Embrylogy

Question 1

What is the neural tube made of ?

Answer 1

Neuroectoderm

Question 2

How does the neural tube form from the previous cord ?

Answer 2

the notochord directs the conversion of overlaying ectoderm to neuroectoderm . they form folds which fuse in the midline

Question 3

Which way does the neural tube fuse ?

Answer 3

fusion at the anterior end (Neuropore) and then after posterior end

Question 4

How does spina bifida normally occur?

Answer 4

Failure of fusion of the caudal neuropore

Question 5

Where can spina bifida occur and what is its more serious form ?

Answer 5

occur anywhere most mostly in lumbosacral region.
More serious when neural tissue is near the skin .
hydrocephalus is very common

Question 6

What happens in anencephaly?

Answer 6

failure of fusion of Anterior neuropore - foetus cannot survive

Question 7

What is Rachischisis ?

Answer 7

failure of neural fold elevation

Question 8

What 2 things help diagnose Neural tube defects?

Answer 8

Raised maternal alpha fetoprotein

USS

Question 9

What can reduce risk of NTDs?

Answer 9

Folic acid 3 months before and after conception

Question 10

How and when does the cauda equina form?

At what level does this occur?

Answer 10

At the 3rd month , vertebral column = spinal cord. after the vertebral column grows faster = spinal roots elongate to exit at the right foramen . L1

Question 11

how are forebrain structures formed?

Answer 11

Primary vesicle = Prosencephalon –> telencephalon –> Cerebral hemispheres .
Prosencephalon –> dienceohalon –> thalamus

Question 12

How are midbrain structures formed?

Answer 12

Mesencephalon –> mesencephalon –> midbrain

Question 13

How are hindbrain structures formed ?

Answer 13

Rhombencephalon –> Metencephalon –> Pons, cerebellum

Rhombencephalon –> myelencephalon –> medulla

Question 14

where does the NT fold in Brain to create the angle of the brain ?

Answer 14

Cervical flexure = between spinal cord and Rhombencephalon

cephalic flexure = between mesencephalon and rhombencephalon

Question 15

What is the function of CSF?

Answer 15

to cushion brain and spinal cord in bony case

Question 16

How does the ventricular system develop?

Answer 16

the secondary brain vesicles grow and the brain forms around the hollow tube .

Question 17

What is hydrocephalus and how can it be treated ?

Answer 17

blockage of ventricular system seen in spina bifida . treated via shunt

Question 18

How is the early neural tube layers organised from deep to superficial ?

Answer 18

Neuroepithelial = CSF secreting
Intermediate /mantle layer = neuroblasts
Marginal layer = processes

Question 19

Where are the roof and floor plates on the neural tube ?

Answer 19

Roof plate = Dorsal

Floor = Ventral

Question 20

What do the roof and floor plates go into? what are the new plates function

Answer 20

Roof = Alar plate = sensory

Floor = basal = motor

Question 21

what separates the alar and basal plate ?

Answer 21

sulcus limitans

Question 22

where are neural crest cells found ?

Answer 22

lateral border of the neural tube

Question 23

What do neural crest cells do?

Answer 23

Become displaced enter into the mesoderm , transitioning from epithelial to mesenchyme

Question 24

What are some structures that derive from neural crest cells ?

Answer 24

DRG, Sympathetic chain , Enteric ganglion , suprarenal glands .

Question 25

What can happen in neural crest defects?

Answer 25

can affetc 1 structure e.g Hirschsprung’s

or affect many structures - Digeorge’s