Neurology--Embryology -- First Aid Flashcards
Notochord induces the overlying ___ to differentiate into ___ and form the ____.
ectoderm, neuroectoderm, neural plate
The neural plate, differentiated by the notochord, gives rise the two populations of cells…
1) those forming the neural tube 2) neural crest cells
Name the three primary vesicles of the developing brain
Forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombenecphalon)
The forebrain (prosencephalon) is one of the three primary vesicles in brain development. What secondary structures does the forebrain give rise to?
Telencephalon (superior; cerebral hemispheres + lateral ventricle) and Diencephalon (just below; thalamus, third ventricle)
The midbrain (mesencephalon), one of the thee primary vesicles in brain development, gives rise to what secondary structure(s)?
The mesencephalon! (stays same name in secondary structure) Gives rise to midbrain (wall) and aqueduct (cavity)
The hindbrain (rhombencephalon) is one of the three primary vesicles in brain development. What secondary structures does the hindbrain give rise to?
The metencephalon (pons, cerebellum, upper part of fourth ventricle) and the myelencephalon (medulla, lower part of fourth ventricle)
CNS neurons (and oligodendroglia, astrocytes, and ependymal cells) originate from what?
neuroectoderm
PNS neurons (and Schwann cells) originate from what?
neural crest cells
Microglia (like Macrophages) originate from what?
Mesoderm
Neural tube defects, definition
neuropores fail to fuse (4th week) resulting in a persistent connection between amniotic cavity and spinal canal. (Note increased alpha-fetoprotein in amniotic fluid and maternal serum; increased acetylcholinesterase in amniotic fluid confirmatory.
spina bifida occulta
Neural tube defect.
Failure of bony spinal canal to close, but no structural herniation. Associated with tuft of hair or dimple, usually at lumbar level.
meningocele
Neural tube defect.
meninges (but not spinal cord) herniate through spinal canal defect. Normal AFP
meningomyelocele
Neural tube defect.
meninges and spinal cord herniate through spinal canal defect
anencephaly
A Forebrain anomaly.
Malformation of anterior neural tube resulting in no forebrain, open calvarium (“frog like appearance”)
holoprosencephaly
Forebrain anomaly.
failure of left and right hemispheres to separate; usually occurs during weeks 5-6. Moderate form = cleft lip/palate, most severe form results in cyclopia.
Chiari II (Arnold-Chiari malformation)
Posterior fossa malformation.
significant herniation of cerebellar tonsils and vermis through foramen magnum with aqueductal stenosis and hydrocephalus. Often present with lumbosacral myelomeningocele and paralysis below the defect
Dandy-Walker
posterior fossa malformation
agenesis (no formation) of cerebellar vermis with cystic enlargement of 4th ventricle. Associated with hydrocephalus and spina bifida.
Syringomyelia
cystic cavity (syrinx) within the spinal cord (if central canal –> hydromyelia). Crossing anterior spinal commissureal fibers are typically damaged first. “Cape like” bilateral loss of pain and temperature sensation in upper extremities (fine touch [dorsal column] preserved)
Chiari I malformation
associated with syringomyelia.
>3-5mm cerebellar tonsillar ectopia; congenital, usually asymptomatic in childhood, manifest with headaches and cerebellar symptoms.
Tongue development: anterior ⅔ formed by what?
1st and 2nd branchial arches (sensation via CN V3, taste via CN VII)
Tongue development: posterior ⅓ formed by what?
3rd and forth branchial arches (sensation and taste via CN IX, extreme posterior by X)
Motor innervation of the tongue?
CN XII
What cranial nerves supply the tongue with taste, pain, and motor?
taste – CN VII, IX, X (solitary nucleus)
pain – CN V3, IX, X
motor – CN XII
