Development of Nervous system Flashcards

1
Q

Central nervous system

A

formed in week 3 as neural plate

neural plate -> neural tube -> brain and spinal cord

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2
Q

Peripheral nervous system

A

derived from:

  1. Neural crest cells: peripheral ganglia, Schwann cells, afferent nerve fibers
  2. Neural tube: preganglionic autonomic fibers, fibers innervating skeletal muscle
  3. Mesoderm: dura mater, CT around peripheral nerve fibers
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3
Q

Development of neural tube

A

week 3-4

  1. Neural plate: thickening of neural ectoderm
  2. Neural groove: formed by neural plate folding
  3. Neural fold: fuse in midline, neural crest differentation
  4. Neural tube: neural folds fuse + separate from surface ectoderm
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4
Q

Neural tube

A
  • cranial part: brain
  • caudal part: spinal cord
  • cavity: central canal of spinal cord + ventricles
  • anterior neuropore: lamina terminalis
  • posterior neuropore
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5
Q

Neural crest

A

gives rise to:

  • pseudounipolar ganglion cells (spinal, cranial nerve ggl)
  • Schwann cells
  • Multipolar ganglion cells (autonomic)
  • Leptomeninges
  • Chromaffin cells of suprarenal medulla
  • Pigment cells
  • Odontoblasts
  • Skeletal + connective components of pharyngeal arches
  • Aorticopulmonary septum of heart
  • Parafollicular cells
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6
Q

Placodes

A

thickenings of cephalic surface ectoderm

  1. Lens placode: lens, induced by optic vesicle
  2. Nasal placode: olfactory nerve, induce formation of olfactory bulb
  3. Otic placode: organ of Corti, spiral ggl, cristae amullares, maculae utriculi and sacculi, vestibular ggl, vestibulocochlear nerve
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7
Q

Stages of neural tube development: primary brain vesicles

A

week 4

  • proencephalon:otic vesicles, telencephalon+diencephalon
  • mesencephalon
  • rhombencephalon: metencephalon + myelencephalon
  • cephalic flexure
  • cervical flexure
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8
Q

Stages of neural tube development: secondary brain vesicles

A

week 6

  1. Telencephalon: cerebral hemispheres, olfactory bulb
  2. Diencephalon
  3. Mesencephalon: cerebral aqueduct
  4. Metencephalon: rhomboic lips -> cerebellum, pons
  5. Myelencephalon: medulla
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9
Q

Cells of neural tube wall

A

neuroepithelial cells that gives rise to:

  1. Neuroblasts: neurons in CNS
  2. Glioblasts:
    - macroglia: astrocytes, radial glial cells, oligodendroglia
    - ependymal cells: ependymocytes, tanycytes, choroid plexus cells
  3. Microglia
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10
Q

Layers of early neural tube wall

A
  1. Spinal cord:
    - ventricular zone(neurepith. layer): ependymal cells lining central canal, neurons and glial cells of spinal cord
    - intermediate zone(mantle layer): grey matter of spinal cord, alar and basal plates
    - marginal zone: white matter of spinal cord
  2. Brain
    - ventricular zone: ependymal cells lining ventricles, neurons and glial cells of brain
    - intermediate zone: cerebral cortex, basal ganglia
    - marginal zone: molecular layer of cortex
    - cortex: grey matter of cerebral hemispheres
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11
Q

Alar plate

A

dorsolateral thickening of intermediate zone of neural tube
gives rise to: sensory neuroblasts of dorsal horn
receives axons -> dorsal roots from dorsal root ganglion
becomes dorsal horn of spinal cord

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12
Q

Basal plate

A

ventrolateral thickening of intermediate zone of neural tube
gives rise to: motor neuroblasts of ventral and lateral horns
axons exit from spinal cord and form ventral roots
becomes ventral horn of spinal cord

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13
Q

Sulcus limitans

A

longitudinal groove in lateral wall of neural tube
appears week 4
separates alar ad basal plates
disappears in adult but remains in rhomboid fossa

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14
Q

Position changes of the spinal cord

A

week 8 spinal cord length = vertebral canal
at birth conus medullaris to L3, in adult L1-L2
disparate growth results in caudal equina + filum terminale

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15
Q

Development of Myelencephalon: Alar plates

A

Sensory neuroblasts give rise to:

  • dorsal column nuclei
  • inf. olivary nuclei
  • solitary nucleus
  • spinal trigeminal nucleus
  • cochlear and vestibular nuclei
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16
Q

Development of Myelencephalon: Basal plates

A

Motor neuroblasts give rise to:

  • hypoglossal nucleus
  • nucleus ambiguus
  • dorsal nucleus of vagal nerve
  • inf. salivatory nucleus
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17
Q

Development of Myelencephalon: Roof plate

A
  • forms roof of 4th ventricle
  • is the tela choroidea
  • invaginated by pal vessels -> choroid plexus
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18
Q

Development of Methencephalon: Pons

A
  1. Alar plate sensory neuroblasts:
    - solitary nucleus
    - vestibular and cochlear nuclei
    - spinal and principal trigeminal nuclei
    - pontine nuclei
  2. Basal plate motor neuroblasts:
    - abducent nucleus
    - facial nucleus
    - motor trigeminal nucleus
    - sup. salivatory nuclei
  3. Base of pons
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19
Q

Development of Methencephalon: Cerebellum

A
formed by rhombic lips - thickened alar plates
cerebellar plates gives rise to:
- vermis
- cerebellar hemispheres
- 3 layer cortex
- external granular layer
- folia and fissures
20
Q

Development of Mesencephalon

A
  1. Alar plate neuroblasts
    - superior and inferior colliculi
  2. Basal plate neuroblasts
    - trochlear nuclei
    - oculomotor nuclei
    - substansia nigra
    - red nucleus
21
Q

Epithalamus

A

Diencephalon

  • from embryonic roof plate and dorsal parts of alar plates
  • gives rise to: pineal body, tela choroidea, choroid plexus of 3rd ventricle
22
Q

Thalamus

A

Diencephalon

  • from alar plates
  • gives rise to: thalamic nuclei
23
Q

Hypothalamus

A

Diencephalon

  • from alar plate and floor plate
  • gives rise to: hypothalamic nuclei, mammillary bodies, neurohypophysis
24
Q

Subthalamus

A

Diencephalon

  • from alar plates
  • gives rise to: neuroblasts -> globes pallidus
25
Q

Hypophysis

A
  1. Anterior lobe:
    - from Rathke’s pouch
  2. Posterior lobe:
    - from ventral evagination of hypothalamus
26
Q

Development of Autonomic Nervous system

A
  1. Sympathetic neurvous system:
    - from basal plate of neural tube and neural crest cells
  2. Parasympathetic nervous system:
    - from basal plate of neural tube and neural crest cells
27
Q

Olfactory nerve

A
  • from nasal placode
  • mediates smell
  • capable of regeneration
28
Q

Optic nerve

A
  • from ganglion cells of retina
  • mediates vision
  • does not regenerate after transection
29
Q

Oculomotor nerve

A
  • from basal plate of rostral midbrain

- ocular motility, pupillary constriction, accommodation

30
Q

Trochlear nerve

A
  • from basal plate of caudal midbrain

- superior oblique m.

31
Q

Trigeminal nerve

A
  • motor division from basal plate of rostral pons
  • sensory divison from cranial neural crest
  • sensory + motor innervation of 1st pharyngeal arch
32
Q

Abducent nerve

A
  • from basal plate of caudal pons

- abduction of globe

33
Q

Facial nerve

A
  • motor division from basal plate of pons
  • sensory division from cranial neural crest
  • sensory + motor innervation of 2nd pharyngeal arch
34
Q

Vestibulocochlear nerve

A
  • from otic placode
  • vestibular - balance and equilibrium
  • cochlear - hearing
35
Q

Glossopharyngeal nerve

A
  • motor division from basal plate of medulla
  • sensory division from cranial neural crest
  • sensory + motor innervation of 3rd pharyngeal arch
36
Q

Vagal nerve

A
  • motor division from basal plate of medulla
  • sensory division from cranial neural crest
  • sensory + motor innervation of 4th and 6th pharyngeal arch
37
Q

Accessory nerve

A
  • from basal plate of spinal segments C1-6

- sternocleidomastoid m. and trapezius m.

38
Q

Hypoglossal nerve

A
  • from basal plate of medulla

- intrinsic and extrinsic muscles of tongue

39
Q

Development of Choroid plexus

A
  • from roof plates of rhombencephalon and diencephalon
40
Q

Ventral nerve roots

A

week 4
nerve cells in basal plates of spinal cord
gets collected into bundles

41
Q

Dorsal nerve roots

A

originates from dorsal root ganglia
central processes grow into the spinal cord
distal processes join the ventral nerve roots to form spinal nerve

42
Q

Myelination of nerves

A

4th month
Schwann cells (from neural crest) myelinated peripheral nerves -> neurilemma sheath
Oligodendroglial cells myelinate nerve fibers in spinal cord

43
Q

Development of Telencephalon: Cerebral hemispheres

A

5th week
Bilateral evagination of lateral wall of prosencephalon
Corpus striatum: basal part of hemispheres grow + bulges into lateral ventricle
Choroid plexus: hemisphere wall with single layer of ependymal cells + vascular mesenchyme
Hippocampus: thickening of wall of hemisphere

44
Q

Development of Telencephalon: Cortex development

A

from pallidum- paleopallidum + neopallidum

Neopallidum: neuroblasts migrate to subpial position -> mature neurons

45
Q

Development of Telencephalon: Olfactory bulbs

A

Olfactory placodes from neural crest cells + ectoderm of frontonasal prominence
Olfactory bulb from neural crest cells + floor of telencephalon
Sensory neurons of nasal epithelium from cells in nasal placodes

46
Q

Development of Telencephalon: Commissures

A

Anterior commissure:lamina terminalis
Hippocampal commissure: fibers from hippocampus -> converge on lamina terminalis
Corpus callosum: week 10. Small bundle in lamina terminalis -> expands due to neopallidum
Posterior + habenular
Optic chiasma