embryology and congenital malformations

Question 1

what does the nervous system develop from?

Answer 1

embryonic ectoderm

Question 2

when does the CNS appear?

Answer 2

beginning of the 3rd week of pregnancy

Question 3

what is the neural plate?

Answer 3

thickening of the ectoderm anterior to the primitive node

Question 4

how are the neural folds formed?

Answer 4

the edges of the neural plate thicken and move upwards

Question 5

how is the neural tube formed?

Answer 5

neural folds migrate towards each other and fuse at the midline

Question 6

when does the anterior (cranial/rostral neuropore) part of the neural tube close?

Answer 6

around 25 days

Question 7

when does the posterior (caudal neuropore) close?`

Answer 7

day 27

Question 8

what defects can present as a result of the neural tube failing to close properly?

Answer 8

anencephaly
encephalocoele
spina bifida

Question 9

what is anencephaly?

Answer 9

failure of the anterior neuropore to close

Question 10

what is the result of the anterior neuropore failing to close?

Answer 10

skull fails to form

brain tissue degenerates

Question 11

what is craniorachischisis?

Answer 11

failure of anterior neuropore and rostral neural tube to close

Question 12

what is encephalocoele?

Answer 12

herniation of cerebral tissue through a defect in the skull

Question 13

what causes encephalocoele?

Answer 13

failure in closure of the rostral neural tube

Question 14

what causes spina bifida?

Answer 14

defective closure of the caudal neural tube

Question 15

what is spina bifida?

Answer 15

non fusion of the vertebral arches

Question 16

what is spina bifida occulta?

Answer 16

failure of the embryonic halves of the vertebral arch to grow normally and fuse

Question 17

what is spina bifida cystica?

Answer 17

embryonic halves of the vertebral arch fail to grow normally and fuse AND the spinal cord and/or meninges can protrude through the defect

Question 18

what are the 3 types of spina bifida cystica?

Answer 18

with meningocele
with meningomyelocle
with myeloschisis

Question 19

what is spina bifida with meningocele?

Answer 19

protrusion of the meninges and CSF

Question 20

what is spina bifida with meningomyelocle?

Answer 20

when the nerve roots and/or spinal cord are included in the protruding sac

Question 21

what symptoms can present with SB with meningomyelocele?

Answer 21

neurological deficits - loss of sensation and muscle paralysis

Question 22

what is SB with meningomyelocele associated with often?

Answer 22

hydrocephalus

Question 23

what is myeloschisis?

Answer 23

when the spinal cord in the affected area is open due to the failure of the neural folds to fuse

Question 24

what measures are taken to try and prevent neural tube defects?

Answer 24

folic acid supplements

Question 25

how can neural tube defects be diagnosed prenatally?

Answer 25

maternal blood screening amniocentisis ultrasounf

Question 26

what are some risk factors for NTD?

Answer 26

genetic predisposition nutritional environmental

Question 27

when does development of the brain vesicles begin?

Answer 27

with closure of the anterior neuropore

Question 28

what is the prosencephalon (forebrain) composed of?

Answer 28

telencephalon | diencephalon

Question 29

what is the rhombencephalon (hindbrain) composed of?

Answer 29

metencephalon | myelencephalon

Question 30

when does the cephalic flexure appear?

Answer 30

end of the 3rd week

Question 31

where is the cephalic flexure located?

Answer 31

between the midbrain and the hindbrain

Question 32

when does the cervical flexure appear?

Answer 32

end of the 4th week

Question 33

where is the cervical flexure located?

Answer 33

between the hindbrain and the spinal cord

Question 34

when does the pontine flexure appear?

Answer 34

5th week

Question 35

where is the pontine flexure located?

Answer 35

in the hindbrain between the metencephalon and myelencephalon

Question 36

what develops from the telencephalon?

Answer 36

cerebral hemispheres hippocampus basal ganglia

Question 37

what develops from the diencephalon?

Answer 37

thalamus hypothalamus pituitary gland pineal gland

Question 38

what forms the ventricular system of the head?

Answer 38

lumen of the neural tube

Question 39

when does CSF begin to form?

Answer 39

5th week of pregnancy

Question 40

how does CSF drain into the subarachnoid space?

Answer 40

via openings in the roof of the 4th ventricle

Question 41

where is CSF absorbed?

Answer 41

into the venous system

Question 42

what is hydrocephalus?

Answer 42

accumulation of CSF

Question 43

what does hydrocephalus result in?

Answer 43

enlarged brain and craniam

Question 44

what is a common cause of hydrocephaly?

Answer 44

blocked cerebral aqueduct

Question 45

what can cause i blocked cerebral aqueduct?

Answer 45

genetic prenatal viral infection IV haemorrhage

Question 46

what kind of cells make up the neural tube

Answer 46

single layer of rapidly dividing neuroepithelial cells

Question 47

what kind of epithelium makes up the neural tube?

Answer 47

pseudostratified epithelium

Question 48

what cells of CNS are not produced by neuroepithelium?

Answer 48

microglia

Question 49

what nevous system are neural crest cells part of?

Answer 49

PNS

Question 50

what process of neural crest cells forms the body of the spinal cord?

Answer 50

peripheral process

Question 51

what process of neural crest cells forms the dorsal horn of the spinal cord?

Answer 51

central process

Question 52

how long is the spinal cord in the 3rd month of pregnancy?

Answer 52

entire length of vertebral column

Question 53

what forms sympathetic and parasympathetic ganglia?

Answer 53

neural crest cells

Question 54

how are sulci and gyri of the brain formed?

Answer 54

rapid growth of the cerebral hemispheres

Question 55

what causes lissencephaly?

Answer 55

defective neuronal migration

Question 56

what is lissencephaly?

Answer 56

failure of gyri and sulci to develop?

Question 57

what does lissencephaly cause?

Answer 57

severe mental impairment failure to thrive seizures abnormal muscle tone

Question 58

what is polymicroglia?

Answer 58

excessive number of small gyri

Question 59

what is porencephaly?

Answer 59

CSF filled cysts or cavities in the brain

Question 60

what is schizencephaly?

Answer 60

large clefts or slits in the brain

Question 61

what is diastematomyelia?

Answer 61

spinal cord split longitudinally into 2 parts

Question 62

what are some symptoms of diastematomyelia?

Answer 62

scoliosis weakness of lower extremities loss of sensation

Question 63

what is a common cause of newborn intellectual impairment?

Answer 63

maternal alcohol abuse