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5 - Neuro > Neuro embryology > Flashcards

Neuro embryology Flashcards

1
Q

Which layer of the trilaminar disc gives rise to the nervous system?

A

Ectoderm- thickens to form a neural plate

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2
Q

How does the notochord form and what does it do?

A

Migration of pre-notochordal cells into the primitive pit gives rise to the notochord in the midline. They initiate the thickening of the ectoderm to form a neural plate which will go on to form the neural tube.

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3
Q

How is the neural tube formed?

A

Folding of neural plate at day 19.

  • central neural groove forms in the midline
  • takes about 10 days
  • elevation of the edges followed by fusion at the midline
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4
Q

Where do you find the future cervical region?

A

Where fusion of the tube begins.

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5
Q

Why do neural tube defects occur?

A

Due to defects in closure of the neuropores

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6
Q

When do the neuropores fuse?

A 
Anterior = day 25
Posterior = day 28
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7
Q

Describe spina bifida

A

Failure of closure at the caudal end of the neural tube- leads to incomplete development of the vertebral arches

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8
Q

What are the different types of spina bifida?

A

Spina bifida occulta

Spina bifida cystica

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9
Q

Describe spina bifida cystica

A

NT fails to close, vertebral arched fail to form and the neural tissue is exposed- spinal cord and neural tissue can herniate into back region, causing a cyst- usually accompanied by hydrocephalus, does not cause it though

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10
Q

Where can spina bifida cystica occur?

A

Anywhere along the spinal cord- most common in the lumbosacral region

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11
Q

Why can cognitive delays occur in spina bifida cystica?

A

Due to hydrocephalus hat sometimes accompanies SB cystica- not directly due to spina bifida

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12
Q

Describe meningocoele

A

Meninges herniate through the unfused regions of the spine

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13
Q

Describe myelomeningocoele

A

Spinal cord and meninges herniate though the unfused regions of the lumbar spine

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14
Q

Describe spina bifida occulta

A

Not as serious

  • defect of spinous processes but meninges are mostly enclosed in vertebrae
  • usually asymptomatic
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15
Q

Describe hydrocephalus

A 
Accumulation of CSF in ventricle or cavities of the brain
Leads to: increase ICP
head enlargement
convulsion
tunnel vision
mental disability
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16
Q

Describe anencphaly

A

NTD neural tube fails to close cranially leading to tissue degeneration and little/no formation of higher brain centres

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17
Q

What are the characteristics of anencephaly?

A

Complete absence of cranial structures- condition is incompatible with life- babies that make it to term will often be stillborn

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18
Q

Describe rachischisis

A

Failure of neural fold elevation. Most severe NTD

  • splayed nervous tissue
  • incompatible with life
  • can occur with anencephaly
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19
Q

How can NTD be diagnosed?

A

Raise serum alpha-fetoprotein
- NTD and failure of closure of abdominal structures
Ultrasound

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20
Q

What can reduce the incidence of NTDs?

A

Mother taking folic acid supplements

- 3 months pre-conception and for the 1st trimester

21
Q

What does the neural tube give rise to?

A

Spinal cord

22
Q

Describe how the vertebral column and spinal cord develop together

A

3 months - same length
Spinal cord stops growing at this point
VC grows longer and faster than the SC
Roots of nerve below L1/L2 must elongate so they can exit through their intervertebral foramen
Gives rise to the cauda equina
Pia mater surrounding spinal cord projects down and attaches the conus medullaris to the back of the coccyx
Called the filum terminale and stabilises the spinal cord.

23
Q

Where do lumbar punctures usually occur?

A

At or below L4/L5
Will not damage the spinal cord
Conus medullaris terminates at L2
Lumbar fluid is drawn form the lumbar cistern

24
Q

What does the lumbar cistern contain?

A

Filum terminales

Nerve roots of cauda equina

25
Q

What are the three primary vesicles of the brain?

A

Prosencephalon
Mesencephalon
Rhombencephalon

26
Q

What do each of the divisions represent?

A 
Prosencephalon = forebrain
Mesencephalon = midbrain
Rhombencephalon = hindbrain
27
Q

What are the five secondary brain vesicles?

A 
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
28
Q

What are the derivations of the telencephalon?

A

Cerebral hemispheres

29
Q

What are the derivations of the diencephalon?

A

Thalamus

30
Q

What are the derivations of theMesencephalon?

A

Midbrain

31
Q

What are the derivations of the metencephalon?

A

Pons and cerebellum

32
Q

What are the derivations of the myelencephalon?

A

Medulla oblongata

33
Q

What are the flexures of the brain?

A

Cervical flexure and cephalic flexure

34
Q

Where do each of the flexures occur?

A 
Cervical = spinal-hindbrain junction
Cephalic = midbrain region
35
Q

What is the significance of the flexures?

A

Neuroaxis does not remain straight

36
Q

Describe the ventricular system

A 
Four in total
- 2 lateral
- third ventricle
- fourth ventricle
Are continuousContain CSF
37
Q

Main function of ventricles?

A

bathe and cushion the brain

38
Q

What produces CSF?

A

Ependymal cells of the choroid plexus

39
Q

Describe the connections of the ventricular system

A

Lat. ventricle to 3rd ventricle via the intervertebral foramen
3rd to 4th ventricle via cerebral aqueduct
4th ventricle to subarachnoid space via median aperture and R and L lateral aperture via the cistern of the great cerebral vein.

40
Q

Hydrocephalus treatment?

A

Shunt to shunt the CSF from the ventricular system, usually to the peritoneal cavity

41
Q

Why does hydrocephalus commonly occur?

A

Blockage in the ventricular system

  • tumour
  • infection
42
Q

Describe neural crest cells

A 
Found at lat border of neuroectoderm
Are specially differentiated
Migrate to diff areas around the body
Undergo epithelial to mesenchymal transition
Form a wide variety of tissues
43
Q

Give some tissues in the nervous system which are derived from neural crest cells

A 
CN ganglia
Spinal root ganglia
Sympathetic and parasympathetic ganglia
Schwann cells
Glial cells
Leptomeninges
44
Q

Give some tissues in the head, neck and midline structures which are derived from neural crest cells

A

CT, bones of face and skull
Odontoblasts
Dermis of face and neck
C cells of thyroid gland

45
Q

Give some other tissues which are derived from neural crest cells

A

Conotruncal septum in the heart
Melanocytes
Adrenal medulla

46
Q

What is a particular characteristic of neural crest cells?

A

They are particularly vulnerable to environmental insult e.g. by alcohol. - effects on numerous tissues, yet only one component is damaged

47
Q

Describe Hirschprung’s disease

A

Congenital aganglionic megacolon- lack of parasympathetic ganglion in bowel wall- lack of function of small bowel as it cannot relax and let stool pass through, causing an obstruction

48
Q

Describe DiGeorge syndrome

A

Autosomal dominant disease due to deletion of part of chromosome 22
C - congential heart abnormalities
A - abnormal facies (abnormal distinct facial expressions)
T - Thymic hypoplasia (leads to immunodeficiency)
C - cleft palate
H - Hypocalcaemia due to hypoparathyroidism

5 - Neuro (17 decks)

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