Lecture 16: Peripheral Nervous System Flashcards

1
Q

Where (in terms of somites) does the divison between Brain and Spinal Cord occur?

A

Brain is 4th Somite and Superior

Spinal Cord is Inferior to the 4th Somite

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2
Q

What is grey matter mostly made of?

A

Unmyelinated cell bodies

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3
Q

What is White Matter mostly made of?

A

Myelinated Axons

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4
Q

What region of the spine contains the Lateral Horns?

A

T1 to L2

(absent in most of the spine)

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5
Q

What is the dorsal part of the Spinal Cord (grey and white matter) primarily responsible for?

A

Sensory input

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6
Q

Before the Epiblast invaginates, is the region of the Alar Plate medial or lateral to the region of the Basal Plate of the future Neural Tube?

A

Lateral -The Alar Plate will be on top of the Basal Plate in the Neural Tube

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7
Q

What is found in the Alar Plate of the Neural Tube?

A

Sensory Neurons that never leave the Central Nervous System

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8
Q

Where do the Sensory Neurons of the Peripheral Nervous System (First Order Neurons) come from?

A

The Neural Crest

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9
Q

What comes from the Basal Plate of the Neural Tube?

A

Motor Neurons

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10
Q

What separates the afferent from the efferent nerves in the Neural Tube?

A

The Sulcus Limitans

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11
Q

What is the name for the center space in the Neural Tube?

A

Central Canal

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12
Q

What does the Intermediate Zone of the early Spinal Cord become?

A

Gray Matter

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13
Q

What does the Marginal Zone of the early Spinal Cord become?

A

White Matter

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14
Q

What cell type does the Ventricular Zone contain?

What do these cells do within the Ventricular Zone?

A

Stem Cells

They become Ependymoblasts, which can then either become Ependymal Cells or Choroid Plexus Cells (which make CSF)

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15
Q

What do Ventricular Zone Stem Cells become in the Intermediate Zone of the Early Spinal Cord?

A

Neruons, Astrocytes (protoplasmic), Glial Cells

(and others)

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16
Q

What do Ventricular Zone Stem Cells become in the Marginal Zone of the Early Spinal Cord?

What precursor to these cells is found in the Intermediate Zone?

A

Oligodendrocytes, Astrocytes (fibrous)

Glioblasts

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17
Q

What do Schwann Cells do?

What embryological structure do they come from?

A

They myelinate neurons of the Peripheral Nervous System

Neural Crest

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18
Q

What do Oligodendrocytes do?

What embryological structure do they come from?

A

They myelinate neurons of the Central Nervous System

Neuroectoderm

19
Q

What germ layer do Microglial Cells come from?

What do they do?

A

Mesoderm

They come from monocytes, which come from mesoderm

They are phagocytes

20
Q

In an early fetus, the Vertebrae and the Spinal Cord are the same length. What causes the Spinal Cord to stop short of the Vertebrae in a newborn?

A

The Vertebrae grow faster than the Spinal Cord

21
Q

Where does Keim say a newborn’s Spinal Cord stops?

Where does Keim say an adult’s Spinal Cord stops?

Why is this clinically relevant?

A

Newborn: L2-L3

Adult: L1-L2

NICU Spinal Taps are lower.

22
Q

What embryonic structure gives rise to the Spinal Ganglion Cells

A

Neural Crest

23
Q

What signal triggers early Dorsal Nerve differentiation?

What gives off this signal?

What kinds of nerves are these incited to become?

A

BMP

Roof Plate and Dorsal Surface Ectoderm

Sensory Nerves

24
Q

What signal triggers early Ventral Nerve differentiation?

What releases this signal?

What kinds of nerves are these incited to become?

A

Sonic Hedgehog

Floor Plate and Notocordal Process of the Notocord

Motor Neurons

25
Q

What signal triggers differentiation of the Spinal Cord into the Alar Plate?

A

BMP

26
Q

What signal triggers Spinal Cord differentiation into the Basal Plate?

A

Sonic Hedgehog

27
Q

What genes do high levels of BMP activate?

A

PAX3 and PAX7

BatMan’s Pouch might be on display at PAX

28
Q

What genes do high levels of SHH (Sonic Hedgehog) activate?

A

NKX2.2 and NKX6.1

“Sonic Hedgehog NKX2.2” and 6.1 sound like Sega skiing games to me

29
Q

In the Peripheral Nervous System, what two structures come from the Neural Tube?

A

Pre-ganglionic Autonomic Neurons (come from the lateral horn - remember this is only present from T1 to L2)

Motor Neurons

30
Q

Where do the Neurons of the Dorsal Root Ganglia come from?

What kind of Nerves (in terms of orientation) are they?

A

Neural Crest

Pseudo-Unipolar

31
Q

Where do the Sympathetic and Parasympathetic Ganglia come from?

A

Neural Crest Cells

32
Q

What embryological structures give rise to the nerves of the Ventral and Dorsal Rami?

A

The Rami are where the Dorsal Roots and Ventral Roots have already come together, so they are both Neural Crest and Neuroectoderm

33
Q

What does the Ramus Communicantes allow you to do?

A

“Get into and out of the Autonomic Ganglia”

34
Q

Where are the cell bodies for the Preganglionic Sympathetic Nervous System located?

What are they derived from?

A

In the Spinal Cord (lateral horn) in the Thoraco Lumbar Region

(T1-L2)

Neuroectoderm

35
Q

Where are the cell bodies for the Postganglionic Sympathetic Nerves?

What do they come from?

A

Off of the Spinal Cord, at the Synapse of the Preganglionic Nerves

Neural Crest Cells

36
Q

Which fiber of the Sympathetic Nervous system is Short vs Long?

Which Fibers are Myelinated?

A

Short / Myelinated: Preganglionic

Long / Unmyelinated: Postganglionic

37
Q

In what two regions of the spinal cord do we see Parasympathetic Nerves?

A

Cranial and Sacral

38
Q

In the Cranial Region, where do the Parasympathetic Nerves travel?

A

With Cranial Nerves 3, 7, 9, 10

39
Q

In the Sacral Region, where do the Parasympathetic Nerves travel?

A

With the 2nd, 3rd, and 4th Sacral Nerves

40
Q

For the Parasympathetic Nervous System

Preganglionic vs Postganglionic Fibers

Which ones are Long vs Short, and which ones are Myelinated vs Unmyelinated?

A

Preganglionic Fibers for the Parasympathetic Nervous System are long and myelinated.

Postganglionic Fibers are Short and Unmyelinated

41
Q

The cell bodies for which link of the Parasympathetic Nervous System are in the Parasympathetic Ganglia, and what are they derived from?

A

The Postganglionic Nerve Fibers

Neural Crest

42
Q

When does Central Nervous System Myelination begin, and when does it end?

What cell does this?

What is that cell derived from?

A

Starts in the 6th month, continues to year 23 or so.

Oligodendrocytes

Neuroectoderm (stem cells of the Ventricular Zone)

43
Q

When does Peripheral Nervous System Myelination begin?

Which nerves (motor or sensory) are Myelinated first?

What cell does this, and where does it come from?

A

About the 4th Month

Motor

Schwann Cells / Neural Crest

44
Q

What might a patient notice happens about the time the Motor Neurons of the Peripheral Nervous System begin to Myelinate in a fetus?

A

It begins to move and kick