Clinical Neurophysiology

Question 1

State the basic 3 types of information that spinal nerves contain?

Answer 1

Sensory

Motor

Autonomic

Question 2

Origins of parasympathetic fibres?

Answer 2

• CN3,7, 9 and 10
• S2-S4

Question 3

Origins of sympathetic fibrs?

Answer 3

T1-L2

Question 4

very briefly describe the differences between a younger and older persons IVDs.

Answer 4

Young; Spongy, good shock absorbers

Older: Bit bony and cartilaginous

Question 5

Disc proplapse actually is more likely in younger patinets since it is still spongy and gelatinous. What age groups does it affect, and what vertebral levels does it occur? What level is rarely affected?

Answer 5

Ages 20-55

L4/5 - lumbosacral in general. Although it can also affect cervical discs (C5/6 especially.

Thoracic

Question 6

What parts of the IVD actually herniate? What effects can it have?

Answer 6

Seemingly the nucleus pulposus burts out of the anulus fibrosus (which is typically thinner posteriorly). Presses against nerve roots.

Question 7

What is radiuclar pain? What is generaly the cause

Answer 7

• Pain that occurs because of irritation of a sensitized nerve root
• usually but not exclusively because of a prolapsed intervertebral disc
• This pain is typically lancinating in quality, shooting down the leg like an electric shock. It affects a narrow band and has both deep and cutaneous components

Question 8

In What direction do discs most comonly herniate?

Answer 8

Laterally

Question 9

Discs can also herniate posteriorly - what pathology would you expect if this occured?

Answer 9

Compression of the spinal cord (technically if this is in the lumbo-sacral region, it will be pressing on the cauda equina - causing cauda equina syndrome) )

Question 10

Describe sciatica

Answer 10

• Pain that radiates down the leg as a result of a nerve root problem (usually L5)

Question 11

Answer 11

Question 12

What region of the dorsal funiculus is for sensory infomration from the lower limb

Answer 12

Fasiculus gracilis

Question 13

What region of the dorsal funiculus is responsible for carrying sensory information from the upper limb?

Answer 13

Fasiculus Cuneatus

Question 14

Function of the spinocerebellar tract?

Answer 14

Conveys proprioception from limbs to the cerebellum

Question 15

What pathway are the funiculus gracilis and the funiculus cuneatus

Answer 15

Dorsal meidal lemniscal pathway

Question 16

Answer 16

Question 17

Revision - What is the function of the Dorsal medial lemniscal pathway?

Answer 17

• Discriminitive touch
  
  • Vibration
  • Also a bit of proprioception

Question 18

What does myelin do, and how does it do it?

Answer 18

• Maintains/increases the speed of signal transduction along nerves
• Is impermeable to ions, prevents ion leakage and ensures action potentials can be maintained

Question 19

What special region of a myelinated axon can myelination take place?

Answer 19

Node of ranvier

Question 20

How does an action potential travel along an axon? (think in terms of node of ranvier) What is this special process called?

Answer 20

• ction potentials are conducted from node to node,
• Salitatory conduction

Question 21

Explain how current travels from one node of ranvier to another

Answer 21

electrical current flows through the surrounding extracellular fluid outside the myelin sheath, as well as through the axoplasm inside the axon from node to node, exciting successive nodes one after another. Essentially the nodes of ranvier allow for “re-generation” of the action potential.

Question 22

Explain the benefits of saltatory conduction

Answer 22

• Allows action potentials to “jump” and therefore cover distance more quickly
• More energy is conserved, as ions only transfer at the nodes. As such, less energy expenditure is required to re-establish baseline ion concentration after nerve impulses

Question 23

Definte motor unit

Answer 23

A lower motor neurone from the anterior horn of the spinal cord, and all of the nerve fibres that it innervates

Question 24

GIve an example of a peripheral nerve disorder that affects motor function?

Answer 24

Myasthenia gravis

Guillane Barre Syndrome

Diabetic neuropathy

Question 25

State sources of feedback about body position available to the CNS

Answer 25

• Muscle spindle i.e. muscle
• golgi tendon organ i.e. tendons
• Ligaments also

Question 26

Give an example of a condition where peripheral nerve innervation of muscles is disrupted. State the expected clinial presentation

Answer 26

Carpel tunnel syndrome - compression of median nerve

• Weakness in thumb, index, middle and part of ring finger, but not little finger.
• Tingling/numbness