Development of the Brain Flashcards

1
Q

explain the development to the brain

A
  • The cranial part of the neural tube becomes the brain
  • The neural tube dilates in the 4th week which produces the:
  • forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon)
  • during the 5th week of development, 5 secondary brain vesicles were developed when the fore and hindbrain divide
  • head folding causes the development of the midbrain (cranial) and cervical flexure (caudal)
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2
Q

What brain vesicles are formed from the forebrain

A
  • telencephalon (cranial)
  • diencephalon (caudal)
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3
Q

What brain vesicles are formed from the hindbrain

A
  • metencephalon
  • myelencephalon
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4
Q

What are the adult derivatives of the secondary brain vesicles

A
  • cerebrum
  • thalami
  • midbrain
  • pons and cerebellum
  • medulla
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5
Q

What do the 5 vesicles of the brain differentiate to

A
  • Telencephalon: cerebral hemispheres, lateral ventricles
  • Diencephalon: Thalamus, hypothalamus, epithalamus, third ventricle
  • Mesencephalon: anterior & posterior colliculi, cerebral aqueduct of Sylvius
  • Metencephalon: cerebellum, pons, upper fourth ventricle
  • Myelencephalon: medulla oblongata, lower fourth ventricle
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6
Q

Explain the development of the rhombencephalon

A
  • The cervical flexure demarcates the hindbrain from the spinal cord
  • The pontine flexure divides the hindbrian into the myel and metencephalon
  • Myelencephalon → medulla oblongata (gracile (medial) and cuneate (lateral) nuclei formed by neuroblasts from alar plate → marginal zone)
  • Metencephalon → pons, cerebellum
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7
Q

What are the two regions of the medulla oblongata

A
  • The caudal closed region: neuroblasts of alar plate form gracile and cuneate nuclei
  • The cranial opened region (wide and flat): motor nuclei medial to sensory nuclei. neural canal is part of the 4th ventricle
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8
Q

What signals do the neuroblasts in the alar plates receive?

A
  • They are arranged in 4 columns from medial → lateral
  • general visceral afferent neuroblasts (from viscera)
  • special visceral afferent neuroblasts (taste fibers)
  • general somatic afferent (from surface of the head)
  • special somatic afferent (from the ear)
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9
Q

What signals do the neuroblasts in the basal plates receive?

A
  • They are arranged in 3 columns from medial → lateral
  • general somatic efferent neuroblasts (going to hypoglossal nerve)
  • special visceral efferent neuroblasts (going to muscles from the pharyngeal arches)
  • general visceral efferent neuroblasts (going to neurons of the vagus and glossopharyngeal nerves)
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10
Q

Explain the formation of the choriod plexus and the CSF

A
  • The pia mater covers the external part of the fourth ventricle
  • pia mater + ependymal roof of fourth ventricle = tela choriodea
  • The pia mater proliferates making the tela choroidea invaginate into the fourth ventricle = choriod plexus
  • The choriod plexus secretes a fluid that later becomes the CSF
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11
Q

Explain the development of the pons and cerebellum

A
  • alar plates thicken to form the cerebellum and neuroblasts → marginal zone = cerebellar cortex (grey matter)
  • The pons has fibers connecting the cerebrum to the cerebellum and spinal cord
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12
Q

Explain the development of the mesencephalon

A
  • Doesn’t go thru that much change (similar to spinal cord)
  • Neuroblasts of alar platesuperior (cranial) and inferior (caudal) colliculi which are involved in the visual and auditory reflexes
  • the ventral aspect of the basal plate neuroblasts have 2 bulges → cerebral peduncles (fiber tracts form the cerebrum)
  • neural canal = cerebral aqueduct
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13
Q

Explain the development of the prosencephalon

A
  • It develops into the diencephalon and telencephalon
  • Diencephalon: caudal part of the forebrain, gives rise to epithalamus, thalamus and hypothalamus
  • Neural canal becomes the third ventricle
  • Telencephalon: cranial part of the forebrain → cerebrum
  • 2 bubble like cerebral vesiclesleft and right cerebral hemispheres → 1 C-shaped hemisphere
  • Neural canal → lateral ventricles
  • Intermediate layer cells → marginal zone = cerebral cortex
  • cerebral surface becomes convoluted → gyri & sulci
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14
Q

What two tissues develop the pituitary gland?

A
  • Hypophyseal diverticulum (roof of stomodeum)
  • Neurohypophyseal diverticulum (floor of diencephalon)
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