Neurology--Embryology -- First Aid

Question 1

Notochord induces the overlying ___ to differentiate into ___ and form the ____.

Answer 1

ectoderm, neuroectoderm, neural plate

Question 2

The neural plate, differentiated by the notochord, gives rise the two populations of cells…

Answer 2

1) those forming the neural tube 2) neural crest cells

Question 3

Name the three primary vesicles of the developing brain

Answer 3

Forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombenecphalon)

Question 4

The forebrain (prosencephalon) is one of the three primary vesicles in brain development. What secondary structures does the forebrain give rise to?

Answer 4

Telencephalon (superior; cerebral hemispheres + lateral ventricle) and Diencephalon (just below; thalamus, third ventricle)

Question 5

The midbrain (mesencephalon), one of the thee primary vesicles in brain development, gives rise to what secondary structure(s)?

Answer 5

The mesencephalon! (stays same name in secondary structure) Gives rise to midbrain (wall) and aqueduct (cavity)

Question 6

The hindbrain (rhombencephalon) is one of the three primary vesicles in brain development. What secondary structures does the hindbrain give rise to?

Answer 6

The metencephalon (pons, cerebellum, upper part of fourth ventricle) and the myelencephalon (medulla, lower part of fourth ventricle)

Question 7

CNS neurons (and oligodendroglia, astrocytes, and ependymal cells) originate from what?

Answer 7

neuroectoderm

Question 8

PNS neurons (and Schwann cells) originate from what?

Answer 8

neural crest cells

Question 9

Microglia (like Macrophages) originate from what?

Answer 9

Mesoderm

Question 10

Neural tube defects, definition

Answer 10

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.

Question 11

spina bifida occulta

Answer 11

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.

Question 12

meningocele

Answer 12

Neural tube defect.

meninges (but not spinal cord) herniate through spinal canal defect. Normal AFP

Question 13

meningomyelocele

Answer 13

Neural tube defect.

meninges and spinal cord herniate through spinal canal defect

Question 14

anencephaly

Answer 14

A Forebrain anomaly.

Malformation of anterior neural tube resulting in no forebrain, open calvarium (“frog like appearance”)

Question 15

holoprosencephaly

Answer 15

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.

Question 16

Chiari II (Arnold-Chiari malformation)

Answer 16

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

Question 17

Dandy-Walker

Answer 17

posterior fossa malformation
agenesis (no formation) of cerebellar vermis with cystic enlargement of 4th ventricle. Associated with hydrocephalus and spina bifida.

Question 18

Syringomyelia

Answer 18

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)

Question 19

Chiari I malformation

Answer 19

associated with syringomyelia.
>3-5mm cerebellar tonsillar ectopia; congenital, usually asymptomatic in childhood, manifest with headaches and cerebellar symptoms.

Question 20

Tongue development: anterior ⅔ formed by what?

Answer 20

1st and 2nd branchial arches (sensation via CN V3, taste via CN VII)

Question 21

Tongue development: posterior ⅓ formed by what?

Answer 21

3rd and forth branchial arches (sensation and taste via CN IX, extreme posterior by X)

Question 22

Motor innervation of the tongue?

Answer 22

CN XII

Question 23

What cranial nerves supply the tongue with taste, pain, and motor?

Answer 23

taste – CN VII, IX, X (solitary nucleus)
pain – CN V3, IX, X
motor – CN XII