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Neuroanatomy > Cells & Embryology > Flashcards

Flashcards in Cells & Embryology Deck (43):
1

HOw many weeks post-fertilization does the neural plate begin to form?

3rd week

2

What germ layer forms the neural plate?

ectoderm

3

What cavity is the ectoderm continuous with? The endoderm?

ectoderm continuous with amniotic cavity (above)
endoderm continuous with yolk sac (below)

4

What structure floors the amniotic cavity in the 3rd week?

embryonic disc

5

By what day does the neural groove and neural folds begin to form?

day 18

6

When do the neural folds approach each other?

day 20

7

When do the neural folds fuse across the midline/form tube which then sinks below surface ectoderm?

day 21

8

What day does the anterior neuropore close?

day 24

9

What day does the posterior neuropore close?

day 26

10

From what germ cell layer are neural crest cells dervied?

ectoderm

11

Neurons that fall in dorsal root ganglion are what functional and morphological type?

sensory
pseudounipolar

12

What two cranial nerves derive from placodes? Why?

CN I and CN VIII
bipolar neurons
special senses different from general sensation

13

What cavity is continuous with the anterior neuropore?

amniotic cavity

14

What cell type is the single layer of ectodermal cells lining the neural tube cavity?

pseudostratified columnar epithelium

15

Describe how the neural tube goes from being lined by a single cell layer to three cell layers

ependymal layer surrounded by cell free marginal layer
cells in ependymal layer divide until they migrate from central canal guided by radial glial --> form mantle layer
now there is a mantle layer in between ependymal layer and marginal layer

16

Which cell layer is the precursor of gray matter?

intermediate cell layer (mantle cell layer)

17

Which cell layer is the precursor of white matter ?

marginal cell layer

18

What is lined by ependymal cells in the adult

central canal and ventricles

19

What week is the sulcus limitans formed? What does it separate?

4th week
separates alar plate and basal plate

20

What layer differentiates into the alar and basal plates? When?

intermediate (mantle) cell layer
during 6th week

21

What is the fate of the alar plate? basal plate?

alar - dorsal horn - sensory
basal - ventral horn - motor

22

What zone lies between the alar plate and basal plate? What is its fate? function?

intermediate zone - intermediate gray
interneurons connecting sensory with motor neurons
autonomic elements (S&PS)

23

What comprises the three vesicle stage of the brain? When does this occur?

prosencephalon
mesencephalon
diencephalon
during 4th week

24

What comprises the five vesicle stage of the brain? When does this occur?

during 5th week, by 6th week
prosencephalon --> telencephalon & diencephalon
mesencephalon --> mesencephalon
diencephalon --> metencephalon & myelencephalon

25

By what week is the pontine, cervical and cephalic flexures formed?

by week 6

26

The telecephalon becomes the __ in adult brain

cerebral hemispheres & basal ganglia

27

The diencephalon becomes the ___ in adult brain

thalamus, hypothalamus, subthalamus, epithalamus

28

The mesencephalon becomes the ___ in the adult brain

mesencephalon

29

THe metencephalon becomes the ___ in the adult brain

pons, cerebellum

30

The myelencephalon becomes the ___ in adult brain

medulla oblongata

31

When do we start to see sulci? Gyri?

6 months - sulci
9 months - gyri

32

What is spina bifida?

failure of the full formation of the vertebrae (bony defect)

33

What is spina bifida occulta?

neural arch in vertebrae fails to form
most common
doesnt involve underlying neural tissue
usually lumbar spine
hairy patch, small dimple

34

What is spina bifida aperta?

open
can occur with meningocele, myelomeningocele, myeloschisis

35

What is meningocele?

cyst that develops off the dimple seen in occulta
may be filled with CSF but does not occur neural elements

36

What is myelomeningocele?

elements of the spinal cord, spinal nerves are extravasated into the cyst
occasionally seen with hydrocephalus

37

What is myeloschisis

folds dont fuse together to form tube
neural plate elements remain continuous with surface ectoderm

38

What is encephalocele?

bony defect in occipital bone of skull
cyst is formed occasionally with the inclusion of the cerebral hemispheres at posterior pole

39

What is anencephaly?

anterior neuropore fails to close
middle to caudal part of brainstem and brain fails to develop
brain may be exposed at surface and may simply be covered by a small amount of tissue
condition is not survivable beyond 30 days

40

What is the metabolic and synthetic region of the neuron?

cell body (soma)

41

Are inhibitory synapses symmetric or asymmetric?

symmetric

42

Are excitatory synapses symmetric or asymmetric?

asymmetric

43

What are the most common types of synapses

axo-dendritic
axo-somatic