11-24 NeuroEMBRYOLOGY Flashcards

1
Q

A: What is Neurulation?

B: List the 5 Steps of Neurulation

C:
β€’What does the Rostral part of the neural tube become?
β€’What does the CAUDAL part of the neural tube become?
β€’What does the Lumen of the neural tube become? [2]

A

Neurulation
A: Formation & closure of the neural tube

B:
1st. Notochord induces overlying ectoderm to differentiate into NEUROectoderm–>form neural plate.

2nd. Notochord stays behind to form adult [nucleus pulposus] of intervertebral disk
3rd. Neural Plate folds to create neural tube –open at both ends = ANT and POST neuropores. (These neuropores connect neural tube lumen with amniotic cavity)
4th. {NEUROPORE CLOSE UP} ANT neuropore closes on day 25 and becomes [lamina terminalis]. ////POSTERIOR neuropore closes on day 27

Rostral part—–>Adult Brain :-)

CAUDAL partβ€”->ADULT SPINAL CORD

Neural tube Lumenβ€”->ventricular system of brain AND central canal of Spinal Cord

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2
Q

1) What happens if the ANT neuropore FAILS to close on day __ of Neurulation ?
2) What happens if the POSTERIOR neuropore FAILS to close on day ___ of Neurulation?

A

1) When ANT neuropore FAILS to close Day 25 = upper neural tube defectsβ€”>Anencephaly
- ————————————————————————————–

  1. When POSTERIOR neuropore FAILS to close Day 27 = Lower neural tube defectsβ€”>[spina bifida with myeloschisis]
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3
Q

Neural crest cells differentiate from ______ of the ____ ____ and undergo prolific migration to ultimately form _______. This happens in Both the Cranial Region AND Trunk Region.

B: Describe the Neural Crest Cells development in each Region
Cranial [4]
TRUNK [ 6]

A

Neural crest cells differentiate from NEUROectoderm of the Neural tube and undergo prolific migration to ultimately form ADULT CELLS.

Cranial Region= Pharyngeal Arch stuff / pia&arachnoid / [pterygopalatine, otic and multiple sensory ganglia]

vs.

TRUNK Region= melanocytes / Schwann cells / Chromaffin of Adrenal Medulla / DRG / SCGT / Abd&pelvic parasympathetic ganglia(messier & Auerbach; CN10)

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4
Q
  1. Neurocristopathy

2. What are 3 good examples of this?

A
  1. Any dz related to maldevelopment of [Neural Crest Cells]
    • Medullary Carcinoma of Thyroid
    • Schwannoma
    • Neurofibromatosis type 1 (von Recklinghausen dz)
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5
Q

[Medullary Carcinoma of Thyroid] is a type of ______
A: Describe this Dz

B: How are the Carcinoma cells typically arranged?

A

[Medullary Carcinoma of Thyroid] is a type of NEUROCRISTOPATHY

A: endocrine neoplasm of parafollicular cells which secrete calcitonin and are from neural crest origin

B: Cells are usually arranged in cell nest surrounded by stroma bands that contain amyloid

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6
Q

[Schwannoma] is a type of ______
A: Describe this Dz

B: Where is this tumor commonly located? [2]

C: List clinical findings of this dz [2]

A

[Schwannoma] is a type of NEUROCRISTOPATHY

A: benign tumor of Schwann cells of neural crest origin that is well-circumscribed & encapsulated

B:

1) On Cerebellopontine angle near Vestibular branch of CN8 = β€œacoustic neuroma”
2) On [Trigeminal/CN5] due to its close approximation to [petrous ridge]

C:

  • Tinnitus
  • Hearing Loss
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7
Q

[Neurofibromatosis type 1] (AKA ___ _____ dz) is a type of ______
A: Describe this Dz [4]

B: What is the mode of inheritance for this dz

C: List clinical findings for this dz [4]

A

[Neurofibromatosis type 1] (AKA von Recklinghausen dz) is a type of NEUROCRISTOPATHY

A: Mutation in the NF1 geneβ€”> INC in Neurofibromin
–>this inappropriately DOWN regulates p21 tumor suppressor —–> neurofibroma tumors!

B: AUTOSOMAL DOMINANT

C:
β€’neurofibroma tumors widely dispersed
β€’Proliferation of all elements of peripheral nerves
β€’[cafe au lait] pigmented skin lesions
β€’[Lisch nodule] pigmented iris hamartomas

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8
Q

A: Name & Describe the 3 PRIMARY Brain Vesicles and their 2 associated Flexures

B: When does this stuff develop?

A

A: PRIMARY Brain Vesicles:
1. PROSENCEPHALON (FOREBRAIN)–> TELENCEPHALON & DIENCEPHALONS

  1. Mesencephalon (Midbrain) = remains as Mesencephalon
  2. rhombencephalon (hindbrain)β€”> metencephalon & myelencephalon

Flexures:
ΒΊ[Cephalic midbrain flexure]= between Mesencephalon and metencephalon

PRIMARY VESICLE development = WEEK 4!

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9
Q

The 5 SECONDARY Brain vesicles form during Week __ and form ________. Describe what they form exactly?

  1. TELENCEPHALON [4]
  2. DIENCEPHALON [5]
  3. Mesencephalon [3]
  4. metencephalon [2]
  5. Myelencephalon
A

SECONDARY Brain vesicles = Week 6

  1. TELENCEPHALON = cerebral cortex/basal ganglia/hippocampus/amygdala
    β€œBACH”
  2. ## DIENCEPHALON = THALAMUS / hypoTHALAMUS / PINEAL GLAND / CHOROID PLEXUS / PITUITARY GLAND
  3. ## Mesencephalon = Tegmentum / Tectum / Peduncular Region
  4. metencephalon = pons / cerebellum
  5. Myelencephalon = Medulla
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10
Q

The Spinal Cord develops from the ____ _____

What is the [ALAR Sensory Plate] ? [2]

A

Spinal Cord develops from the POSTERIOR NEUROPORE

[ALAR Sensory Plate]
β€’Dorsolateral thickening of intermediate zone of neural tube
β€’Gives rise to sensory neuroblast of Dorsal Horn –> eventually BECOMES spinal cord Dorsal Horn

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11
Q

The Spinal Cord develops from the _____ ______

What is the [BASAL Motor Plate]? [2]

A

Spinal Cord develops from the POSTERIOR NEUROPORE

[BASAL Motor Plate]
β€’Ventralateral thickening of intermediate zone of neural tube
β€’Gives rise to Motor neuroblast of Ventral AND Lateral Horns –> eventually BECOMES spinal cord Ventral Horn

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12
Q

A: Sulcus Limitans [2]

B: Caudal Eminence

Arises from _______ streak, blends w/_______ _______
β€”> gives rise to _______ & _______ segments of spinal cord

A

A: Sulcus Limitans
1. groove in lateral wall of neural tube (during week 4) that separates [ALAR Sensory Plate] from [BASAL Motor Plate]

  1. ## Extends from Spinal Cord to rostral midbrainB: ((Caudal Eminence))
    Arises from primitive streak, blends w/neural tube β€”> gives rise to sacral & coccygeal segments of spinal cord
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13
Q
  1. Myelination of Spinal Cord beings during month ____ in the _______ roots
  2. Oligodendrocytes accomplish myelination in the ___ vs. Schwann cells whom accomplish myelination in the _____
  3. Myelination of corticospinal tracts is not completed until after ___ years old and Myelination of [association neocortex] extends until you’re ____!
A
  1. Spinal Cord Myelination STARTS in month 4 within [Ventral Motor Roots]
  2. Oligodendrocytes accomplish myelination in the CNS! vs. Schwann cells whom accomplish myelination in PNS
  3. Myelination of Corticospinal tracts is not completed until after 2 years old….

and Myelination of [association neocortex] extends until you’re 30 YEARS OLD!

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14
Q

A: Describe the 3 Positional changes of Spinal cord

B: What is Disparate growth and what 2 things does it lead to?

A

A:

1) At 8 weeks= spinal cord extends length of vertebral canal
2) At Birth = Conus Medullaris extends to L3
3) In ADULTS = CONUS MEDULLARIS terminates at L1-L2

B: Disparate growth = growth between vertebral column & Spinal Cord β€”>Cauda Equina formation {which contains Dorsal AND Ventral Roots} AND [filum terminale]

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15
Q

[T or F] the Filum Terminale is a Neural-Active extension of the Spinal Cord

A

FALSE!!!!!

Filum Terminale is NON-NEURAL!

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16
Q

Describe Cerebellum Development

A

Brainstem:
Fundamental floor plan in spinal cord extends rostrally into developing brain stem keeping spatial relationship of alar and basal plates intact.
————————————————————————————–
————————————————————————————–
Cerebellum:
Develops from rhombic lip (meTencephalic thickening @ rostral bordr of 4th ventricle). Histogenesis continues until after birth.

17
Q

A: Development of the CEREBRAL CORTEX occurs ______ and is dominated by the growth of the ________.

B: Describe the pattern of development and migration of cells

C: Why does White and gray mater lie at different levels in the Cortex vs. Spinal Cord?

A

A: Development of CEREBRAL CORTEX occurs 4 MONTHS IN UTERO and is dominated by growth of the TELENCEPHALON

B: Cerebral Cortex demonstrates inside-out pattern in that later formed Neuroblast migrate peripherally beyond earlier-formed cells

C: After this migration, cell processes form and project Inward so that CORTEX WHITE MATER is DEEEEP to gray mater
but in Spinal cord…white mater is Superficial to gray mater

18
Q

The Hypophysis (AKA ___ ____) is attached to the ______ by the _____ ____ and consist of 2 lobes.

B: Describe these 2 Lobes

A

Hypophysis (AKA PITUITARY GLAND) is attached to HYPOTHALAMUS by the [Infundibula STALK] and consist of 2 lobes.

B:
1) [ANT Adenohypophysis], PARS Tuberalis & PARS Intermedia = develops from Rathke’s pouch-diverticulum of [stomodeum mouth cavity] and can become [craniopharyngioma]

2) [POST Neurohypophysis] = develops from [infundibulum stalk], neuroectodermal diverticulum of hypothalamus

19
Q

Spina Bifida occurs when ___ ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 4 Variations.

Describe [Spina Bifida Occulta] (3)

A

Spina Bifida occurs when BONY VERTEBRAL ARCHES fail to form properly!β€”> VERTEBRAL DEFECTS usually in LUMBOSACRAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 4 Variations }
————————————————————————————–
Spina Bifida Occulta
-multiple dimples on back of infant accompanied with tuft of hair
-leaast severe and occurs in 10% of population

-Spinal cord is intact and bony vertebral bodies are present along entire vertebral column BUT bony spinous processes terminate at higher level since vertebral arches didn’t form properly.

20
Q

Spina Bifida occurs when ___ ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 4 Variations.

Describe [Spina Bifida w. Meningocele] (2)

A

Spina Bifida occurs when BONY VERTEBRAL ARCHES fail to form properly!β€”> VERTEBRAL DEFECTS usually in LUMBOSACRAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 4 Variations }
————————————————————————————–
Spina Bifida w. Meningocele
ΒΊOccurs when meninges protrude thru vertebral defect and form sac filled with CSF!

ΒΊSpinal cord remains in normal position

21
Q

Spina Bifida occurs when ___ ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 4 Variations.

Describe [Spina Bifida w. Meningomyelocele]

A

Spina Bifida occurs when BONY VERTEBRAL ARCHES fail to form properly!β€”> VERTEBRAL DEFECTS usually in LUMBOSACRAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 4 Variations }
————————————————————————————–
** Spina Bifida w. Meningomyelocele **

Occurs when meninges AND SPINAL CORD protrude thru vertebral defect and form sac filled with CSF

22
Q

Spina Bifida occurs when ___ ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 4 Variations.

Describe [Spina Bifida w. Rachischisis]
A: What causes this and When does this occur. What does it lead to?

B: How are NTDs like this detected?

C: How are they prevented?

D: Is this considered a Lower NTDs or Upper NTDs and why?

A

Spina Bifida occurs when BONY VERTEBRAL ARCHES fail to form properly!β€”> VERTEBRAL DEFECTS usually in LUMBOSACRAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 4 Variations }
————————————————————————————–
** Spina Bifida w. Rachischisis **
A: MOST SEVERE SB Caused by POST neuropore of neural tube failing to close during WEEK 4β€”-> paralysis from level of the defect caudally

B: Can be diagnosed parentally by detecting elevated levels of [a-fetoprotein] in amniotic fluid

C: Prevented by pregnant women taking Folic Acid (0.4 mg/day)

D: THIS IS A LOWER NTDs! because it results from failure of POSTERIOR neuropore to close during week 4.

23
Q

Cranial Bifida occurs when ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 3 Variations.

Describe [Cranial Bifida w. meningocele ]

A

Cranial Bifida occurs when BONY SKULL fail to form properly!β€”> SKULL DEFECTS usually in OCCIPITAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 3 Variations }
β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”-
** Cranial Bifida w. meningocele **
Occurs when meninges protrude thru the skull defect and form sac filled with CSF

24
Q

Cranial Bifida occurs when ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 3 Variations.

Describe [Cranial Bifida w. meningoencephalocele ] (3)

A

Cranial Bifida occurs when BONY SKULL fail to form properly!β€”> SKULL DEFECTS usually in OCCIPITAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 3 Variations }
β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”
** Cranial Bifida w. meningoencephalocele **

  • Occurs when meninges AND BRAIN protrude thru skull defect and form sac filled with CSF
  • Noticed within infant’s 1st few days/weeks of life
  • OUTCOME IS POOR! :-( β€”> 75% die or severe retardation
25
Q

Cranial Bifida occurs when ____ ____ fail to form properlyβ€”>____ defect usually in the ______ region.
It is primarily caused by Pregnant Mothers not taking enough ____ ______. There are 3 Variations.

Describe [Cranial Bifida w. meningoHYDROencephalocele ]

A

Cranial Bifida occurs when BONY SKULL fail to form properly!β€”> SKULL DEFECTS usually in OCCIPITAL region. It’s primarily caused by Pregnant Mothers not taking enough FOLIC ACID.
{ 3 Variations }
β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”β€”
** Cranial Bifida w. meningoHYDROencephalocele**

Happens when meninges, BRAIN AND PART OF VENTRICLE protrude thru skull defect

26
Q

ANENCEPHALY/meroANENCEPHALY is a severe ____ NTD that occurs when _________β€”-> failure of ____ ____ ____ and ____ ___ to form.

B: Are infants with Anencephaly viable?

C: How is this Diagnosed?

D: How is this β€œtreated” ?

A

ANENCEPHALY/meroANENCEPHALY is a severe UPPER NTD that occurs when [ANTERIOR neuropore] fails to close—–>failure of [lamina terminalis] and [bony cranial vault] to form

B: NO! If not Stillborn, infants born with this survive for few hours-few weeks (Most common Dz in Stillborns)

C: Diagnosed via US

D: No tx BUT therapeutic abortion is usually performed

27
Q

A: What causes [Arnold-Chiari Malformation] ?

B: what are some Key Clinical signs [4]

C: This Malformation is commonly associated with what 4 other Dz?

A

A: Occurs when [caudal vermis], [cerebellar tonsils] and [medulla oblongata] herniate thru foramen Magnum

B:

  1. Syrinx in Cervical Spinal Cord
  2. Stretching of CN9, CN10, CN11
  3. Vocal Cord Paralysis
  4. Laryngeal stridor

C: Also associated with
ΒΊ[lumbar meningomyelocele]

ΒΊplatybasia (bone malformation at skull base)

ΒΊoccipitovertebral joint malformation

ΒΊ obstructive hydrocephalus (blocked magendie & Luschka)

28
Q

A: Dandy-Walker Syndrome

B: Clinical Signs

A

A: DWS= noncommunicating/nonobstructive hydrocephalus associated with atresia of [Foramen Magendie] and [Foramen Luschka]

B:

1) Dilation of 4th ventricle
2) Agenesis of cerebellar vermis and small cerebellar hemispheres
3) Occipital meningocele
4) Agenesis of Corpus Callosum Splenium

29
Q

A: Filum Terminale Syndrome

B: This Syndrome is associated with ___ tumors or ______

C: How do MD improve condition?

A

Filum Terminale Syndrome
occurs when TETHERED, Thick and Short filum terminale formsβ€”>weakness & sensory deficits in LE and neurologic bladder

B: Usually associated with LIPOMATOUS tumors or MENINGOMYELOCELES

C: Better after transection

30
Q

Craniostenosis

A

Premature closing of Cranial Sutures

31
Q

___ __ is the most frequent chromosomal abnormality and leading cause of ____ ______

B: What 5 Characteristic physical features of this dz

A

TRISOMY 21 is most frequent Chromosomal Abnormality and leading cause of MENTAL RETARDATION

B:

1) Flat facial profile
2) Slanting palpebral fissures
3) Epicanthic folds
4) open mouth
5) short stature and round head

32
Q

Lissencephaly agyria

A

Forebrain Malformation in which # of gyri DEC or are just ABSENT!! β€”>results in Smooth-surfaced brain = SEVERE neurological impairment rarely viable

33
Q

A: Microcephaly

B: Clinical signs [3]

C: Causes [3]

A

Forebrain Malformation in which Cortical neurons DEC
β€”>simplification of Cortical Gyri

B:

  1. STRIKING REDUCTION in head size
  2. Brain weighs less than 300 g (normal is ~1300 g)
  3. Seizures & Motor dysfunction

C:

  • HIV-1
  • Chromosomal abnormalities
  • Fetal Alcohol Syndrome
34
Q

Holoprosencephaly

A

incomplete separation of 2 cerebral hemispheres causing SINGLE TELENCEPHALIC MASS! Associated with Trisomy 13, midline facial problems and cyclopia

35
Q

Agenesis of [Corpus Callosum] may include absence of _____ and ______ commissures. It is often accompanied with ______ ____ ____. Pt may appear normal but often have ____ and _______

A

Agenesis of [Corpus Callosum] may include absence of ANTERIOR and HIPPOCAMPAL commissures. It’s often accompanied with MISSHAPEN LATERAL VENTRICLES. Pt may appear normal but often have FOCAL SEIZURES and MENTAL RETARDATION

36
Q

What VENTRICLES/PASSAGE does each of the Primary Brain Vesicles form? They do this in Week ___

A: Prosencephalon Forebrain = ______ + ______

B: Mesencephalon midbrain = ______

C: Rhombencephalon Hindbrain = ______

A

Primary Brain Vesicles = Week 4!
A: Prosencephalon Forebrain = [Interventricular Foramen of Monroe] + 3rd Vt

B: Mesencephalon midbrain = [Cerebral Aqueduct of Sylvius]

C: Rhombencephalon Hindbrain = 4th Vt