Peripheral NS Injury and Repair

Question 1

what are upper motor neurons?

Answer 1

Neurons in the cerebral cortex and
brainstem that govern the activity of
lower motor neurons in the brainstem and spinal cord

Question 2

what are gamma motor neurons?

Answer 2

LMNs that innervate
intrafusal muscle fibres
(muscle spindles)

Question 3

what are alpha motor neurons?

Answer 3

LMNs that innervate
extrafusal muscle fibres
for muscle contraction

Question 4

where do cranial nerve LMNs originate?

Answer 4

brainstem

Question 5

where are the cell bodies of somatic motor LMNs located?

Answer 5

anterior horn

Question 6

what is a motor unit?

Answer 6

The alpha motor neuron
and the skeletal muscle
fibres it innervates

Question 7

what sections of the spinal cord have englargements?

Answer 7

cervical and lumbosacral

Question 8

why do the cervical and lumbosacral parts of the spinal cord have enlargements?

Answer 8

to accommodate extra motor
units

Question 9

what are spinal nerves made up of?

Answer 9

posterior (dorsal) and anterior (ventral) roots

Question 10

what do spinal nerve split to become?

Answer 10

anterior and posterior rami

Question 11

what are the terminal branches of the brachial plexus?

Answer 11

peripheral nerves

Question 12

anterior hand posterior root combine to make what?

Answer 12

mixed spinal nerve

Question 13

how many cervical spinal nerves are there?

Answer 13

8

Question 14

how many thoracic spinal nerves are there?

Answer 14

12

Question 15

how many lumbar and sacral spinal nerves are there?

Answer 15

5

Question 16

how many spinal nerves are for the coccyx?

Answer 16

1-2

Question 17

what is a dermatome?

Answer 17

an area of skin that is mainly supplied
by afferent nerve fibres from
the dorsal root of a spinal nerve

Question 18

are peripheral nerve motor or sensory?

Answer 18

mixed!

Question 19

are cranial nerves also peripheral nerves?

Answer 19

yes

Question 20

what is upper motor neuron syndrome?

Answer 20

Damage to the descending tract before the anterior horn of the spinal cord

Question 21

what is lower motor neurone syndrome?

Answer 21

Damage to alpha motor neuron at or distal to the anterior horn

Question 22

is a stroke an upper or lower motor neurone injury?

Answer 22

upper

Question 23

what are signs of a stroke as an UMN injury?

Answer 23

usually they have some paresis
+ babinski/Hoffmans
hyperreflexia
hypertonia

Question 24

what is primarily affected in a spinal cord injury?

Answer 24

primarily UMN

Question 25

if you have a c spine SCI, it is likely what presentation?

Answer 25

UMN

Question 26

if you have a l spine SCI, it is likely what presentation?

Answer 26

LMN

Question 27

is weakness after a SCI unilateral or bilateral?

Answer 27

often bilateral

Question 28

where is weakness after a SCI?

Answer 28

below level of lesion

Question 29

people who've had a SCI have Hyper or hypo reflexia and tonia?

Answer 29

hyper

Question 30

what neurons are affected by ALS?

Answer 30

both UMN and LMN

Question 31

what is the ethology for ALS?

Answer 31

unknown

Question 32

what happens to the number of motor units when you have ALS?

Answer 32

it decreases

Question 33

is sensation involved in an alpha motor neuron injury?

Answer 33

no sensory involvement

Question 34

what happens when you have peripheral severe injury?

Answer 34

weakness and sensory loss

Question 35

what does Guillan barre syndrome cause?

Answer 35

Destruction of myelin sheath with axonal damage Rapidly progressing motor and sensory impairments

Question 36

what is the least severe axon injury?

Answer 36

neuropraxia (axon intact)

Question 37

what is the most severe axon injury?

Answer 37

neurotmesis (complete nerve lacaeration)

Question 38

what is axonotmesis?

Answer 38

Injury to axon and myelin but supporting connective tissue intact

Question 39

when does Wallerian degeneration occur?

Answer 39

when a nerve fiber is cut or crushed (axonotmesis or neurotmesis) and part of the distal axon degenerates

Question 40

what is amplitude?

Answer 40

of axons being stimulated

Question 41

what is latency most affected by?

Answer 41

demyelination

Question 42

what is latency?

Answer 42

time between stimulation and M wave

Question 43

what is conduction velocity affected by?

Answer 43

axonal loss and demyelination

Question 44

what does axonal loss result in?

Answer 44

lower amplitude

Question 45

what does demyelination result in?

Answer 45

prolonged latency m wave is spread because only some neurons affected slow conductor velocity

Question 46

what is motor unit potential?

Answer 46

Summation of electrical activity of the muscle fibres of the motor unit

Question 47

what can needle MEG be used to distinguish?

Answer 47

between LMN, UMN, and myopathies

Question 48

what are the 2 types of peripheral nerve recovery?

Answer 48

axonal repair and regrowth collateral sprouting

Question 49

where is axon regeneration faster?

Answer 49

closer to the injury site and slower further away

Question 50

what are the 2 key players in axonal regrowth?

Answer 50

macrophages and Schwann cells

Question 51

what is the purpose of macrophages?

Answer 51

they clear away the degenerating parts

Question 52

what is the purpose of the Schwann cells?

Answer 52

they act as a guide and simulate regrowth

Question 53

how do Schwann cells support axon regrowth?

Answer 53

a growth cone extends to search for target provides a framework to guide growing axons secretes neurotrophic signals to promote axon growth

Question 54

does a crush injury (axonotmesis always result in wallerian degernation?

Answer 54

no

Question 55

is axon recovery more rapid and complete in crush or cut nerve injuries?

Answer 55

crush

Question 56

is a nerve is cut, it can be surgically reattached within what time frame?

Answer 56

within 3 months

Question 57

what causes outcomes to be poor with axonal regrowth?

Answer 57

if the injury is severe and distal end is not available for reapposition

Question 58

what nerve did Henry hEEAD TRANSECT ON HIMSELF?

Answer 58

Radial nerve

Question 59

what can healthy aging and diseases cause?

Answer 59

it can decrease the number of motor units

Question 60

what is collateral sprouting?

Answer 60

motor unit size increases