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🟡 Neuroscience 🟡 > Peripheral Nerve Injury > Flashcards

Peripheral Nerve Injury Flashcards

1
Q

True or false
All of the spinal cord is a part of the CNS

A

False

The anterior horn cells of the spinal cord is PNS.

(Because they are a part of the motor unit)

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2
Q

True or false
Anterior horn cells are located in the gray matter of the spinal cord

A

True

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3
Q

True or false
The optic tract is a part of the PNS

A

False
CNS

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4
Q

True or false
The optic nerve is a part of the PNS.

A

True

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5
Q

Are cranial nerves PNS or CNS?

A

PNS

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6
Q

What PNS disease involves the anterior horn neurons/cells ?

A

Polio

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7
Q

The nuclei for cranial nerves in the brainstem are (PNS/CNS) ?

A

PNS

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8
Q

Understand the structure

A

Ok

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9
Q

What does the PNS consist of ?

A

Cranial and Spinal nerves
Efferent and Afferent axons
Myelinated and nonmyelinated
- epineurium
- perineurium
- endoneurium

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10
Q

Is efferent sensory or motor

A

Sensory

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11
Q

Is afferent sensory or motor

A

Motor

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12
Q

Is there such a thing as nonmyelinated axons?

A

No

All axons have myelin but the myelinated axons are WRAPPED in myelin sheath while nonmyelinated axon has myelin embedded into it.

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13
Q

What are the endoneurium, perineurium epineurium?

A

They are connected tissue inside nerves that function to support and protect nerves.

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14
Q

Difference between myelinated, and non-myelinated axons

A
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15
Q

Explain the Schwann cell function in PNS

A
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16
Q

Peripheral nerve injury is classified into three groups:

A

Neurapraxia
Axonotmesis
Neurotmesis

17
Q

Which one of the peripheral nerve injury classifications is the simplest one

A

Neurapraxia

18
Q

What is neurapraxia?

Give example

A

(Myelin and nerves are intact, no cuts or lesions just compression that may have impeded the blood supply)

Goes away pretty quick . Can take seconds, minutes, days, a week, depending on the pressure applied and duration.

Ex: waking up to a numb arm that you slept on

19
Q

What usually causes neurapraxia?

A

Compression or ischemia, resulting in ischemia of the myelin sheath.

20
Q

Can neuropraxia be reversed ?

A

Yes if the injurious agent is removed

21
Q

Describe the damage in neuropraxia and how recovery occurs

A

Nerves remain intact
Wallerian degenration does NOT occur

Recovers by re-myelination of distal segment

22
Q

Neuropraxia time of recovery

A

2-12 weeks

(Normal motor action potential expected distal to the site of injury by day 10)

23
Q

true or false
The sensory and motor loss is permanent in neuropraxia

A

False

Temporary

24
Q

What is Wallerian degeneration

A
25
Q

What is axonotmesis

A

(Nerve is not cut but there is an inner lesion)

26
Q

What causes axonotmesis

A

Severe compression or crush

27
Q

Describe the damage in axonotmesis

A

Wallerian degeneration occurs distally and proximally to the closest node of Ranvier

28
Q

Axonotmesis repair and recovery time

A

Repair is a combination of:
- collateral sprouting in lesser injuries
- axonal regenration in more severe injuries

(BUT this takes a longer time to repair as nerves have slow regeneration)

Time to recovery: 2 - 6 months
(Degree of recovery depends on: age, site of injury, and amount of fibrosis)

29
Q

What is neurotmesis

A

(Complete cut of a nerve / myelin and axon are cut)

30
Q

Describe the damage in neurotmesis

A
31
Q

Neurotmesis repair and recovery time

A

(Surgery puts nerve ends together, but cannot put together each and every axon back to the way it used to be, resulting in PLASTICITY)

(Can never return 100% back to normal)

32
Q

True or false
Plasticity is a complication of Neurotmesis surgical repair

A

True

33
Q

What are the four major plexuses?

A

cervical
Brachial
Lumbar
Sacral

34
Q

Causes of peripheral nerve injury (open and closed)

A
35
Q

What are the mechanisms of nerve injury?

A

Laceration injury
Crush injury
Avulsion injury
Thermal injury

36
Q

Laceration and injury 

A
37
Q

Crush injury

A

🟡 Neuroscience 🟡 (3 decks)

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