Nervous System Embryology

Question 1

Nervous System Embryology ~ from

Answer 1

ectoderm (neural + epidermis)

Question 2

Neuroblasts + Glioblasts ~ from

Answer 2

Ventricular Zone Neuroepithelial Cells and Migrate Out

Question 3

Neuroblasts: form all

Answer 3

neurons in the CNS

Question 4

Glioblast: form

Answer 4

radial glial cells, astrocytes, oligodendrocytes, ependymocytes (choroid), tanycytes

Question 5

Radial Glial Cells: form before

Answer 5

neuroblasts –> neurons; other glial cells form after

Occurs because radial glial cells serve as “guide wires” for neuron migration

Question 6

Microglia: from

Answer 6

monocyte linage in blood and migrate to CNS in 3rd Week (before vessels)

Question 7

Neural Tube Development ~ Ectodermal Tube ~3rd Week:

Answer 7

notochord initiates long. thickening of ectoderm —> neural plate

Question 8

Neural Tube Development Folding:

Answer 8

neural plate folds in (posterior surface) —> neural folds form w/ neural crest cells on top

Question 9

Neural Tube Development Fuse:

Answer 9

folds approach each other —> fuse —> neural tube forms

Question 10

Rostral Neural Tube: develops into

Answer 10

brain

Question 11

Caudal Neural Tube: develops into

Answer 11

spinal cord

Question 12

Alar Plate:

Answer 12

develops into sensory nuclei/nerves, including dorsal horn (spinal cord), DRG and brainstem nuclei

Question 13

Basal Plate:

Answer 13

develops into motor nuclei/nerves, including ventral horn (spinal cord) and brainstem nuclei

Question 14

Sulcus Limitans:

Answer 14

useful landmark in developing spinal cord, but remains landmark in adult brainstem

Question 15

Brain Development ~ occurs

Answer 15

4th Week (Rostral Neural Tube - makes sense 1 week later)

Question 16

Brain Development ~ 4th Week:

Answer 16

differential enlargements (vesicles) and bends (flexure) of tube

Question 17

1° Vesicles:

Answer 17

prosencephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon
(hindbrain; fuses with spinal neural tube)

Question 18

~5th Week: formation of

Answer 18

5x 2° vesicles (2° enlargements of 1° vesicles)

Question 19

Prosencephalon: forms

Answer 19

telencephalon & diencephalon

Question 20

Telencephalon: forms

Answer 20

cerebral hemispheres + deep structures

Question 21

Diencephalon: forms

Answer 21

thalamus, hypothalamus, subthalamus

Question 22

Mesencephalon:

Answer 22

remains undivided as “midbrain”

Question 23

Rhombencephalon: forms

Answer 23

metencephalon & myelencephalon

Question 24

Metencephalon: forms

Answer 24

pons & cerebellum

Question 25

Myelencephalon:

Answer 25

medulla

Question 26

Spinal Cord Development 3 Month Fetus:

Answer 26

end of cord (conus) ends at end of spinal column

Question 27

Spinal Cord Development 6 Month Fetus:

Answer 27

conus ends at S1

Question 28

Spinal Cord Development 3. 9 Month Fetus:

Answer 28

conus ends at L3

Question 29

Spinal Cord Development Adult:

Answer 29

conus ends at L2 (dural sheath ends at S2)

Question 30

Anterior Pore Closure Failure —>

Answer 30

Anencephaly / Encephalocele

Question 31

Posterior Pore Closure Failure —>

Answer 31

Spina Bifida / Meningocele / Myelomeningocele

Question 32

Folic Acid: deficiency —>

Answer 32

failure of neural tube closure

Question 33

ɑ-Fetal Protein: closure fail —>

Answer 33

↑ ɑ-fetal protein in amniotic fluid

Question 34

xPosterior Pore Closure - Defects occur @ any

Answer 34

level

Question 35

Spina Bifida Occulta: failure of

Presentation: tuft of hair over area / sinus tract

Answer 35

mesodermal cells to form vertebra around spinal cord - No bony dorsal vertebra, no neuro symptoms, no meningeal involvement
Presentation: tuft of hair over area / sinus tract

Question 36

Spina Bifida Aparta:

Answer 36

+meningeal/spinal cord involvement, +neuro symptoms, ↑severe

Question 37

Spina Bifida Aparta: With Meningocele:

Answer 37

meninges outpouch

Question 38

Spina Bifida Aparta: With Myelomingocele:

Answer 38

meninges + spinal cord/filum terminale outpouch

Question 39

Arnold-Chiari Malformations Definition:

Answer 39

displacement of cerebellar tonsils below foramen magnum

Question 40

Chiari Type I Malformation:

Answer 40

just displaced cerebellar tonsils

Question 41

Chiari Type II Malformation:

Answer 41

displaced tonsils + cervical/occipital encephalocele

Question 42

Orientation of Brain: Rostral —> Caudal

Answer 42

Rostral —> Caudal
Forebrain –> Mid –> Hind –> Spinal Cord –>
Nerve Root –> Peripheral Nerve —> NMJ

Question 43

Coronal Cut:

Answer 43

dorsal –> ventral; same plane as if you imagined a crown slicing down into brain

Question 44

Horizontal Cut:

Answer 44

|| to the ground, aka axial cut

Question 45

Sagittal Cut:

Answer 45

anterior –> posterior; follows calvaria sagittal suture

Question 46

Gray Matter CNS:

Answer 46

any accumulation of neuronal cell bodies (allow ↑SA/# with grooves (sulci) / ridges (gyri))
Includes: Cortical Layer, Deep Structures, & Brain Stem:

Question 47

Cortical Layer:

Answer 47

covering forebrain / cerebellum

Question 48

Deep Structures:

Answer 48

forebrain, basal ganglion, limbic system

Question 49

Brain Stem:

Answer 49

intrinsic pathways, cranial nerve nuclei

Nuclei: collection of nerve cell bodies in CNS (same as ganglion in PNS)

Question 50

White Matter:

Answer 50

sum of all fiber tracts (tract = bundle of axons; same as nerve in PNS)

Question 51

Contrast Brain Gray & White matter w/Spinal Cord:

Answer 51

note core is gray matter (nuclei) with surrounding white matter