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Y2 HNN > clinical neurophysiology > Flashcards

clinical neurophysiology Flashcards

1
Q

what body area is supplied by nerve roots C1-C8?

A

neck and arms

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2
Q

what body area is supplied by nerve roots T1-T12?

A

intercostals/chest

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3
Q

what body area is supplied by nerve roots L1-L5?

A

legs

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4
Q

what body area is supplied by nerve roots S1-5?

A

pelvic floor and organs

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5
Q

what is the function of the intervertebral disc?

A

cushioning for vertebrate and act as shock absorbers for the spine

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6
Q

what is an intervertebral disc prolapse and what type of pain does it cause?

A

intervertebral disc prolapse = when the nucleus pulposus bulges out due to trauma or congenital weakness and presses on spinal nerve roots –> radicular pain

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7
Q

what is sciatica and what nerve root is affected?

A

Sciatica is pain that radiates down the back of the leg on one side (along path of sciatic nerve but not related to it)
Caused by nerve root issue at L5

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8
Q

what is epidural space in SC, is it potential or true in the SC and what is found in it?

A

space between the dura and and vertebral periosteum
True space in SC
Filled with fat and venous plexuses

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9
Q

what is the denticulate ligament and where are lateral denticulate ligaments found?

A

extensions of Pia mater that anchor the spinal cord to the dura (run in subarachnoid space)

lateral denticulate ligaments separate the anterior and poster roots

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10
Q

Form the anterior and posterior roots, which is motor and which is sensory?

A 
Anterior/ventral = motor
Posterior/dorsal = sensory
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11
Q

if there was an arterial problem in the spinal cord what part would it usually affect?

A

affects anterior part of spinal cord

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12
Q

what part of the body does the fasciculus gracilis sense fine touch, vibrations and proprioception from?

A

from ipsilateral lower limb

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13
Q

what part of the body does the fasciculus cuneatus sense fine touch, vibrations and proprioception from?

A

ipsilateral upper limb

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14
Q

what does the spinocerebellar tract detect?

A

proprioception from limbs to cerebellum

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15
Q

what does the Spinothalamic tract detect?

A

pain and temperature from the contralateral side of the body

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16
Q

how do the anterior and lateral corticospinal tracts differ ?

A

Anterior (15%)= motor to ipsi- and contralateral anterior horn
Lateral (85%)= motor to ipsilateral horn

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17
Q

where are motor and sensory cell bodies found?

A

Motor cell body found in ventral/anterior horn

Sensory cell body found in dorsal root ganglion

18
Q

what is one muscle fibre supplied by?

A

one motor neuron

19
Q

what is the difference between extrafusal and intrafusal muscle fibres?

A

extrafusal muscle fibres are normal skeletal muscles fibres which are found outside muscle spindles.
intrafusal muscle fibres are muscle fibres found within muscle spindles.

20
Q

what do gamma motor neurons control and innervate?

A

innervates intrafusal muscle fibres

controls fine motor movements

21
Q

what do alpha motor neurons control and innervate?

A

innervate extrafusal muscle fibres

they cause muscle contraction

22
Q

what are muscle spindles and what do they do?

A

collections of 6-8 specialised muscle fibers that are located within the muscle mass
They act as specialised receptors that signal the length and rate of change of length (velocity) of the muscle

23
Q

what are 1a sensory afferents and what is their role?

A

these are sensory fibres which are found in the central portion of intrafusal fibres
They provide information about length and velocity of the muscle

24
Q

describe the relay of information to and from a muscle spindle fibre in alpha-gamma coactivation

A

The muscle starts off at rest at a certain length and has a constant firing rate of 1a afferent nerves.

The muscle is stretched which also causes the muscle spindle to stretches and the Ia afferent fires more strongly.

When the muscle is released from the stretch and contracts (shortens), the muscle spindle becomes slack, causing the Ia afferent to fall silent (as no tautness to signal about).

The muscle spindle is rendered insensitive to further stretches of muscle.

To restore sensitivity, gamma motor neurons fire and cause the spindle to contract, thereby becoming taut and able to signal the muscle length again.

25
Q

describe the knee jerk reflex

A

if you hit patellar tendon, muscle belly stretches and muscle spindle also stretches.
This stretch is detected by muscle spindles in quadriceps muscle and increases signal frequency via sensory afferent fibres.
the sensory neurons synapse with motor neurons in spinal cord which cause contraction of quadriceps muscle and relaxation of hamstring muscle.

26
Q

what do Golgi tendon organs signal about?

A

Golgi tendon organs signal information about the load or force applied to a muscle

27
Q

what are golgi tendon organs? What do they consist of and how do they function as part of the golgi tendon reflex?

A

Golgi tendon organs are specialised receptors that are located between the muscle and the tendon.

They consist of numerous collagen fibres. The organ is innervated by primary afferents called Group Ib fibers, which have specialized endings that weave in between the collagen fibres.

When force is applied to a muscle, the Golgi tendon organ is stretched, causing the collagen fibers to squeeze and distort the membranes of the primary afferent sensory endings. As a result, the afferent is depolarised, and it fires action potentials to signal the amount of force.

28
Q

list the 3 main modalities used to assess CNS function?

A

EEG (electroencephalography) - record electrical activity in the cortex
Nerve conduction studies and EMG (electromyography) - assess function of PNS, NM junction and nerve roots.
EP (evoked potentials) - response to sensory stimulation

29
Q

list the components of the peripheral nervous system

A 
Nerve roots
which form a: plexus
which run into: peripheral nerves
nueromuscular junction 
muscle body
30
Q

describe how the speed of nerve conduction would be assessed peripherally ?

A

Stimulate the median nerve and record electrical activity in muscle. Time between electrical stimulus and activity in muscle = latency

stimulate further up the arm e.g. lateral to biceps tendon and record the latency.

measure the distance between the 2 points of stimulus and use v = d/t to calculate speed of nerve conduction

31
Q

what would reduced amplitude of nerve conduction speed suggest?

A

axonal damage

32
Q

what would reduced speed of nerve conduction suggest?

A

demyelination

33
Q

what nerve is compressed in carpal tunnel syndrome?

A

median nerve

34
Q

what causes foot drop

A 
problem with tibialis anterior either due to:
trauma or compression of common peroneal nerve at fibular head
or
damage to sacral plexus
or
damage to sciatic nerve
or
L4/5 nerve root lesion
35
Q

what is Guillain barre syndrome and what are its clinical features?

A

immune reaction to an initial infection, destroy myelin sheaths.
Clinical features: weakness in all limbs (progresses over DAYS), previous infection, areflexia, no ocular involvement, speech and swallowing are normal

36
Q

what is myasthenia gravis and what are its clinical features?

A

autoimmune reaction again the ACh receptor

Clinical features: fatiguable weakness (progresses over WEEKS/MONTHS), head drop, difficulty swallowing, double vision in evening, ptosis, voice becomes quieter when speaking

37
Q

what are 2 conditions that cause chronic generalised weakness?

A

motor neuron disease

neuropathy

38
Q

what are 2 conditions that cause acute weakness?

A

Guillain barre syndrome

myasthenia gravis

39
Q

what is the neurophysiological test for epilepsy? what else is this tests useful for?

A

electroencephalography

used for deteriorating cortical function

40
Q

what are evoked potentials useful for?

A

useful in intraoperative monitoring

Y2 HNN (34 decks)

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