Embryology

Question 1

what are the three layers of the derm layers?

Answer 1

ectoderm
mesoderm
endoderm

Question 2

what layer of the term trilaminar plate forms the nervous system?

Answer 2

ectoderm

Question 3

what layer of the term trilaminar plate forms the bone?

Answer 3

mesoderm

Question 4

what layer of the term trilaminar plate forms the gut?

Answer 4

endoderm

Question 5

what layer of the term trilaminar plate forms the lungs?

Answer 5

endoderm

Question 6

what layer of the term trilaminar plate forms the epidermis ?

Answer 6

ectoderm

Question 7

what layer of the term trilaminar plate is in contact with the yolk sac?

Answer 7

endoderm

Question 8

at which week does the CNS start to appear?

Answer 8

3rd week

Question 9

what is formed from the thickening of the ectoderm anterior to the primitive node?

Answer 9

neural plate

Question 10

what causes the neural plate to form?

Answer 10

primitive node sends out signals

Question 11

what are the thickened edges of the neural plate called?

Answer 11

neural folds

Question 12

what day does the neural plate start to fold ?

Answer 12

day 20

Question 13

where is the first area the neural tube starts to fuse?

Answer 13

in the middle

Question 14

at what day does the anterior and posterior neuropore both close ?

Answer 14

day 27

Question 15

what neuropore closes first?

the anterior or posterior

Answer 15

the anterior closes first at day 25

the posterior closes at day 27

Question 16

what is another name for the anterior neuropore ?

Answer 16

the rostral

Question 17

before the neural tube closes, is it in contact with amniotic fluid ?

Answer 17

yes

Question 18

what is the depression down the neural tube called?

Answer 18

neural groove

Question 19

what shape do the cells in the neural groove change from and to ?

Answer 19

columnar -> wedge shaped

Question 20

what are the three main neural tube defects ?

Answer 20

Anencephaly
Encephalocoele
Spina bifida

Question 21

what defect occurs during anencephaly ?

Answer 21

failure of the anterior neuropore closure

Question 22

what would result in the anterior neuropore not closing?

Answer 22

the neural tube is in contact with the amniotic fluid so the skull and brain can’t form properly

Question 23

can’t people with anencephaly survive?

Answer 23

no

- usually still birth

Question 24

is anencephaly more common in males or females ?

Answer 24

x4 common in females

Question 25

what defect results in encephalocoele?

Answer 25

when the rostral neuropore doesn't close properly and cerebral tissue herniates through the skull defect

Question 26

in what areas is the skull defect most common in encephalocoele?

Answer 26

occipital and fronto-nasal area

Question 27

what common defects post birth does encephalocoele result in due to the areas of brain which is affected?

Answer 27

vision impairment and emotion and cognitive impairment

Question 28

what do the degree of neurological deficits depend on ?

Answer 28

- part of brain affected | - area of brain affected

Question 29

out of the three most known neural tube defects which one is most common?

Answer 29

spina bifida

Question 30

is anencephaly and encephalocoele common?

Answer 30

no they are rare

Question 31

what defect results in spina bifida ?

Answer 31

defect in the closure of the caudal (posterior) neuropore and the vertebral arches don't fuse

Question 32

are there different subtypes of spina bifida ?

Answer 32

yes three main subtypes

Question 33

what are the three sub types of spina bifida ?

Answer 33

meningocele meningomyelocle myeloschisis

Question 34

which of the three subtypes of spina bifida are most severe?

Answer 34

myeloschisis

Question 35

has the incidence of spina bifida been increasing or decreasing ?

Answer 35

decreasing

Question 36

state two reasons why spina bifida incidence is decreasing?

Answer 36

- folic acid supplements | - prenatal screening

Question 37

what is the rarest type of spina bifida ?

Answer 37

meningocele

Question 38

what three tests can be done prenatal to test for spina bifida ?

Answer 38

1. blood test for alpha fetoprotein (increased) 2. amniocentisis 3. ultrasound

Question 39

What three risk factors are there for neural tube defects?

Answer 39

1. genetic predisposition 2. nutritional 3. environmental

Question 40

how many primary vesicles are there?

Answer 40

3

Question 41

what are the three primary vesicles called?

Answer 41

prosencephalon mesencephalon rhombencephalon

Question 42

what week do the primary vesicles form?

Answer 42

4th week

Question 43

what week do the secondary vesicles form?

Answer 43

5th week

Question 44

what are the three flexures in the neural tube are there?

Answer 44

cephalic pontine cervical

Question 45

what structures does the cephalic flexure divide?

Answer 45

midbrain and hindbrain

Question 46

what structures does the pontine flexure divide?

Answer 46

the two vesicles in the hindbrain

Question 47

what structures does the cervical flexure divide?

Answer 47

the hindbrain and spinal cord

Question 48

what structures are formed from the telencephalon ?

Answer 48

cerebral hemispheres, hippocampus, basal ganglia

Question 49

what structures are formed from the diencephalon ?

Answer 49

thalamus hypothalamus pituitary gland pineal gland

Question 50

what structures are formed from the mesencephalon ?

Answer 50

superior and inferior colliculi

Question 51

what structures are formed from the metencephalon ?

Answer 51

cerebellum and pons

Question 52

what structures are formed from the myelencephalon ?

Answer 52

medulla

Question 53

what week does CSF start to be formed?

Answer 53

5th

Question 54

what produces CSF?

Answer 54

choroid plexus

Question 55

in which ventricle does the CSF drain into the subarachnoid space?

Answer 55

4th ventricle

Question 56

where does the CSF reabsorbed back into venous system ?

Answer 56

arachnoid villi

Question 57

is CSF continually being replaced?

Answer 57

yes

Question 58

what is the condition when there is a blockage in the ventricles and CSF can't circulate properly?

Answer 58

hydrocephalus

Question 59

what ventricle is most commonly blocked during hydrocephalus ?

Answer 59

cerebral aquaduct

Question 60

what are some causes of hydrocephalus ?

Answer 60

genetic prenatal viral infection intraventricular haemorrhage spina bifida cystica

Question 61

what cells are present as a single layer around the neural tube which go on to form neurons and glial cells?

Answer 61

neuroepithelial cells

Question 62

what four cells are produced from neuroepithelium in the CNS?

Answer 62

neuron astrocyte oligodendrocytes ependymal cell

Question 63

which cell in the CNS is not produced by neuroepithelium ?

Answer 63

microglia | - which comes from mesenchymal cells

Question 64

what are the two types of astrocytes ?

Answer 64

protoplasmic | fibrous

Question 65

what is the function of astrocytes ?

Answer 65

maintains BBB and supports neurons

Question 66

which cells form the PNS?

Answer 66

neural crest cells

Question 67

state some structures the neural crest cells form?

Answer 67

dorsal root ganglia sympathetic ganglia parasympathetic ganglia

Question 68

at which month is the spinal cord the same length as the vertebrae?

Answer 68

3 months

Question 69

at birth what spinal vertebrae does the spinal cord finish at?

Answer 69

L3

Question 70

as an adult what spinal vertebrae does the spinal cord finish at?

Answer 70

L1

Question 71

what are the hills and depressions in the cerebrum called?

Answer 71

``` hills = gyrus depressions = sulci ```

Question 72

what are the hills and depressions in the cerebellum called?

Answer 72

``` hills = folia depressions = sulci ```

Question 73

what is the advantage of having sulci and gyri in the cerebrum?

Answer 73

increases surface area and hence more cells and information can be fitted in the small area of the brain

Question 74

what is the very rare disorder when sulci and grey don't form on the brain?

Answer 74

lissencephaly

Question 75

what causes lissencephaly?

Answer 75

when there is defective neuronal migration

Question 76

what is polymicrogyria ?

Answer 76

when there are many small gyri

Question 77

what does polymicrogyria result in?

Answer 77

connection defects which results in neurological problems such as retardation, seizures and motor deficits

Question 78

what condition is caused by the zika virus ?

Answer 78

microcephaly

Question 79

what is the condition called when there is defected connection between the two hemispheres of the cerebrum ?

Answer 79

aegenesis corpus callosum

Question 80

what is the condition when there are CSF filled cysts in the cerebrum ?

Answer 80

porencephaly

Question 81

what condition results in large clefts or slits in the cerebrum ?

Answer 81

schizencephaly

Question 82

what condition results in the spinal cord being divided into two?

Answer 82

diastematomyelia

Question 83

what is a common cause of intellectual impairment in children?

Answer 83

maternal alcohol abuse

Question 84

why is the CNS vulnerable to defects form alcohol?

Answer 84

the CNS develops early in the 3rd week, therefore some women may not even realise they are pregnant so may continue drinking which could cause CNS defects

Question 85

what is the incidence of foetal alcohol syndrome per 1000?

Answer 85

1:1000

Question 86

what is the incidence of spina bifida per 1000?

Answer 86

1:1000

Question 87

as well as alcohol state some causes of intellectual impairment in children?

Answer 87

``` genetic (downs) radiation infection birth trauma postnatal insults (meningitis) ```