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Neuro Endocrine 2 > development of the brain > Flashcards

development of the brain Flashcards

1
Q

when and where does the neural plate and neural groove form?

what is it induced by?

A

develop on the posterior aspect of the trilaminar embryo (3 weeks)

Induced by the notochord

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2
Q

When does Neurulation begin and what components develop into what?

A

Neurulation begins 4th week
-Cranial 2/3 = 4th pair of somites and becomes future brain

-Caudal 1/3 = Future spinal cord

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3
Q

Where does the neural tube form?

When does the neurotubes close

A

Neural tube first forms at the 5th somite

Cranial neurotube closes at 25 days

Caudal neurotube closes at 27 days

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4
Q

what are the three primary brain vesicles

A

Forebrain: Prosencephalon

Midbrain: Mesencephalon

Hindbrain: rhombencephalon

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5
Q

What are the 5 secondary brain vesicles and when do they develop?

A

5th week

Telencephalon and Diencephalon (via the forebrain division)

Mesencephalon (midbrain does not divide)

Metencephalon, and Myleencephalon (via division of the hindbrain)

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6
Q

What are the walls and cavities derived from the secondary vesicles: Telencephalon

A

Cerebral hemispheres

Lateral ventricles

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7
Q

What are the walls and cavities derived from the secondary vesicles: Diencephalon

A

Thalamus, etc

Third ventricle

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8
Q

What are the walls and cavities derived from the secondary vesicles: Mesencephalon

A

Midbrain

Cerebral Aqueduct

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9
Q

What are the walls and cavities derived from the secondary vesicles: Metencephalon

A

Pons, Cerebellum

Upper part of fourth ventricle

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10
Q

What are the walls and cavities derived from the secondary vesicles: Myelencephalon

A

Medulla

Lower part of fourth ventricle

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11
Q

What are the three flextures of the brain and when do they occur and what direction

A

Midbrain or mesencephalic flexure (towards trunk bend)

Cervical flexure (hindbrain/SC junction and flexes toward the trunk)

Unequal growth produces the pontine flexure (extension away from trunk) occurs at the Meten-myelencephalon junction

These occur at week 5 and lead to producing considerable variation position of the gray and white matter

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12
Q

what makes up the hindbrain

A

Cervical flexure to Pontine flexure

Myelencephalon - Medulla oblongta

Metencephalon - Pons and Cerebellum

Cavity: Fourth ventricle and central canal in the medulla

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13
Q

What makes up the caudal mylencephalon

A

Alar plates migrate into the marginal zone give rise to
nucleus gracilus, nucleus cuneatus

Pyramids consisting of corticalspinal tracts

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14
Q

What makes up the rostral myelencephalon

A

is wide and flat

Pontine Flexure: causes the walls of medulla to move laterally

Roof plate: greatly thinned
cavity becomes part of future 4th ventricle

Alar plates become lateral to the basal plates
motor nuclei develop medial to sensory nuclei

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15
Q

What do neuroblasts in the basal plate of the medulla develop to

A

columns motor neurons. efferent

General somatic efferent
special viscereal efferent
general visceral efferent

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16
Q

What do neuroblasts in the alar plate of the medulla develop to

A

columns of Afferent neurons

general visceral afferent
special visceral afferent
general somatic afferent
special somatic afferent

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17
Q

What develops out of the metencephalon

A

forms the pons and the cerebellum

superior part of the 4th ventricle

Cerebellum develops from dorsal parts of alar plates

  • cerebellar swellings project into 4th ventricle
  • fuse in median plane
  • overgrows rostral 4th ventricle and overlap the medulla and pons
18
Q

How is the choroid plexus formed

A

Ependymal roof of 4th ventricle is covered externally by pia mater
-these two together make up the tela choroidea

the tela choroidea will invaginate the 4th ventricle to form the choroid plexus

19
Q

what is the epithelial lining of the choroid plexus derived from? the stroma?

A

neuroepithelium

stroma is the mesenchymal cells

20
Q

how are the median and lateral aperatures formed

A

the roof of the 4th ventricle evaginates in three locations which will rupture making the apertures
-this allows for the CSF to enter the subarachnoidspace

21
Q

What do the neuroblasts of the alar plate in the midbrain give rise to

A

Tectum which will form the superior and inferior colliculi

22
Q

What do neuroblasts of basal plates of the midbrain give rise to

A

tegmental nuclei (red nuclei, reticular nuclei, CN III, and IV nuclei

23
Q

What does the substantia nigra derive from

A

is still arguable could be basal plate or alar plate cells that migrate ventrally

24
Q

how is the cerebral aqueduct formed

A

formed in the midbrain due to neural canal narrowing

25
Q

What develops in the Diencephalaon

A

swellings of the lateral walls of the third ventricle will form the thalamus, hypothalamus and the epithalamus

Epithalamic sulcus seperates the thalamus and epithalamus

Hypothalamic sulcus seperates the thalamus and the hypothalamus

26
Q

what does the the hypothalamus arise from?

A

neuroblasts in intermediate zone

  • Endocrine and homeostatic nuclei develop
  • Mamillary bodies form on ventral surface of the hypothalamus
27
Q

How does the epithalamus develop?

A

develops from the roof and dorsal portion of the lateral wall

forms the epithalamic swellings which are large but then will become relatively small

28
Q

How does the Pineal gland form

A

Develops as a median diverticulum of the caudal part of the roof of the diencephalon
-proliferation of cells in its walls converts it into the solid cone shaped gland

29
Q

How does the Anterior lobe of the Pituitary gland develop

A

Oral ectoderm

Hypophyseal diverticulum (rathkes pouch) from the roof of the stomodeum migrates up gives rise to:
Pars anterior
pars tuberalis
pars intermedia

the tissue type: adenohypophysis

connection to the oral cavity degrades week 6

30
Q

How does the Posterior lobe of the Pituitary gland develop

A

Neuroectoderm

Neurohypophyseal diverticulum from the floor of the diencephalon migrate down (connected to brain via the infundibulum (passes between developing bones of the cranium))

  • Pars nervosa
  • Infundibular stem
  • Median eminence
31
Q

What consists in the telencephalon and how does it form the cerebral hemispheres

A

median part and two telencephalic/cerebral vesicles, primordia of the cerebral hemispheres

the median cavity will form the anterior 3rd ventricle

communication of cerebral hemispheres with 3rd ventricle is done via the interventricular foramina

The hemispheres become C-shaped
-due to cortex rapidly proliferating but deeper nuclei do not

32
Q

When do the optic vesicles appear on the telencephalon

A

as closure of the rostral neuropore occurs the optic vesicle will appear

33
Q

Where does the choroid plexus form in the 3rd ventricle

A

the medial wall of the cerebral hemisphere which is continuous with the roof of the 3rd ventricle will develop the choroid plexus

34
Q

How does the falx cerebri form

A

from mesenchyme trapped in the longitudinal fissure which occurs via the cerebral hemispheres expanding to meet each other in the midline causing the medial surfaces to flatten

35
Q

Cavities of what secondary brain vesicles make up the 3rd ventricle

A

Telencephalon (anterior part)

Diaencephalon (the rest)

36
Q

Holoprosencephaly

A

Incomplete separation of the cerebral hemispheres

Defectss in forebrain development often cause facial anomalies resulting from a reduction of FNP

Cyclopia, premaxillary agenesis, proboscis, single-nostril, hypotelorism, facial clefts

genetic that causes an inhibition of cholesterol syntesis

37
Q

What are the Cerebral commissures and what are they connecting

A

groups of nerve fibers interconnecting the cerebral hemispheres
-lamina terminalis: rostral end of the forebrain

Anterior commisure and hippocampal commissure form first

  • anterior interconnects the olfactory bulb with the hemispheres and temporal lobes
  • Hippocampal connects the hippocampal formations

Posterior commisure: posterior to upper portion of the cerebral aqueduct and is important in the bilateral pupillary light reflex

Corpus callosum forms the hemispheres
-anterior portion forms first then the posterior portion in fetal life

Lamina terminalis forms the septum pellucidum which is a thin plate of brain tissue containing nerve cells and fibers

38
Q

Agenesis of corpus callosum

A

complete or partial absence of the corpus callosum

the condition may be asymptomatic but seizure and mental deficiency are common

39
Q

How does growth of the cerebral hemispheres occur

A

Cortex is initially ssmooth but growth gives the development of gyrus and sulci

has zones: ventricular, intermediate and marginal and subventricular

cortical layers are layed down deep to superficial

  • neurons migrate through the deeper layer to establish superficial layers
  • inside out development
40
Q

Lissencephaly

A

incomplete neuronal migration to cerebral cortex during 3-4 months of gestation

smooth cerebral surface

  • Pachygyria: broad thich gyri
  • Agyria: lack of gyri
  • Neuronal heterotopia: cells in aberrant positions compared to a normal brain
  • enlarged ventricles and malformed corpus callosum

initially appear normal and then develop seizures, profound mental deficiencies, spastic guadriplegia

41
Q

Microcephaly

A

calvaria and brain are small but face is normal sized

significant mental deficiencies due to brain underdevelopment

reduction in brain growth

Causes:

  • Autosomal recessive primary microcephaly
  • ionizing radiation
  • infectious agents (cytomegalovirys, rubella virus, toxoplasma gondii)
  • Maternal alcohol abuse

Neuro Endocrine 2 (24 decks)

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