SM02 Mini3 Flashcards

1
Q

explain the process of primary neurulation

A
  • notocord (derived from epiblast cells) stimulates process
  • neural plate formation on the ectoderm above the notochord
  • neural groove/crest formation D20/21
  • neural tube folding & closure starts in middle
  • closing progesses caudally & cranially
    • cranial closes first
    • all closed by end of 4th week
  • sonic hedgehog (SHH) differentiates ventral/motor neurons
  • bone morphogenetic proteins (BMPs) differentiate dorsal/somatosensory neurons
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2
Q

derivatives of neuroectoderm

A
  • ependymal cells: glial cells that line ventricles
  • bipolar neuroblast→ multipolar neuroblast
  • glioblasts→
    • astrocytes→ fibrillar & protoplasmic
    • oligodendrocytes
  • NOT ​microglia
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3
Q

microglia are derived from

A

mesenchyme

b/c they are the macrophages of the brain

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4
Q

when does myelination occur?

A

mostly after birth

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5
Q

what are the primary brain vesicles?

A

prosencephalon

mesencephalon

rhombencephalon

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6
Q

prosencephalon develops into…

A

telencephalon & diencephalon

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7
Q

mesencephalon develops into…

A

the midbrain

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8
Q

rhombencephalon develops into…

A

metencephalon & myelencephalon

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9
Q

structures of the telencephalon

A

cerebral hemispheres

olfactory tract/bulb

basal nuclei

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10
Q

structures of the diencephalon

A

thalamus

hypothalamus

epithalamus

pituitary gland

pineal gland

optic vesicle/cups

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11
Q

structures of the metencephalon

A

pons & cerebellum

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12
Q

structures of the myelencephalon

A

medulla

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13
Q

spaces of the telencephalon

A

lateral ventricle x2

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14
Q

space of the diencephalon

A

thrid ventricle

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15
Q

space of mesencephalon

A

cerebral aquedcut

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16
Q

space of metencephalon

A

upper half of fourth ventricle

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17
Q

space of myelencephalon

A

lower half of fourth ventricle

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18
Q

thalamus is derived from

A

diencephalon

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19
Q

medulla is derived from

A

myelencephalon

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20
Q

pons is derived from

A

metencephalon

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21
Q

cerebellum is derived from

A

metencephalon

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22
Q

cerebrum is derived from

A

telencephalon

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23
Q

pituitary is derived from

A

diencephalon

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24
Q

cervical flexure

A

bend of primary brain vesicles between rhombencephalon & spinal cord

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25
Q

cephalic flexure

A

bend in the primary brain vesicles between the mesencephalon & rhombencephalon

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26
Q

pontine flexure

A

bend in secondary brain vesicles between metencephalon & myelencephalon

generates fourth ventricle

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27
Q

isthmus rhombencephalon

A

narrow portion of embryonic neural tube connecting rhombencephalon to mesencephalon

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28
Q

hemispheric sulcus

A

groove separating diencephalon from telencephalon

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29
Q

parts of the midbrain

A

dorsal to ventral

  • tectum: composed of superior & inferior caliculus
    • superior→visual
    • inferior→ auditory
  • tegmentum
    • w/cerebral aqueduct in the middle
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30
Q

how are the derivatives of the metencephalon related?

A

pons is found ventrally

cerebellum is dorsal

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31
Q

sulcus limitans

A

groove that demarcates the border between sensory & motor neurons throughout the CNS

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32
Q

secondary neurulation

A

folding of the primary & secondary brain vesicles

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33
Q

what causes neural tube defects?

A

failure of the neural tube to close

OR

failure of cerebral hemisphere separation

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34
Q

techniques for prenatal neural tube defects

A

amniocentesis or ultrasound

35
Q

week 3 major developments

A

neural groove & folds

3 primary vesicles

cervical & cephalic flexures

appearance of motor neurons

36
Q

week 4 major developments

A
  • neural tube closure
    • begins D21/22
    • rostal D24/25
    • caudal D26/27
  • neural crest cells begin migration
37
Q

week 5 major developments

A
  • optic vesicle formation
  • pontine flexure
  • 5 secondary vesicles visible
  • sensory nerves grow into CNS
  • formation of other minor structures
38
Q

major developments of W6-7

A

telencephalon enlargement around diencephalon

basal ganglion prominent

secondary neurulation complete

cerebellum & optic nerve begin

insula formation

39
Q

major developments of W8-12

A

neural proliferation & migration

cerebral & cerebellar cortex begin

anterior commissure & optic chiasm formation

internal capsule

reflexes appear

40
Q

major developments of W12-16

A

neuronal proliferation & migration

glial differentiation

corpus callosum formation

41
Q

major developments of W16-40

A

neuronal migration

cortical sulci formation

synpase formation

glial proliferation & start of myelination

42
Q

spina bifida occulta

A

incomplete vertebra formation

usually benign

covered with a tuft of hair

43
Q

spina bifida

A

neural tube fails to close caudally

associated w/folic acid deficiency of mother during pregnancy

44
Q

meningocele

A

protrusion of the meninges

fluid filled sac

sub arachnoid space

can be seen caudally in spina bifida or proximally in encephalocele

45
Q

spina bifida meningomyelocele

A

protrusion of meninges & axons (usually filum terminale)

may pull hind brain into foramen magnum causing hydrocele

46
Q

encephalocele

A

herniation of the meninges and sometimes brain from openings in skull

  • meningocele: just meninges (dura & arachnoid)
  • meningoencephalocele: meninges & brain tissue
  • meningohydroencephalocele: meninges, brain tissue, & ventricular lumen
47
Q

anencephaly

A

neural tube fails to close rostrally

associated w/maternal type I diabetes

vault of skull fails to form

exposed brain tissue degenerates

48
Q

holoprosencephaly

A

failure of L & R hemispheres to separate

  • lobar: one central incisor
  • semilobar: cleft palate
  • alobar: cyclopia

usually fatal

related to SSH mutations, fetal alcohol syndrome

49
Q

which neuroembryologic signaling protein is found dorsally? ventrally?

A

BMPs dorsally

SHH ventrally

50
Q

neuroepithelium

A

thick pseudostratified epithelium

found as wall of neural groove& extends over entire thickness of wall

give rise to neuroblasts & gliablasts

51
Q

what happens to neural ectoderm that is pinched off when the neural tube rolls up?

A

neural crest cells

develop into PNS

52
Q

spina bifida w/rachischisis

A

neural tissue is exposed

often become necrotic

most severe type of spina bifida

53
Q

what structures are important for air conduction in the auditory system?

A

the external ear: pinna & external auditory meatus

54
Q

what structures are responsible for neural conduction of sound?

A

inner ear: vestibule & cochlea

and CN VIII vestibulocochlear nerve

and ascending: cochlear nucleus

55
Q

otalgia

A

ear pain

56
Q

medical term for external ear infection?

A

acute ototis externa

57
Q

what are the coiled tubular glands found in the external auditory meatus?

A

cerminous glands

58
Q

how is the outer ear formed?

A

from the auricular hillock

1st & 2nd pharyngeal arches

six bumps (3 from each arch) rotate counter clockwise to form pinna

59
Q

how does the tympanic membrane form?

A

fusion of the ectoderm of the 1st pharyngeal groove and the endoderm of the 1st pharyngeal pouch

60
Q

what is the pinna made of?

A

plate of elastic cartilage covered by thin skin

61
Q

what is the embryologic origin of the auditory ossicles?

A

accumulation of ectoderm from the 1st & 2nd pharyngeal arches

forms cartilage

and later bone

62
Q

how are the vestibule and cochlea formed?

A

otic vesicle of ectoderm pinches off and migrates inward

develops into otocyst

forms vestibule & cochlea

bone labyrinth forms from surrounding mesenchyme

63
Q

where is perilymph found?

A

scala vestibuli & scala tympani of the cochlea

64
Q

where is Reissner’s membrane?

A

between the scala vestibuli and the scala media

65
Q

where is endolymph found?

A

scala media

66
Q

what type of cells form Reissner’s membrane?

A

2 layers of simple squamous cells

67
Q

what forms the spiral ligament?

A

thickened periosteal lining of bony labyrinth

connects to bailar membrane of scala media

68
Q

where is the basilar membrane?

A

between the scala media and scala tympani

69
Q

what is the tectorial membrane?

A

gelatinous membrane that extends over hair cell in the organi of Corti

70
Q

where are Deiters’ cells found?

A

aka outer phalangeal cells

supporting cells of the outer hair cells in the organ of Corti

71
Q

what cells are supported by the inner phalangeal cells?

A

inner hair cells

72
Q

what is the main structural differences between the inner & outer hair cells?

A
  • inner hair cells
    • rounded
    • found in the single row along the inner pillar cells
    • row forms U shape
  • outer hair cells
    • more columnar in shape
    • form three rows outward from the outer pillar cells
    • rows are in V or W shape
73
Q

whic type of cochlear hair cell has a larger efferent than afferent neuronal connection?

A

outer hair cells

74
Q

where are the ampullae found?

A

one on each vestibular canal

75
Q

where are the maculae found?

A

one on the utricle and another on the saccule

76
Q

function of the macula

A

detect linear movement of the head & gravity

77
Q

function of the ampulla

A

detection of angular momentum of the head

78
Q

where is the cupula found?

A

in the ampulla

79
Q

what are the main difference between the hair cell types found in the vestibule?

A
  • type I
    • round, bulbous cell body
    • afferent axon surrounds cell body
    • myelinated afferent axon
  • type II
    • columnar shape
    • unmyelinated afferent axon
80
Q

cerumen is a mixture of secretions from which glands?

A

ceruminous & sebaceous

81
Q

umbo

A

pit of the concave tympanic membrane

caused by connection to malleus

82
Q

how do the scala vestibuli and scale tympani communicate?

A

via the helicotrema

83
Q

stria vascularis

A

richly vascularized pseudostratified epithelium

secretes endolymph

lateral border of cochlear duct

84
Q
A