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RHSC 420 > Day 2 - Peripheral NS and SC > Flashcards

Day 2 - Peripheral NS and SC Flashcards

1
Q

How many spinal nerves do we have?

A

31

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2
Q

What are the 2 general types of somatosensory receptors in the PNS?

A

Touch and Proprioception

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3
Q

What are the types of prioprioceptive somatosensory receptors?

A

1) Joint receptors

2) Muscle receptors

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4
Q

What do joint receptors do?

A

Sense joint position

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5
Q

What are the 3 types of muscle receptors?

A

1) Free nerve endings (chemoreceptors for muscle pain)
2) Muscle spindles (stretch receptors)
3) Golgi tendon organs

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6
Q

How are golgi tendon organs stimulated?

A

They fire during isometric muscle contractions - they sense the load and tell the muscle to let go if the load is too high

Sensing muscle strength

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7
Q

What is the function of muscle spindles?

A

They are stretch receptors attached to intrafusal muscle fibers (not the main bulk of the muscle) - they control muscle length and tone

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8
Q

What are the 2 main types of cutaenous receptors (touch receptors)

A

1) Mechano

2) Noci

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9
Q

What type of receptors are nociceptors?

A

Can be thermo or chemo

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10
Q

Where are golgi tendon organs located?

A

At the junction between the muscle and the tendon

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11
Q

How many cranial nerves in the human body?

A

12

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12
Q

What is an example of a cutaneous receptor for light touch?

A

Hair follicle receptor

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13
Q

What does a merkel receptor sense?

A

pressure and decreased frequency of vibration

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14
Q

What does a meissner corpuscle sense?

A

light touch

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15
Q

What does a Pacinian corpuscle sense?

A

vibration (“deep touch”)

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16
Q

What doe Ruffini endings sense?

A

skin stretch and pressure (“deep touch”)

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17
Q

What do nociceptors sense?

A

Pain - free nerve endings for pain and temperature

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18
Q

What type of receptors provide information in the PCML?

A

All cutaneous receptors except nociceptors (these provide info in the spinothalamic tract)

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19
Q

What receptors lead into the spinothalamic pathway?

A

Nociceptors

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20
Q

What is a nerve plexus?

A

fiber bundles branch to join other nerve fibers - this allows connection between peripheral nerves. E.g. if the long thoracic nerve is damaged, it is connected to C5, 6, and 7 nerves

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21
Q

What type (structural) of neuron is a somatosensory neuron?

A

unipolar

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22
Q

Where is the cell body of a peripheral somatosensory neuron located?

A

In the dorsal root ganglia, just outside of the SC

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23
Q

Where is the cell body of a peripheral motor neuron located?

A

ventral root of SC

24
Q

Describe the structure of a peripheral nerve (from inside out), starting at the axons

A

1) Many axons surrounded by endoneurium (endoneurium fills the space between axons), multiple bundles of axons in peripheral nerve
2) All the bundles are surrounded by perineurium
3) This makes a number of bigger bundles (fascicles), which are surrounded by epineurium

25
Q

What is each bundle of bundles of axons called?

A

A fascicle

26
Q

Are peripheral nerves just sensory, or just motor?

A

No - they carry both sensory and motor fascicles within on peripheral nerve

27
Q

What has faster conduction - an A fiber or a C fiber?

What about Ia vs. IV?

A

A - myelinated, has faster conduction
C - unmyelinated, slower conduction

Ia and IV are sensory fibers - Ia has myelination and thus will be faster

28
Q

What different things can we sense with our msk system (with muscle receptors?)

A

Joint position
Muscle strength
Muscle length

29
Q

What different things can we sense with our skin? (somatosensory receptors)

A 
Light touch
Pressure
VIbration
Deep touch = pressure + vibration
Pain
Temperature
Crude touch
30
Q

What tract controls conscious proprioception?

A

PCML

31
Q

What tract controls unconscious proprioception?

A

Spinocerebellar

32
Q

Describe the general locations of the dermatomes

A 
C2-C3 back of head
C4 neck
C5-6 lateral arm, thumb
C7-8 back of arm, fingers
T1 - medial arm
T2-12 torso
T4 nipples
T10 umbilicus
L1-5 front of legs
S1-2 buttocks, back of legs
S3-4 genitals
S4-5 peri-anal region
33
Q

Does each myotome have just one spinal nerve causing the movment?

A

No - but the nerves listed in the myotomes are the largest contributors to the movement. You have to test several myotomes to hone in on damage

34
Q

List the myotomes

A 
C1-4 neck muscles
C3-5 diaphragm
C5 elbow flexors
C6 wrist extensors
C7 finger extensors
C8 wrist flexors, finger flexors
T1 - finger abductors
T1-L5 trunk muscles, intercostals, abdonminal wall muscles
L2  hip flexors
L3 knee extensors
L4 ankle dorsiflexors
L5 toe extensors
S1 ankle plantar flexors
S2-S4 pelvic diaphragm, genital muscles
35
Q

Describe the steps in the cascade associated with skeletal muscle innervation

A

1) Action potential comes in
2) Voltage gated calcium channels open
3) Calcium influx causes vesicles to fuse with membrane
4) Ach is released into synaptic cleft and binds to receptors causing ion channels to open
5) Influx of sodium which depolarized postsynaptic cell
6) Depolarization causes calcium release which initiates muscle contraction

36
Q

What is damage to a single nerve called?

A

Mononeuropathy

37
Q

What is damage to more than one nerve called?

A

Polyneuropathy

38
Q

What is damage to a spinal nerve called?

A

Radiculopathy

39
Q

What is plexopathy?

A

Damage to one of the plexuses

40
Q

What is dysesthesia?

A

Abnormal sensation whether provoked by stim. or not

41
Q

What is Paresthesia?

A

unusal feelings, e.g. pins and needles, without any stim.

42
Q

What is it called when previously non-painful stimuli become painful?

A

Allodynia

43
Q

What is Hyperalgesia?

A

Normally painful stim. is even more painful

44
Q

What is Hyperesthesia?

A

Increased sensory perception

45
Q

What is a decrease in sensory perception called?

A

Hypoesthesia

46
Q

How does a peripheral nerve injury usually occur?

A

Mechanical damage or compression

47
Q

What is a mild nerve compression called? What is the prognosis for healing?

A

Neuropraxia - easier to heal because axon and myelin intact

48
Q

What is it called when the axon is damaged but the myelin stays intact? What is the prognosis for healing?

A

Axonotmesis

Everything beyond the damaged axon dies, but the myeline provides a path for regrowth

49
Q

What is neurotmesis? What is the prognosis for healing?

A

Both axon and myelin are damaged

Results in formation of neuroma (benign growth of nerve tissue), axon can’t find it’s way back along original course

50
Q

What are the two divisions of peripheral neuropathies?

A

Demyelinating

Axonal

51
Q

What are some clinical clues to possible demyelination peripheral neuropathy?

A
  • Diffuse weakness
  • Early loss of reflexes (b/c reflexes are highly myelinated)
  • Non-length dependent distribution
  • Rapid ascending symptoms
  • Preceding infection
  • Decreased conduction velocity
52
Q

What are some clinical clues to axonal peripheral neuropathy?

A
  • More distal weakness
  • Reflexes are less affected
  • Length-dependent distribution (e.g. glove and stocking in diabetes)
  • Usually chronic progression, though some acute/subacute
  • Conduction amplitude is decreased
53
Q

What is Guillain-Barre Syndrome (GBS)?

A

An acute polyneuropathy, usually following an infection such as influenza. It is a demyelinating condition.

54
Q

What are some of the sensory and motor sx. of GBS?

A

Sensory:

  • Numbness/tingling in the feet that ascends to the legs and into arms
  • Large fiber > small fiber impairment
  • Can have face/trunk involvement
  • Occassionally neuropathic pain in back and limbs

Motor:

  • Distal>proximal weakness
  • Can progress to tetraplegia
  • Begins in legs, spreads up
  • Facial weakness in 50%
  • Ophthalmoplegia and/or ptosis in 5-15%
  • about 1/3 develop respiratory failure
  • may cause hypo/hypertension + cardia arrhythmia
55
Q

Describe symptoms of diabetic neuropathy

A

Glove and stocking numbness due to Axonal damage - length dependent distribution
Affects sensory more than motor because sensory neurons are generally longer

May have high stoppage gait due to loss of ankle dorsiflexion (if motor neurons are affected)

56
Q

What causes Myasthenia gravis?

A

Auto-immune damage at the post-synaptic membrane of the NMJ

- body attacks Ach receptors

RHSC 420 (13 decks)

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