Embryology of the Nervous System Flashcards Preview

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Flashcards in Embryology of the Nervous System Deck (90):
1

notochord

iniates entire process of neurulation

signals formation of neural plate (thickened cells)
-dorsal surface of embryo

lateral edges start to fold

2

neural tube

formed from fusion of neural tube

3

cranial neuropore closure

day 25

4

caudal neuropore closure

day 27

5

neural tube

forms all of CNS
-brain and spinal cord

6

neural crest cells

form just above neural tube
-from neuroectoderm
-migrate into underlying mesoderm

become all of the PNS

7

fate of cranial neural crest

bones, cartilage, fascia, ligaments and tendons of face, neck

sensory ganglia and autonomic ganglia

8

fate of spinal neural crest

dorsal root ganglion
autonomic ganglion
heart - fibrous skeleton

9

shared fate of cranial and spinal neural crest

meninges
schwann cells
melanocytes

10

spinal cord formation

neural tube caudal to 4th pair of somites forms spinal cord

11

cells of neural tube

neuroectoderm
-migrate out away from lumen
-establish regions of spinal cord

12

zones of neuroectoderm migration

ventricular zone
mantle zone
marginal zone

13

ventricular zone

embryo - thick, pseudostratified epithelium called neuroepithelium

adult - simple layer of ependymal cells

14

derivatives of ventricular zone

give rise to all neurons and most glia of spinal cord

15

mantle zone

zone superficial to the neuroepithelium
composed of neuronal cell bodies
alar and basal plates

forms gray matter

16

sulcus limitans

separates basal and alar plates of mantle zone

17

basal plate

form motor, ventral horn

18

alar plate

form sensory, dorsal horn

19

marginal zone

outermost layer
composed of nerve processes (axons/dendrites)

form white matter

20

derivatives of neuroepithelium

neuroblasts
gliablasts

21

neuroblasts

form ventral horn motor neurons
and dorsal horn sensory neurons

22

gliablasts

form astrocytes and oligodendrocytes

23

spinal nerve

form from ventral root and dorsal root

24

dorsal root ganglion

derived from neural crest

25

microglial cells

derived from mesenchymal cells
migrate in later

26

cranial portion of neural tube

forms three vesicles

27

prosencephalon

forebrain

28

mesencephalon

midbrain

29

rhombencephalon

hindbrain

30

3 primary vesicles

prosencephalon
mesencephalon
rhombencephalon

31

secondary vesicles

telencephalon
diencephalon
mesencephalon
metencephalon
myelencephalon

32

derivatives of prosencephalon

telencephalon and diencephalon

33

derivatives of rhombencephalon

metencephalon and myelencephalon

34

lumen of telencephalon

lateral ventricles

35

lumen of mesencephalon

cerebral aqueduct

36

lumen of diencephalon

third ventricle

37

lumen of rhombencephalon

fourth ventricle

38

flexures in brain

result of differential growth

cervical - SC to myelencephalon
cephalic - rapid cerebrum growth
-takes place at midbrain
pontine -

39

derivatives of telencephalon

cerebral hemispheres

40

derivatives of diencephalon

thalamus, hypothalamus, pituitary, optic vesicles, pineal

41

derivatives of mesencephalon

midbrain

42

derivatives of metencephalon

pons
cerebellum

43

derivatives of myelencephalon

medulla

44

lumen of metencephalon and myelencephalon

fourth ventricle

45

tela choroidea

pia mater + ependymal layer of cells

proliferates and evaginates into ventricles

in roof of third and fourth ventricles
in medial walls of lateral ventricles

46

brainstem vs. spinal cord

similar development
-alar and basal plates
-alar, dorsal, sensory
-ventral, vasal, motor

however, gray matter is in distinct nuclei - not columns
-also, sensory nuclei displaced laterally

47

development of myelencephalon

forms medulla
get three layers, like in SC

48

pontine flexure

lateral flexures
pushes alar plates of myelencephalon laterally

49

order of nuclei in myelencephalon

lateral to medial

alar - somatic afferent > SVA > GVA
basal - GVE > SVE > somatic efferent

SA > SVA > GVA > GVE > SVE > SE

** motor - medial
**sensory - lateral

50

CNs of myelencephalon

CN VIII, IX, X, XII

8,9,10, 12

51

development of metencephalon

forms pons and cerebellum

52

pons development

portion of metencephalon
-three layers like in SC
-basal - motor
-alar - sensory

some alar plate cells migrate into white mater
-become nuclei

53

cranial nerves with pons

V, VI, VII, VIII
5,6,7,8

54

cerebellum development

portion of metencephalon
-formation of rhombic lip
-fuse over roof plate
-form cerebellar plate
-waves of neuroblasts migrate through marginal layer
-form outer cerebellar cortex
-gray matter - external
-white matter - internal

55

cerebellar plate

fusion of rhombic lips
-forms entire cerebellum

56

deep nuclei of cerebellum

derived from original marginal layer

57

mesencephalon development

forms midbrain
from 3 layers, like SC

basal - motor
alar - sensory

58

CNs of midbrain

mesencephalon

III, IV
3, 4

59

roof of diencephalon

forms epithalamus
-contains choroid plexus
-gives rise to pineal gland

60

alar plates of diencephalon

alar plate forms two swellings
superior and inferior

61

superior swelling of alar plate in diencephalon

forms thalamus
-bulges into third ventricle

70% of people have interthalamic adhesion form

62

inferior swelling of alar plate in diepcephalon

hypothalamus

63

neurohypophysis formation

downgrowth of diencephalon neuroectoderm
posterior pituitary

64

adenohypophysis formation

upgrowth of oral ectoderm
anterior pituitary

65

optic nerve formation

from diencephalon
-evagination of brain

also, most of retina

66

lamina terminalis

where the cranial neuropore closes
-in diencephalon

67

radial glial cell

act like ladders for neurons in the telencephalon development

to form outer gray cortex

68

new neurons in telencephalon

6 waves of cells migrate
-youngest cells most external

69

development of telencephalon

two lateral diverticula will form cerebral hemispheres
-neuroblasts migrate
-gray - superficial
-white - deep

also forms corpus striatum

70

neuroblast waves in telencephalon?

waves migrate through marginal zone
-along radial glial cells**

71

continued growth of cortex during final part of fetal life

gyri - outward convolutions
sulci - fissures

72

corpus striatum formation?

swelling within floor of cerebral hemispheres

73

CN of telencephalon

olfactor
CN I

74

CN of diencephalon

CN II

75

CN of mesenephalon

CN III, IV

76

spinal accessory nerve formation

from cervical spinal cord

77

spina bifida occulta

more common
no neural involvement

only defect in vertebral arch

78

spina bifida cystic

more severe
do have neural involvement

meningocele - only meninge
meningomyelocele - meninge and spinal nerve/spinal cord involvement

79

spina bifida

neural tube does not fuse posteriorly
-also, vertebral arch does not fuse

80

anencephaly

aka meroencephaly
caused by cranial neuropore not closing
-forebrain - does not form
-no di or telencephalon formation

81

craniorachischisis

closure defect extends in spinal cord

82

microcephaly

small cranium
formed from brain underdevelopment

83

encephalocele

failed neural tube fusion and defect in skull
-foramen magnum or lamdoid suture

-allows portion of CNS to protrude
-results in cyst-like structure at base of skull

84

meningocephalocele

meninges and part of brain bulge through defect

85

meningohydroenephalocele

meninges, brain, and part of ventricular system bulge through defect

86

congenital hydrocephalus

increased CSF within ventricles
-imbalance in production and absorption
-most often obstruction cause

dilation of ventricles proximal to obstruction

skulls expand (sutures not fused)

thin calvaria bone is result

87

Tx for congenital hydrocephalus

shunt procedure
cannula into ventricle system

88

common obstuction site for hydrocephalus

IV foramina of monro**
cerebral aqueduct of silvius**
lateral apertures of luschka
median aperture of magendie

89

arnold chiari syndrome

herniation of cerebellar hemispheres through foramen magnum

-underdevelopment of posterior cranial fossa
-skull defect

often associated with spina bifida cystica

type I - congenital

presentation - fingerline projection of cerebellum through the foramen magnum

90

holoprosencephaly

rare
failure of forebrain neural tube to form cerebral hemispheres

lateral ventricles fuse