A 4 NeuroEmbryology

Question 0

What are the 5 Neural Tube defects?

Answer 0

• spina bifida occulta – defect limited to vertebra.
• meningocoele (involves meninges)
• meningomyelocoele –(involves meninges and nervous tissue)
• craniorachischisis – (most severe – neural tube not fully rolled up
• Anencephaly- defective closure of anterior neuropore.

Question 1

Prosencephalon produces what brain parts?

Answer 1

Tel: Cerebral cortex, basal nuclei, limbic lobe (lateral ventricles)
Di: Thalamus, hypothalamus, epithalamus

Question 2

Mesencephalon produces what brain parts?

Answer 2

Midbrain (cerebral aqueduct)

Question 3

Rhombencephalon produces what brain parts?

Answer 3

Met: Cerebellum, Pons (4th ventricle)
Myel: Medulla (4th ventricle)

Question 5

Lissencephaly is what?

Answer 5

Smoooth brain due to a Migration problem. (seizures and death in infancy)

Question 5

Polymicrogyria is what?

Answer 5

Numerous small gyri that can be localized or be the whole brain. Migration problem causing Retardation and epilepsy.

Question 6

Pachygyria is what?

Answer 6

Thick brain. Migration prob. (Lesser degree of lissencephaly, you can live)

Question 7

Agenesis of corpus callosum is what?

Answer 7

May be clinically silent, or learning probs. problems with axon extension.

Question 8

Cortical Heterotopia is what?

Answer 8

Normal neurons in abnormal locations. Migration prob. (focal seizures)

Question 9

What signals myelination to occur?

Answer 9

Action potentials and chemical signals on axon surfaces

Question 10

Cocaine does what to the brain?

Answer 10

Impairs synaptic reuptake of monoamine neurotransmitters. (serotonin, dopamine, norepi, epi) It prevents normal synapse formation in neurons if in-utero.

Question 11

Myelencephalon produces what brain parts?

Answer 11

Medulla (myelencephalon is a subsection of rhombencephalon)

Question 12

Metachromatic leukodystrophy is what?

Answer 12

Myelin fails to form in CNS and PNS. Normal development for a while, then the child regresses.

Question 13

when does the nervous system first appear during gestation?

Answer 13

3 weeks

Question 14

what causes dorsal patterning of the spinal cord?

Answer 14

BMP gradient. (high BMP forms the dorsal aspect)

FGF and Wnt are also posteriorizing signals.

Question 15

what secretes BMP 4?

Answer 15

the overlying ectoderm

Question 16

which molecules are antagonists to BMP?

Answer 16

Noggin and chordin. (these are secreted by the notochord)

Question 17

What mainly patterns the formation of the ventral part of the spinal cord?

Answer 17

SHH released by the notochord. (considered to be the dorsal mesoderm, it turns middle of neural plate into floor plate and causes the forebrain to split into 2 hemispheres)

Question 18

what is the floor plate?

Answer 18

ventral most part of spinal cord

Question 19

what is the basal plate?

Answer 19

the more ventrally located area of the spinal cord that carries the autonomic AND somatic motor neurons. Forms the ventral horn.

Question 20

what is the sulcus limitans?

Answer 20

the sulcus that divides the ventral from the dorsal spinal cord. It extents the entire length.

Question 21

What is the alar plate?

Answer 21

It contains the sensory and coordinating neurons. Forms the dorsal horn.

Question 22

what is the roofplate?

Answer 22

the most dorsal part of the spinal cord

Question 23

Neural crest cells become?

Answer 23

sensory neurons outside CNS
postsynaptic neurons for autonomics
chromaffin cells (adrenal medulla)
melanocytes
schwan cells
satellite cells
Jaw, skull,
meninges

Question 24

what is a neurocristopathy?

Answer 24

defect in NCC migration. Often causes cleft palate, facial malformations, hirschprung disease, etc.

Question 25

what is the thickened area of ectoderm lateral to the NCC's and neural plate called? what do they do?

Answer 25

Neurogenic placodes. They give rise to neurons and glia.

Question 26

when does the neural tube close?

Answer 26

28 days. (first at the anterior neuropore then at the posterior neuropore)

Question 27

What is holoproencephaly? What causes it?

Answer 27

A defect that prevents the separation of the two hemispheres, absence of corpus callosum, fusion of the thalami, and often cyclopia. Caused by a defect in SHH

Question 28

what is septo-optic dysplasia?

Answer 28

a milder form of haloproencephaly. Incomplete separation of the proencephalon, absence of septum pellucidum, optic nerve hypoplasia. blind, mentally retarded, endocrine problems.

Question 29

when are most neurons formed?

Answer 29

2-5 months of gestation.

Question 30

what are the four radial layers of the spinal cord called from inside to outside?

Answer 30

1) ependymal layer (in contact with lumen) 2) subventricular zone (where mitosis takes place) 3) mantle zone (future grey matter of spinal cord) 4) marginal zone (future white matter of spinal cord) Note: the mantle zone is where the neurons migrate after mitosis.

Question 31

What are some characteristics of Fetal alcohol syndrome?

Answer 31

micorcephaly impaired learing seizures (due to neuron proliferation problem)

Question 32

what is hemimegacephaly?

Answer 32

``` one side of brain is larger than other side due to an error in brain cell proliferation signals. large heads seizures mental retardation contralateral hemiparesis ```

Question 33

In the brain, after the cells have undergone mitosis in the subventricular zone, they migrate to their correct positions following what?

Answer 33

radial glia. They extend from the ventricle to the cortical surface.

Question 34

which neruons are the first to arrive at the cerebral cortex? last to arrive?

Answer 34

first are the layer 6, last are layer 1. They have to migrate through each other from 6 to 1.

Question 35

Why is the brain formed with gyri and sulci?

Answer 35

to increase surface area.

Question 36

Once in location, immature neurons link to their targets by?

Answer 36

cell adhesion molecules electrical currents chemical signals

Question 37

what happens with agenesis of the corpus callosum?

Answer 37

often it is silent, but it can result in learning disturbances.

Question 38

when does myelination occur?

Answer 38

begins in third trimester and continues into adulthood.

Question 39

T/F The weight of a babies brain is 3% of their total weight?

Answer 39

true. Adults are only 2%

Question 40

What is a neuroteratogen?

Answer 40

exogenous factors such as chemicals, radiation, etc. that cause neuronal defects of abnormalities.

Question 41

T/F Gyrification of the brain continues after birth?

Answer 41

True

Question 42

The sulcus limitans divides which two structures?

Answer 42

the basal plate (ventral) form the alar plate (dorsal)

Question 43

What are the 4 diseases that are caused by migration problems?

Answer 43

Cortical heterotropia Lissencephaly Pachygyria Polymicrogyria