Which cells don’t they produce?

A

Mesenchymal cells which are phagocytic cells

71
Q

What does the PNS develop from?

A

Neural crest cells

72
Q

Which type of nerve are spinal nerves?

A

Mixed- motor and sensory

73
Q

Now for some very rare congenital anomalies-
Microcephaly (small brain).
What causes microcephaly?

A

Genetics
Drugs
Zika virus infection

74
Q

Aegenesis of corpus callosum?

A

Corpus of callosum, which connects the two cerebral hemispheres is missing.

75
Q

Porencephaly?

A

Formation of CSF filled cysts or cavities within the brain

76
Q

What can cause porencephaly?

A

Postnasal stroke or infection

77
Q

Schizencephaly?

A

Large clefts or slits in the brain

78
Q

Why does schizencephaly occur?

A

Usually due to genetics or utero stroke or infection

79
Q

What happens in split cord malformation (diastematomyelia)?

A

Spinal cord splits longitudally into 2

80
Q

What can diastematomyelia cause?

A

Scoliosis

81
Q

Intellectual impairment is a much more common problem to do with the functioning of our CNS.

Give an example of intellectual impairment with is genetic.

A

Down’s syndrome

82
Q

What are some causes of intellectual impairment?

A

Genetic (Down’s)
Radiation
Infectious agents
Birth trauma

83
Q

What is the most common cause of intellectual impairment?

A

Maternal alcohol abuse

84
Q

When in development is the neural tube closed by?

A

End of week four

85
Q
A

Year 2- CNS (49 decks)

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