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Nervous System: Unit I > Embryology I > Flashcards

Flashcards in Embryology I Deck (12)
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1
Q

Primary axes of the central nervous system

A
  • rostral (“towards the nose”) vs. caudal (“towards the tail”)
  • ventral vs. dorsal
    • below the cephalic flexure
      • ventral = “towards the stomach”
      • dorsal = “towards the back”
    • above the cephalic flexure
      • ventral = towards the chin
      • dorsal = towards the top of the head
2
Q

Cephalic flexure definition

A
  • initially straight neural tube ==> 80o turn during development between the brain and brainstem (=diencephalon & mesencephalon)
3
Q

Planes used to discuss CNS

A
  • horizontal/transverse/cross-section
  • coronal
  • sagittal
4
Q

Primary cerebral vesicles

A
  • proencephalon (forebrain) = most rostral
  • mesencephalon (midbrain)
  • rhombencephalon (hindbrain) = most caudal
  • 3 primary cerebral vesicles ==> 5 secondary cerebral vesicles
5
Q

Secondary cerebral vesicles (+ primary vesicle origins)

A
  • prosencephalon ==> telencephalon (paired enlargements cranially) & diencephalon (more caudal)
  • mesencephalon ==> mesencephalon
  • rhombencephalon ==> metencephalon (more rostral) & myelencephalon (more caudal)
6
Q

Secondary vesicles ==> Adult brain structures

A
  • telencephalon ==> cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei)
  • diencephalon ==> diencephalon: thalamus, hypothalamus, epithalamus
  • mesencephalon ==> brain stem: midbrain
  • metencephalon ==> brain stem: pons & cerebellum
  • myelencephalon ==> brain stem: medulla
7
Q

Secondary vesicles ==> adult neural canal regions

A
  • telencephalon ==> lateral ventricles
  • diencephalon ==> third ventricle
  • mesencephalon ==> cerebral aqueduct
  • metencephalon ==> fourth ventricle
  • myelencephalon ==> cerebral canal
8
Q

Rhombomere location/development

A
  • rhomboencephalon = 8 morphologically distinct rhombomeres
    • r1 = posterior to mesencephalon
    • r8 = anterior to spinal cord
    • rhombomeres = similar size/number of cells
  • each rhombomere develops uniquely ==> different morphologies, axonal trajectories, NT synthesis, etc.
    • HOX genes expressed differently ==> differentiation
9
Q

Common dorsoventral patterning w/in neural tube

A
  • dorsal = sensory
  • ventral = motor
10
Q

Neural tube development of dosoventral patterning

A
  • neural tube develops sulcus limitans = separates ventral and dorsal population
    • ventral = “basal plate”
    • dorsal = “alar plate”
  • @ basal plate ==> axons grow out to myotomes
  • @ alar plate ==> dorsal root ganglia (sensory neurons from neural crest cells) grow to innervate neurons
11
Q

Modifications of dorsoventral pattern @ midbrain, pons, medulla, & spinal cord

A
  • development of dorsoventral patterning is unique to each section of the midbrain
12
Q

Basic scheme of dorsoventral patterning of prosencephalon

A
  • Before the telencephalic vesicles the rostral neural tube (forebrain) develops regionally restricted sonic hedgehog DV markers,
  • DV markers ==> three discrete proliferative zones.
    • cortex (dorsally)
    • lateral ganglionic eminence
    • medial ganglionic eminence