Development of the Nervous System Flashcards

1
Q

What is the nervous system developed from? What is the notochord formed from?

A

ECTODERM

  • notochord = MESODERM
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2
Q

Induction of the neural plate is done by what structure? Which week of development?

A

NOTOCHORD (mesodermal origin)

  • induces invagination of neural plate
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3
Q

What cells form the cranial nerve sensory cells and dorsal root ganglia cells? Where do they form?

A

NEURAL CREST CELLS

  • form post-ganglionic Autonomic cells (parasympathetic & sympathetic)
  • form at the top of the neural tube, will push away & migrate laterally
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4
Q

What 6 distinct neurons do the NEURAL CREST cells differentiate into?

A
  1. Cranial Nerve Sensory & Ganglion cells
  2. Dorsal Root Ganglion Cells
  3. Post-ganglionic Autonomic
  4. CHROMAFFIN cells of adrenal medulla
  5. SCHWANN CELLS
  6. Melanocytes

NOT VENTRAL ROOT**

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5
Q

What do the mesodermal cells alongside the neural tube begin to form?

A

SOMITES

  1. Skeletal muscle
  2. Vertebrae
  3. Dermis
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6
Q

What 3 distinct vesicles does the anterior aspect of the NEURAL TUBE develop into?

A
  1. Prosenchephalon (forebrain)
  2. Mesencephelon (midbrain)
  3. Rhombencephelon (hindbrain)
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7
Q

What 5 vesicles form from the 3 vesicles of the Neural Tube?

A
  1. Telencephelon
    (cerbral cortex, basal ganglia, hippo campus, amygdala)
  2. Diencephelon
    (thalamus, hypothalamus, choroid plexus, pineal body)
  3. Mesencephelon
    (tegmentum, tectal, peducular regions)
  4. Metencephelon
    (pons, cerebellum)
  5. Myelencephalon
    ( medulla/brainstem)
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8
Q

Which areas have the greatest growth?

A

Cerebral hemisphere (telencephelon)

&

Brainstem
(myelencephelon)

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9
Q

What are the 3 main flexures?

A
  1. Cephalic
  2. Pontine
  3. Cervical

(in order)

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10
Q

What are the 2 secondary vesicles of the forebrain/prosencephelon? What regions does each secondary vesicle cover? What ventricles?

A
  1. Telencephelon & Diencephelon
2) T= 
cerebral cortex & 
basal ganglia, 
amygdala
D = 
1 - thalamus
2- hypothalamus
3 - pituitary
4 - pineal gland

3) T= Lateral Ventricle( of Monroe)

D= 3rd Ventricle

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11
Q

What are the 3 layers of the Neural Tube? Which layer is 1st to form & fastest growing?

A
  1. Ventricular (inner layer)
  2. Mantle (intermediate layer) –> GRAY MATTER (cell bodies)
  3. Marginal Layer (outer)
    - White matter –> AXONS
    MMV

VENTRICULAR!!! first & fast proliferating

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12
Q

Which cells of the 3 layers become gray matter? Which become white matter?

A

GREY = MANTLE (2nd layer –> cell bodies)

White = MARGINAL (outer layer–> Axons)

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13
Q

What do Alar Plate neurons contribute to? Basal Plate?

Where are they found in regards to the Sulcus Limitans?

A

Alar = SENSORY pathways
- DORSAL to Sulcus

Basal Plate = MOTOR
- Ventral to the Sulcus Limitans

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14
Q

Which cells will invade the adjacent somites?

A

those more VENTRALLY within the mantle

Basal Plate = MOTOR–> to the ventral root of spinal chord

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15
Q

Which axons form the TRACTS??

A

Axons in the MARGINAL zone

white matter –> axons
- grow to brain or spinal chord

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16
Q

What are the fibers within the Dorsal Sensory Horn?
In the Ventral Motor Horn?

Following options:
GSA, GVA, GVE, GSE

A

Dorsal:

  1. GSA - sensory input (touch, pain, temp)
  2. GVA - sensory to smooth muscle(internal organs)
  3. GVE - parasympathetic

Ventral:
1. GSE - motor to skeletal muscle (alpha motor neurons**)

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17
Q

A 7 day old infant was evaluated because of intermittent vomiting that began a day after birth. A barium enema demonstrated contraction of the colon near the rectum and a length of colon proximal to the contraction was severely distended. Biopsy revealed an absence of autonomic ganglia cells in the colon. The most likely cause of this disorder was:

a. defective formation or migration of neural crest cells
b. failure of closure of the rostral neuropore
c. failure of closure of the caudal neuropore
d. lack of separation of the telencephalic vesicles
e. increased proliferation or migration of CNS neurocytes

A

A) Defective formation or migration of neural crest cells

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18
Q

What forms from the lateral ends of the BRAINSTEM? Because the roof plate expands, where is the ALAR plate relative to the basal plate?

A

FOURTH VENTRICLE

*****LATERAL to the basal plate

alar = sensory
Basal = Motor (a= 1st, B = 2nd)
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19
Q

Which foramen develop laterally in the Medulla(myelencephelon)? Medially? Which contains sensory components & which motor?

A

Laterally = Foramen of LUSCHKE (sensory)

Medially = FORAMEN OF MAGENDIE (motor)

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20
Q

What are the 2 principle components of the Metencephelon?

A
  1. PONS
  2. Cerebellum!!!

t. PC

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21
Q

What are the 2 basic divisions of the pons?

A
  1. Dorsal Tegmentum
  2. Ventral Region
Dorsal = Tegmentum
Ventral = BASILAR PONS
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22
Q

What is derived from the DORSAL aspect of the Alar Plate? Central Part?Lateral?

A

CEREBELLUM***

central = VERMIS

lateral = Cerebellar Hemispheres

23
Q

What is the function of the cerebellar cortex?

A

integrating information –> motor memory or muscle memory

24
Q

Why is cell migration in the cerebellum different from brainstem & spinal chord?

A
  • cells near surface migrate INWARD to form granule cell layer
  • push cells from proximal to distal layers
25
Q

What are the 3 regions of the Midbrain? Which section of the brain is it?

A

MESENCEPHALON

  1. Tectal Region - dorsal –> Sensory info (colliculi)
  2. Tegmentum - middle
  3. Peduncular - ventral
26
Q

What important structure is formed in the cavity of the midbrain vesicle?

A

Aqueduct of Sylvius OR

Cerebral Aqueduct

  • CSF from forebrain ventricle to the fourth ventricle
27
Q

What types of fibers are found in the Midbrain?

A
  1. GSE - (oculomotor)
  2. GVE (edinger westphal nuc.)
  3. GSE (Trochlear Nuc.)
  4. GSA ( mesencephalic nuc. of 5)

1,2,3, 4

28
Q

What types of fibers are in the PONS?

A

5 , 6 , 7,

  1. GSE (CN 6)
  2. GVE (sup. Salivatory Nuc.) (CN 6)
  3. SVE (CN 9 - motor facial nuc.)
  4. GSA (CN 5 - principle sensory nuc.)
  5. GSA (CN. 5)
29
Q

What types of fibers are in the medulla oblongata?

A

1, GSE - CN 12

  1. GVE - CN 10
  2. SVE
  3. SVA
  4. GVA
  5. SSA
  6. GSA -

8,9,10,12

30
Q

What types of fibers are in the spinal chord?

A

GSE
GVE
GVA
GSA

31
Q

From what are the optic vesicles formed? What will the rostral part form? The medial portion?

A

FOREBRAIN (diencephelon)

  • Rostral –> forms TELENCEPHALON
  • Medial –> DIENCEPHELON
32
Q

Where is growth most rapid in the diencephalon? Because it is so rapid, what is the “bridge” that forms between?

A

THALAMUS

  • MASSA INTERMEDIA!

(3rd ventricle will form here)

33
Q

From what does the hypothalamus form? What does it control?

A

3rd ventricle –> ventral region slower –> forms HYPOTHALAMUS

  • control sleep, digestion, body temp, emotion (via limbic)
other ventral structures:
optic chiasm
maxillary bodies
tuber cinerum
infundibulum
34
Q

From what is the Cerebral cortex derived?

A

TELENCEPHELON

  • most rostral-
  • 2 outpocketings (Cerebral Hempisheres)
  • median–> LAMINA TERMINALIS
35
Q

How do the lateral ventricles communicate with the lumen of the diencephalon?

A

Via interventricular FORAMEN OF MONRO

36
Q

What is formed from the continued growth of the cerebral hemispheres?

A

CEREBELAR CORTEX

37
Q

What is formed once the roof plate of the Cerebral Hemispheres fuse with the pia mater containing the vascular mesodermal tissue?

A

CHOROID PLEXUS of the LATERAL VENTRICLE

38
Q

What forms the medial surface of the telencephalic vesicle?

A

Hippocampal formation (archipallium)

39
Q

What connects the hippocampus with the hypothalamus?

A

FORNIX

40
Q

What are the 3 commissures of the TELENCEPHALON and what do they connect?

A
  1. Corpus Callosum - Left & right hemispheres
  2. Anterior COmmisure - limbic system & temporal lobe
  3. Posterior Commissure - visual & integrative components
41
Q

What is the disorder when the posterior neuropore fails to close?

A

Spina Bifida

42
Q

What are the 3 types of spina bifida and their symptoms?

A
  1. Spina Bifida Oculta
    - no neural tissue, defect is covered by skin/patch of hair
  2. Spina Bifida Cystica
  • neural tissue protrudes through arch –> cyst sac
    A) meningocele - only fluid
    B) Meningomyelocele - neural tissue in sac
  1. Rachischisis
    - neural tissue become necrotic, or fails to form

*** fix w/ folic acid

43
Q
  1. What is it called when the meninges protrude through the defect in the ossification of the skull?
A

. If only the meninges protrude through the defect (hole),

= meningocele.

44
Q

If brain tissue protrudes through the defect in the skull it is called what?

A

If brain tissue protrudes it is a

meningoencephalocele!!

45
Q

If the ventricles are involved, it is called what?

A

if the ventricles are involved

= meningohydroencephalocele

46
Q

What is the last thing to form?

A

SKULL

  • nervous system before skull formation
47
Q

What is exencephaly? What happens if brain tissue becomes necrotic? What is it called if the defect continues into the spinal chord?

A

Cephalic Neural Tube does not close

  • skull does not form
  • MALFORMED brain exposed
  1. necrotic –> called ANENCEPHALY
  2. CRANIORACHISCHISIS
48
Q

What is the name for the defect when CSF accumulates in the ventricular system? How does this occur? Where does fluid build up?

A

HYDROCEPHALY

  • narrowing, stenosis of AQUEDUCT OF SYLVIUS
  • builds up in LATERAL VENTRICLES

–> skull expands since cranial sutures have not fused

49
Q

What is the term for the caudal displacement of the posterior canal fossa though the foramen magnum? What usually gets displaced?

A
  • herniation of CEREBELLUM

called:
Arnold - Chiari Malformation

50
Q

What is microcephaly?

A

Cranial vault that is smaller than normal

  • due to lack of Brain Development
  • small forehead
51
Q

A two day old female infant presents with a small pigmented area at the midline on her lower back. Close examination reveals a small tuft of delicate hairs associated with a small cutaneous dimple. Which of the following most closely signifies with this defect?

a. Rachischisis
b. Encephalocele
c. Spina bifida aperta
d. Spina bifida cystica (sac like defect exposed)
e. Spina bifida occulta

A

E. SPina Bifida Occulta

52
Q

A stillborn infant was noted to have a grossly abnormal skull and cerebrum. The parietal bones, most of the occipital bones, and most of the frontal bones above the orbits were absent. A malformed remnant of the cerebrum, with few recognizable structures, was exposed at the site of the skull defect. The most likely explanation for this malformation was:

a. defective formation or migration of neural crest cells
b. failure of closure of the rostral neuropore (anencephaly)
c. failure of closure of the caudal neuropore
d. blockage of the cerebral aqueduct
e. increased proliferation or migration of CNS neurocytes

A

b. failure of closure of the rostral neuroprore (anencephaly)

53
Q

A 7 year old boy is brought to the pediatrician by his mother, who complains that the boy has had progressive difficulty seeing/reading the assignments posted on the board by the teacher. Examination reveals a boy who is noticeably small for his age, has partial vision loss in both eyes peripherally, but otherwise appears healthy. MRI of the brain reveals a craniopharyngioma – Rathke’s pouch tumor – which is an aberrant outpocketing of the stomodeum. Which one of the following is most directly involved in the developmental defect seen in this boy?

a. Adenohypophysis
b. Neurohypophysis
c. Optic chiasm
d. Hypothalamus
e. Thalamus

A

A.) Adenohypophysis

54
Q

A child is born with a large mass on the forehead, a partially cleft nose, and ocular hypertelorism (widely spaced orbits). CT and MRI reveal a defect in the frontal bone and a mass containing fluid, portions of the frontal lobe, and a cavity that is continuous with the anterior horn of the right lateral ventricle. Which of the following best describes this type of mass?

a. Meningocele
b. Meningoencephalocele
c. Meningohydroencephalocele
d. Meningomyelocele
e. Microencephaly

A

c. Meningohydroencephalocele