Embryology

Question 1

at what week does the nervous system begin to develop

Answer 1

week 3

Question 2

why is the nervous system not fully functional after birth

Answer 2

as the neurones are not fully myelinated

Question 3

describe the formation of the neural tube from gastrulation

Answer 3

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

Question 4

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

Answer 4

anterior and posterior neuropore

Question 5

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

Answer 5

anencephaly - without a brain

Question 6

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

Answer 6

spina bifida

Question 7

what is spina bifida

Answer 7

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

Question 8

true or false spina bifida is often associated with hydrocephalus

Answer 8

true as it could lead to CSF circulation difficulties

Question 9

what is Rachischisis

Answer 9

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

Question 10

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

Answer 10

alpha fetoprotein

Question 11

what are the 3 types of spina bifida

Answer 11

occulta, meningocele, myelomeningocele

Question 12

what is spina bifida occulta

Answer 12

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

Question 13

what is spina bifida meningocele

Answer 13

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

Question 14

what is spina bifida myelomeningocele

Answer 14

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

Question 15

at what level does spina bifida usually occur

Answer 15

L5-S1

Question 16

how does folic acid prevent neural tube defects

Answer 16

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

Question 17

at what spinal level does the cauda equina begin

Answer 17

L1

Question 18

why does the cauda equina develop

Answer 18

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

Question 19

at what level should a lumbar puncture be administered and why

Answer 19

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

Question 20

name some functions of neural crest cells

Answer 20

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

Question 21

what is Hirschsprung’s disease

Answer 21

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

Question 22

what is diGeorges syndrome

Answer 22

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

Question 23

what are flexures

Answer 23

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

Question 24

what are the 2 flexures

Answer 24

cephalic - bend in the midbrain

cervical - bend in the hindbrain-spinal cord junction

Question 25

what are the 3 dilations of the neural tube called

Answer 25

forebrain - prosencephalon midbrain - mesencephalon hindbrain - rhombencephalon

Question 26

what are the primary brain vesicles

Answer 26

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

Question 27

what are the secondary brain vesicles

Answer 27

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

Question 28

what are the 5 secondary brain vesicles called

Answer 28

``` telencephalon dincephalon mesencephalon metencephalon myelencephalon ```

Question 29

which secondary brain vesicle do the cerebral hemisphere develop from

Answer 29

telencephalon

Question 30

which secondary brain vesicles does the thalamus develop from

Answer 30

diencephalon

Question 31

which secondary brain vesicle does the midbrain develop from

Answer 31

mesencephalon

Question 32

which seoncdary brain vesicle does the cerebellum and pons develop from

Answer 32

mesencephalon

Question 33

which secondary brain vesicle does the medulla oblongata develop from

Answer 33

myelencephalon

Question 34

what cells produce CSF

Answer 34

choroid plexus cells found in the ventricles

Question 35

what are the ventricles

Answer 35

fluid filled spaces in the CNS

Question 36

how much CSF is produced per day

Answer 36

600 ml

Question 37

what is the function of CSF

Answer 37

to cushion the brain and spinal cord

Question 38

what connects the lateral ventricles to the 3rd ventricles

Answer 38

intraventricular foramen

Question 39

what connects the 3rd ventricle to the 4th ventricle

Answer 39

cerebral aqueduct

Question 40

how does CSF drain

Answer 40

drains through the ventricles to the 4 ventricle where it can then drain through the central canal or the lateral and medial apertures. from the apertures it goes into the subarachnoid space where its reabsorbed by arachnoid granulations in the superior sagittal sinus to join the venous circulation

Question 41

what is hydrocephalus

Answer 41

where there is a build up of CSF in the ventricles due to a mismatch between CSF production and drainage

Question 42

what may cause hydrocephalous

Answer 42

tumour, infection, stenosis, spina bifida

Question 43

how is hydrocephalous treated

Answer 43

ventricular-peritoneal shunt. this is where a shunt goes from the ventricle to the abdominal cavity so that CSF is drained in the abdomen instead

Question 44

what are the disadvantages of ventricular-peritoneal shunts

Answer 44

infection | may outgrow them in the case of children