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Year 2 - Nervous > Embryology > Flashcards

Embryology Flashcards

(67 cards)

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1
Q

What week does gastrulation occur and therefore what week does CNS begin to appear

A

3

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2
Q

Neural tube initially remains open at its anterior and posterior ends as what

A

Anterior and posterior neuropores

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3
Q

What week do the 3 primary brain vesicles form

A

4

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4
Q

What week do the 3 primary vesicles subdivide into 5 secondary vesicles

A

5

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5
Q

What flexure divides the mesencephalon and rhombencephalon

A

Cephalic

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6
Q

What flexure divides the rhombencephalon and spinal cord

A

Cervical

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7
Q

What flexure divides the metencephalon and myelencephalon

A

Pontine

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8
Q

What week does CSF formation begin

A

5

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9
Q

What do neural crest cells form

A

PNS neurons and glia

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10
Q

What week does cortical folding occur to form sulci and gyri

A

26

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11
Q

Name 3 neural tube defects (due to failure of neural tube to close)

A

Anencephaly/exencephaly
Encephalocele
Spina bifida

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12
Q

What causes anencephaly

+ what is the resulting damage

A

Failure of anterior neuropore to close

Skull fails to form, brain tissue degenerates

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13
Q

What is craniorachischisis

A

Failure of neural tube to close along entire neuroaxis

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14
Q

What causes encephalocele

+ what is it

A

Failure of anterior neural tube to close

Herniation of cerebral tissue through a defect in the skull

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15
Q

What causes spina bifida

A

Failure of caudal neural tube to close

Non-fusion of the vertebral arches

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16
Q

Name the 2 types of spina bifida

A

Spina bifida occulta

Spina bifida cystica

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17
Q

Name other congenital brain abnormalities

A

Lissencephaly - smooth brain (no gyri or sulci)

Polymicrogyria

Microcephaly

Agenesis corpus callosum

Porencephaly

Schizenecephaly

Diastematomyelia (split cord malformation)

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18
Q

When does neural tube fuse/close

-when does it begin + when is it completed by

A

Begins day 18 and complete by end of 4th week

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19
Q

When the 3 germ layers (ectoderm, mesoderm, endoderm) have formed, cells from primitive streak continue to sink down to form what

A

Notochord (solid tube of cells in the midline)

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20
Q

What does the notochord do

A

sends out signals to ectodermal cells in the midline, causing the cells there to thicken and influencing a neural plate to form

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21
Q

Neural plate eventually sinks down and forms a dip in the midline of the ectoderm layer then…

A

Surface ectoderm comes together centrally and encloses the neural tube

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22
Q

Name the 3 primary brain vesicles

A

forebrain/rosencephalon,

midbrain/mesencephalon,

hindbrain/rhombencephalon

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23
Q

Name the 5 secondary brain vesicles

A

Forebrain:
Telencephalon,
Diencephalon,

Midbrain:
Mesencephalon,

Hindbrain:
Metencephalon, Myelencephalon

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24
Q

Optic vesicles grow laterally from which brain vesicle of the neural tube

A

Diencephalon

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25
Optic vesicles eventually develop into what
Eyeballs
26
When the optic vesicles reach surface ectoderm, it sends signals to the surface ectoderm inducing what to happen
surface ectoderm to thicken --> forming the lens placode
27
Define placode
thickening of embryological tissue
28
Optic cup is connected to neural tube by what
Optic stalk (future CN II)
29
10th layer of retina is formed by inner or outer layer of optic cup Other 9 layers of the retina are formed by inner or outer layer of optic cup A potential space therefore sits between the inner 9 layers and the outer 10th layer which is important clinically because it gives rise to...
outer inner Diseases like retinal detachment
30
5 histological layers of the cornea
``` Epithelium Bowman's membrane Stroma Descemet's layer Endothelium ```
31
What type of epithelium covers the cornea
Stratified squamous non-keratinised
32
What is bowman's membrane
Basement membrane of corneal epithelium
33
What is the stroma of the cornea made of
REGULARLY ARRANGED COLLAGEN FIBRES --> making cornea TRANSPARENT
34
What is descemet's layer
Basement membrane of the endothelium
35
Endothelium v epithelium
Endothelium is just epithelium lining the inside of a surface
36
If cornea is avascular, where does it get its nutrition from
from AH and blood vessels at the side of it
37
Which of the 3 germ layers does the CNS develop from
Ectoderm
38
Telencephalon becomes the (3)
Cerebral hemispheres Hippocampus Basal ganglia
39
Metencephalon becomes the (2)
Cerebellum | Pons
40
Myelencephalon becomes the
medulla
41
Lumen of neural tube forms the
ventricular system
42
Name a genetic cause of hydrocephalus
Congenital aqueductal stenosis
43
Neural tube is lined with what epithelium
Pseudostratifed
44
Neural tube is initially a single layer of rapidly dividing neuroepithelial cells Neuroepithelium goes on to produces most cells of the CNS including... (4)
Neurons Astrocytes (glia) Oligodendrocytes (glia) Ependymal cells (glia)
45
Microglia ARE NOT derived from neuroepithelial cells, instead they're derived from...
MESENCHYMAL CELLS that migrate into CNS
46
Neural tube also forms non-neuronal cells such as (2)
Melanocytes | Adrenal medulla
47
Neural crest cells are derived from... and break away from it by undergoing a what transition
neural ectoderm epithelial to mesenchyme transition
48
Neural crest cells migrate through the neural tube to form things such as
DRG | Autonomic ganglia
49
Neural crest cells form the motor or sensory component of spinal nerves
sensory
50
Cortical folding (where the brain develops sulci and gyri) occurs at what week + purpose of this folding
26 Minimises brain volume and bring together brain regions that would otherwise be far apart
51
Describe spina bifida occulta (a type of spina bifida) - failure of what to fuse - usually occurs in which vertebral levels - symptoms/signs
Most common but most minor Failure of embryonic halves of vertebral arch to grow normally and fuse Occurs in L5 & L6 vertebrae No symptoms SIGN SOMETIMES - dimple in back with a bushy growth of hair
52
Spina bifida cystica is what
protrusion of spinal cord through the defect in the vertebral arches
53
3 subtypes of spina bifida cystica
Spina bifida with meningocele Spinda bifida with meningomyelocele Myeloschisis (most severe)
54
Prenatal diagnostic investigations of spina bifida (3)
Maternal blood screening Amniocentesis Ultrasound
55
How can maternal blood screening diagnose spina bifida
Neural tube defect would be indicated by HIGH ALPHA FETOPROTEIN (AFP) in blood
56
How early can spina bifida be detected in utero
16-20 wks
57
How can amniocentesis diagnose spina bifida
high levels of alpha fetoprotein (AFP) in amniotic fluid (foetal liver leaks into amniotic fluid)
58
Pregnant women are advised to take what to prevent neural tube defects
FOLIC ACID SUPPLEMENTS
59
Risk factors of neural tube defects
Genetic predisposition, e.g. abnormal fold acid metabolism Poor nutrition, e.g. too little folate, teratogens Environmental, e.g. hypothermia, toxic drugs
60
What is lissencephaly
'smooth brain' - no formation of gyri or sulci - -> severe mental impairment
61
What is polymicrogyria
excessive number of small gyri --> variable neuro problems
62
What is microcephaly
Head circumference smaller than usual | -usually have a small brain and intellectual disability
63
What isa genesis corpus callosum
Complete or partial absence of the corpus callosum
64
What is porencephaly
CSF FILLED CYSTS OR CAVITIES in the brain extremely rare
65
What is schizencephaly
Loss of brain tissue --> large clefts/spaces in brain often presents with seizures, mental retardation, hemiparesis
66
What is diastematomyelia
Split cord malformation | -spinal cord splits longitudinally into 2
67
Causes of brain defects
``` Genetic Infection - e.g. rubella Radiation Maternal alcohol abuse Drugs ```

Year 2 - Nervous (39 decks)

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