C8: Normal Fetal Brain Anatomy Flashcards by M B

what does the CNS develop from?

the neural plate which is a thickened area of the ectoderm

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when does the CNS develop

4.5 wks

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when do the cranial and caudal end close

cranial: 38 LMP
caudal: 40 LMP

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what areas are the most common for neural tube defects

rostral and caudal end

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the rostral portion of the neural tube differentiates into what 3 parts

prosencephalon: forms the forebrain
mesencephalon: forms the midbrain
rhombencephalon: forms the hindbrain

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what does the forebrain divide into

telencephalon which form the cerebral hemispheres

- diencephalon which forms the thalamus and hypothalamus

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describe the mesencephalon

forms the midbrain
smallest part of the brain
forms the cerebral peduncles
anterior to the aqueduct of sylvius

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describe the rhombencephalon…

What does it form?

-forms the hind brain, which includes:
+cerebellum and pons (metencephalon)
+medulla oblongata (myelencephalon)

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Where is the cerebellum and pons/metencephalon located?

pons is located B/w the midbrain and the medulla oblongata

- pons connects the cerebrum to the cerebellum

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Where is the medulla oblongata/myelencephalon located?

What is its function

extends from the pons to the spinal cord

- regulated HR, respiratory rhythm and BP

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Which structure in the fetal brain is the first to be seen? When is in seen in wks

The rhombencephalon

@ 7-8 wks

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What function is the cerebrum responsible for?

Learned behaviour and personality

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What lobes is the cerebrum composed of?

2 frontal lobes
2 parietal
2 occipital
2 temporal
2 insula lobes

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What are the 2 insula lobes responsible for

Motor and sensory function

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List what each of the lobes of the cerebrum are responsible for

Frontal: personality and voluntary movement

Parietal: peripheral sensory

Temporal: small, taste, hearing

Occipital; vision

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Where is the insula located

On the medial inside of the brain

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What are the ventricles?

Which structure are they continuous with and what do they contain?

4 connecting cavities in the cerebral hemispheres of the brain

Continuous with the spinal cord cavity…. contain CSF and choroid plexus

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Is the 3rd ventiricle usually seen on US?

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What is the ventricular system composed of

Lateral ventricles
foramen of monro
3rd ventricle
aqueduct of Sylvius
4th ventricle
foramen of magendie and luschka
spinal cord

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What are the other terms for the foramen of monro and aqueduct of sylvius

Foramen: Interventricular foramen

Aqueduct: cerebral aqueduct

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Describe the foramen of magendie, where is it located?

medial aspect of 4th ventricle

- connects to the spinal cord

Describe the foramen of luschka, where is it located?

2 foramen
located on lateral aspect of 4th ventricle
connects w/ meninges of brain

Where are the lateral ventricles located? Describe their shape

-in the cerebral hemispheres

-largest ventricle that has a body and 3 horns…
+anterior/frontal horns
+posterior/occipital horns
+inferior/temporal horns

What is the trigone/atria

Junction where the body, temporal and occipital horns meet

Does the anterior/frontal horn have any choroid? Where is it located?

No... anterior to the foramen of monro

Where is the3rd ventricle located? Describe its shape. Which other ventricles does it communicate with

- b/w the thalami and inferior to the corpus callosum - thin slit shape - communicates with the lateral ventricles through the foramen of monro and the 4th ventricle via the aqueduct of sylvius

Where is the 4rd ventricle located? Describe its shape. Which other structures does it communicate with

- w/in the brain stem and anterior to the cerebellum - communicates with central canal of the spinal cord through the foramen of magendie and the subarachnoid spaces of the meninges through the foramen of luschka

What do the choroid plexus produce and where are they located

Produce CSF - Located in the body of the lateral ventricles - roof of 3rd ventricles - superior side of 4th ventricles

Up until how many wks do we see the germinal matrix What does the germinal matrix produce

28 wks Produces neurons

What is the corpus callosum Where is it located?

A bridge of white matter nerve fibers that connect the right and left cerebral hemispheres -deep in the longitudinal fissure

What are the 4 parts of the corpus callosum

Rostrum Genu Body Splenium

If the CSP isn’t present, which structure is commonly missing as well

Corpus callosum

What are the meninges? | What are the layers from inner to outer?

Protective areas of the brain that surround the brain and enter the sulcui and gyri 1. Pia matter 2. Arachnoid mater 3. Dura mater

What are the sulci and gyri

Gyri: convolutions Sulci: grooves

Where is the CSP located and what structures does it separate

Anterior and superior to the thalamus -separates the anterior horns of the lateral ventricles

If you’re showing the equal sign for the CSP what structure are you actually showing

Columns of the fornix

Where is the cavum vergae located and when does it close

- @ the posterior tip of the CSP | - closes @ 26 wks

What are the function of the sulci?

Allow for more cerebral cortex and grey matter development and increases SA of brain

Where is the cisterna magna located and what does it contain

- b/w the cerebellum and occipital bone | - contains CSF

When would the cisterna magna be absent What measurement is considered abnormal

If the fetus has spinal bifida >10mm (marker for Down syndrome)

What are the linear folds sometimes seen in the cisterna magna

Dura fold that attach to the flax cerebelli

What is the falx cerebri

Double layer of dura mater that separates the cerebral hemispheres... considered to be a layer of the meninges

Where does the falx cerebri run?

W/in the longitudinal fissure/interhemispheric fissure

The thalamus is part of what larger structure of the brain? | What type of matter is it composed of?

Diencephalon Grey matter

What’s the function of the thalamus | Where is it located

- main relay center for sensory impulses... impulses from R side of the body are sent through the thalamus to the L cerebral hemisphere - posterior to the CSP

Where is the cerebellum located

-beneath the occipital lobes in the posterior fossa.... posterior to the pons and medulla

What separated the 2 lateral hemispheres of the cerebellum? How will the vermis appear on US

- cerebellar vermis and the falx cerebelli | - echogenic

What’s the function of the cerebellum

Coordinates movement

What is the tentorium

Dura matter that separates the occipital lobes of the cerebrum from the cerebellum

What happens to the circle of Willis in IUGR

-if there’s asymmetrical IUGR blood will be shunted to the brain and the middle cerebral artery will show high diastolic flow with decreased resistance

Which artery in the circle of Willis in most commonly dopplered

Middle cerebral artery