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Phase 1 - S4 Nervous System > Embryology > Flashcards

Flashcards in Embryology Deck (44)
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1

at what week does the nervous system begin to develop

week 3

2

why is the nervous system not fully functional after birth

as the neurones are not fully myelinated

3

describe the formation of the neural tube from gastrulation

gastrulation produces a notochord in the mesoderm
this causes the overlying ectoderm to differentiate into neuroectoderm. this region then thickens and theres elevation of the lateral edges which come together and fuse to form the neural tube

4

what are the ends of the neural tube called before they close

anterior and posterior neuropore

5

what do cranial defects in the failure of the neural tube to close cause

anencephaly - without a brain

6

what do caudal defects in the failure of the neural tube to close cause

spina bifida

7

what is spina bifida

when the neural tube fails to fuse leading to problems with the spinal cord and closure of the spinal vertebrae itself

8

true or false spina bifida is often associated with hydrocephalus

true as it could lead to CSF circulation difficulties

9

what is Rachischisis

failure of neural fold elevation so the neural tube never actually forms

10

what protein is often raised in the mothers blood when there is a neural tube defect

alpha fetoprotein

11

what are the 3 types of spina bifida

occulta, meningocele, myelomeningocele

12

what is spina bifida occulta

where there is no protrusion/lumps of CSF or anything only a failure of the posterior vertebral arch to fuse

13

what is spina bifida meningocele

where meninges and CSF herniates through the region of the posterior vertebral arch which failed to fuse

14

what is spina bifida myelomeningocele

where meninges, CSF and spinal cord all herniate through the poorly fused vertebral column giving neurological defects

15

at what level does spina bifida usually occur

L5-S1

16

how does folic acid prevent neural tube defects

helps the epithelial folds to fuse together to close the neural tube

17

at what spinal level does the cauda equina begin

L1

18

why does the cauda equina develop

the vertebral column begins to grow faster than the spinal cord and so the spinal roots must elongate so that they can exit at their respective vertebral foramen

19

at what level should a lumbar puncture be administered and why

L3/4 as the spinal cord is finished and it is at the level of the cauda equina so there is less risk for neurological damage

20

name some functions of neural crest cells

endocardial cushions, dorsal root ganglion, sympathetic ganglion, Schwann cells

21

what is Hirschsprung's disease

where the neural crest cells fail to develop into the enteric ganglion

22

what is diGeorges syndrome

where the neural crest cells fail to migrate properly leading to problems with the thymus, thyroid, face and CVS

23

what are flexures

a change in the axis of the nervous system as the neural tube grows too much for the room it has and so it must fold

24

what are the 2 flexures

cephalic - bend in the midbrain
cervical - bend in the hindbrain-spinal cord junction

25

what are the 3 dilations of the neural tube called

forebrain - prosencephalon
midbrain - mesencephalon
hindbrain - rhombencephalon

26

what are the primary brain vesicles

the 3 areas of dilation of the cranial end of the neural tube when the tube has closed

27

what are the secondary brain vesicles

the 5 divisions resulting from the change in shape from the 3 primary brain vesicles

28

what are the 5 secondary brain vesicles called

telencephalon
dincephalon
mesencephalon
metencephalon
myelencephalon

29

which secondary brain vesicle do the cerebral hemisphere develop from

telencephalon

30

which secondary brain vesicles does the thalamus develop from

diencephalon