Neurology

Question 1

3 main functions of spinal chord?

Answer 1

Carry motor information from brain to spinal segment

Carry sensory information from spinal segment to brain

Integration centre for certain reflexes

Question 2

Define dermatome

Answer 2

Area of skin supplied by a single spinal nerve root

Sensory function

Question 3

Define cutaneous distribution

Answer 3

Area of skin supplied by a cutaneous branch of a nerve

Sensory function

Question 4

Define myotome

Answer 4

Group of muscles supplied by a single spinal nerve root

Motor function

Question 5

Name the nerve plexus divisions from proximal to distal

Answer 5

Roots
Trunks
Divisions
Chords
Branches

Question 6

What are the main plexi?

Answer 6

Cervical
Brachial
Lumbar
Sacral

Question 7

What are the cutaneous areas of distribution UEX?

Answer 7

Axillary 
Medial cutaneous brachii
Cutaneous antibrachii medialis 
Musculocutaneous
Radial
Ulnar
Median

Question 8

Which dermatomes supply UEX?

Answer 8

C5-T2

Question 9

Where do dermatomes and myotome arise from?

Answer 9

Somites, divisions of the body of an embryo

Question 10

What myotomes innervate UEX?

Answer 10

C5-T1

Question 11

What dermatomes innervate LEX?

Answer 11

L1-S4

Question 12

What are the deep tendon reflexes, corresponding myotome relay and peripheral nerve?

Answer 12

Biceps brachii, C5, musculocutaneous
Brachioradialis, C6, radial
Triceps, C7, radial
Finger, C8, median and ulnar
Patella, L3-L4, femoral
Archillies, S1, sciatic

Question 13

Explain an excitory action potential?

Answer 13

If the membrane potential reaches a depolarisation threshold of -55mV, an excitatory action potential is generated, which will release neurotransmitters into the synaptic cleft which will depolarise the post synaptic neuron

If this depolarisation reaches threshold, the process is repeated on to the next post synaptic neuron

Question 14

Explain an inhibitory action potential?

Answer 14

Neurotransmitters released by the pre synaptic neuron will hyperpolarise the post synaptic neuron, making depolarisation by excitory synapse more difficult, greater depolarisation must occur to reach threshold

Question 15

How does a tract differ to a nerve?

Answer 15

Tracts are situated in CNS and do not have connective tissue coverings

Nerves are situated in PNS and have connective tissue coverings

Question 16

Explain white vs grey matter?

Answer 16

White matter consists of myelinated nerves/tracts, primarily axons that do not contain cell bodies, they are the “pathway” to the grey matter

Grey matter consists of non myelinated nerves/tracts, they are the “control centres” and are composed of cell bodies (and short distance connecting axons), only found in CNS or just outside spinal column (dorsal root ganglion)

Question 17

Explain muscle spindles?

Answer 17

intrafusal fibres; parallel to extrafusal (contractile) muscle fibres, contain sensory dendrites that detect size and speed of muscle length change.
Dendrites send impulse to spinal chord, which enacts a motor response to contract the stretched muscle (DTR) and relax antagonist muscle (reciprocal inhibition) to prevent over stretching

Question 18

Explain golgi tendon?

Answer 18

Continuous with extrafusal muscle fibres, in the tendon. Responds to tension

Question 19

Where are the cell bodies/grey matter of motor and sensory nerves located in the spinal chord?

Answer 19

Motor- deep spinal chord

Sensory- just outside each spinal segment (dorsal route ganglion)

Question 20

Define a nerve?

Answer 20

Bundle of fibres in the PNS with its own blood supply and innervation that transmits impulses between the CNS and the effector organ

Question 21

Explain the difference between stretch and glide of a nerve? (Neuro dynamic testing)

Answer 21

Stretch involves stretching the nerve at both proximal and distal ends

Glide involves stretching the nerve at either the proximal or distal end

Question 22

Define muscle tone and relationship between deep tendon reflex?

Answer 22

Muscle tone is the amount of resistance a muscle has in response to an externally applied stretch

Both are a contractile protective reaction to an externally applied stretch, the DTF is more rapid in terms of stretch application and consequent contraction

Question 23

What is hypo and hyper reflexia, and what may they indicate?

Answer 23

Hypo reflexia is lesser response to DTR, commonly associated with less muscle tone, indicates dysfunction within PNS

Hyper reflexia is a greater response to DTR, commonly associated with greater muscle tone, indicates dysfunction within CNS

Question 24

Explain the process of stretch/deep tendon reflex (DTR)?

Answer 24

Dendrites of muscle spindles sense a lengthening/stretch, this transmits an impulse directly to spinal chord which relays a motor impulse causing the muscle to rapidly contract.

This is the only monosynaptic pathway in the human body (involving only 2 neurons)
And serves as a rapid protective response to avoid overstretching.

Question 25

What would the motor, sensory and sensory-motor neurodynamic tests be?

Answer 25

Dermatome/cutaneous nerves can be tested with neurotips, for sensory function

Active muscle resisted tests are for motor function

Deep tendon reflex is both sensory and motor, as it requires sensory input to produce motor output