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NEUROANATOMY > (4) Development of CNS > Flashcards

(4) Development of CNS Flashcards

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1
Q

when does the nervous system arise

A

3rd week of life

  • when 3 principal layers are being generated by process of gastrulation
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2
Q

what are the 3 principal layers of the nervous sytem

A

ectoderm

medoderm

endoderm

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3
Q

what happens during gastrulation?

A
  • outer cells (epiblast) of embryo detach, migrate through primitive streak (groove) –> mesoderm and ectoderm are generated
  • remaining outside cells (epiblast) form ectoderm, from which NS develops. Later becomes epidermis
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4
Q

what happens at the beginning of the 3rd week of development to the ectoderm layer

A

in response to signals from midline tissues (notochord and prechordal mesoderm)

the ectoderm layer begins to thick and form neural plate

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5
Q

what do the cells of the neural plate do? (2 things)

A
  • invaginate and form canal (basis of NS)

- make up neuroectoderm and their induction represents the initial event of neurulation

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6
Q

what is neurulation

A

formation of the nervous system

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7
Q

in which way does the NS mature?

A

top to bottom

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8
Q

the CNS begins initially from….

A

uniform sheet of cells= neuroepitheliu m

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9
Q

when is the neural plate formed and how

A

3rd week of development

  • longitudinal band of ectoderm thickens to form the plate
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10
Q

how is the neural groove formed

A

neural plate folds inwards forming neural groove, flanked by neural folds

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11
Q

how is neural tube formed

A

as neural groove deepens, the folds move medially and begin to fuse forming the neural tube

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12
Q

what is the function of notochord?

A

instruct NS to become ventral

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13
Q

what do somites give rise to

A

give rise to skeleton, skin, and specialized cells called melanocytes

– they are called dermomyotome

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14
Q

rostral vs caudal

A

rostral= top/upper

caudal= bottom/lower

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15
Q

cephalic and caudal ends of neural tube comminicate with…

A

until the fusion is complete, they communicate with amniotic cavity by way of cranial (anterior) and caudal (posterior) neuropores

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16
Q

what happens at day 25

A

closure of cranial neuropore

18-20 somites

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17
Q

what happens at day 27

A

closure of caudal neuropore

25 somites

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18
Q

close of neural tube sensitive to… (2)

A
  • environmental agents
  • aberrant gene activity

failure of proper closure leads to neural tube defects

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19
Q

neural tube separating from the ectoderm

A

as the tube closes (fusion occuring rostrally and caudally), it separates from overlying ectoderm

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20
Q

notochord involved in … and becomes

A

it is the transient axial mesodermal structure

  • involved in ventral patterning of NS
  • becomes incorporate in developing intervertebral disks of the skeleton
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21
Q

mesoderm-derived somites will form…

A

most of the vertebral column and segmental units of muscle (myotomes) and dermis (dermatome)

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22
Q

what happens at day 24 and 26

A

24: tube is closed at rostral end
26: closed at caudal end, local enlargements (primary vesicles) are apparent

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23
Q

3 primary vesicles

A

prosencephalon
mesencephalon
rhombencephalon

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24
Q

in early development, 2 types of tissues

A

epithelium (have basement membrane)

mesenchyme

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25
what does the sulcus limitans do during closing of neural tube
separates dorsal and ventral tubes
26
neural tube defects frequency (live births)
occurs in 1 per 1000 live births
27
3 types of neural tube defects
cranioarchischisis anencephaly spina bifida
28
cranioarchischisis
- open spinal cord and spine - CNS is abnormally open on dorsal surface - complete failure neural tube fusion
29
anencephaly
- failure rostral end of neural tube to close | - fetus born no/reduced head
30
spina bifida
- failure of caudal end of neural tube to close - caudal walls are continuous with skin of the back, the cord and meninges are displaced into a saclike cavity on back - vertebrate fail to form over lesion - can be corrected by surgery
31
how does a primary vesicle form a secondary vesiscle
have specializations of primary vesicles to form secondary vesicles
32
cephalic and cervical flexure
- pockets of space Cephalic= anterior, between mesencephalon and rhombencephalon - secondary: between mesencephalon and metecephalon Cervical= between rhombencephalon and spinal cord - secondary: between myelencephalon and spinal cord
33
prosencephalon secondary vesicles
prosencephalon= forebrain - Telencephalon - Diencephalon
34
Derivative of telencephalon
cerebrum
35
derivatives of diencephalon (4)
thalamus hypothalamus retina other midbrain structures
36
secondary vesicles of mesencephalon
(midbrain) - secondary vesicles= mesencephalon
37
derivative of mesencephalon
midbrain
38
rhombencephalon secondary vesicles
(hindbrain) - Metencephalon - Myelencephalon
39
Metencephalon derivatives (2)
pons | cerebellum
40
myelencephalon derivative
medulla
41
list 5 secondary vesicles
``` telencephalon diencephalon mesencephalon metencephalon myelencephalon ```
42
fusion between diencephalon and telencephalon
part of cortical development - rapid expansion of cerebral hemispheres in 2nd month, results in downward folding of basal ganglia - by 3rd month, telencephalon and diencephalon have fused
43
development of ventricular system
as each cerebral hemisphere grows in a C-shaped manner, so does its lateral ventricle
44
flexures forming in ventricular system
as NS grows, spaces get trapped inside growing brai and get different parts of ventricular system - ex: lateral ventricle, 3rd ventricle
45
choroid plexus function
- regulates fluid in ventricular system - continuation of blood supply in brain - initially start as blood vessels, then start making choroid plexus
46
week 3 major developments (4)
- neural groove and folds - 3 primary vesicles visible - cervical and cephalic flexures - motor neurons appear
47
week 3 malformations
neural tube defects
48
week 4 major developments (6)
- neural tube starts to close (day 22) - rostral end of tube closes (day 24) - caudal end of tube closes (day 26) - neural crest cells begin to migrate - secondary neurulation starts - motor nerves emerge
49
week 4 malformations (2)
- neural tube defects | - holoprosencephaly
50
week 5 major developments (8)
- optic vesicle, pontine flexure - 5 secondary vesicles visible - sulcus limitans, sensory ganglia - sensory nerves grow into CNS - rhombic lips - basal ganglia begin - thalamus, hypothalamus begin - autonomic ganglia, lens, cochlea start
51
week 5 malformations (2)
holoprosencephaly sacral cord abnormalities
52
week 6-7 major developments (6)
- telencephalon enlarged - basal ganglia prominent - secondary neurulation complete - cerebellum and optic nerve begin - choroid plexus - insula
53
week 8-12 major developments (5)
- neural proliferation and migration - cerebral and cerebellar cortex begin - anterior commissure, optic chiasm - internal capsule - reflexes appear
54
week 8-12 malformations
migration/proliferation problems e.g. abnormal cortex/gyri
55
week 12-16 major developments (3)
- neuronal proliferation and migration - glial differentiation - corpus callosum
56
week 12-16 malformations
migration/proliferation problems e.g. abnormal cortex/gyri
57
week 16-40 major developments (4)
- neuronal migration - cortical sulci - glial proliferation, some myelination - synapse formation
58
week 16-40 malformations
- hemmorrhage other destructive events
59
neurocrest arises between
ectoderm and neuroectoderm
60
neural crest cells
as neural tube separates from ectoderm, it leaves behind a group of cells that were at the crest of each neural fold
61
where are cells born?
at the junction and migrate
62
neural crest cells migrate and give rise to... (4)
- sensory neurons (dorsal root ganglia of spinal nerves, some cranial nerves) - all post-ganglionic neurons of ANS - the adrenal medulla - Schwann cells
63
major difference between cranial and trunk neural crest cells is...
- cranial neural crest cells have ability to form cartilage and bone
64
sulcus limitans divides...
developing neural tube into posterior alar plate - and anterior basal plate that will give rise to sensory and motor areas of spinal cord and brainstem

NEUROANATOMY (7 decks)

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