Clinical Neurophysiology Flashcards
State the basic 3 types of information that spinal nerves contain?
Sensory
Motor
Autonomic
Origins of parasympathetic fibres?
- CN3,7, 9 and 10
- S2-S4
Origins of sympathetic fibrs?
T1-L2
very briefly describe the differences between a younger and older persons IVDs.
Young; Spongy, good shock absorbers
Older: Bit bony and cartilaginous
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?
Ages 20-55
L4/5 - lumbosacral in general. Although it can also affect cervical discs (C5/6 especially.
Thoracic
What parts of the IVD actually herniate? What effects can it have?
Seemingly the nucleus pulposus burts out of the anulus fibrosus (which is typically thinner posteriorly). Presses against nerve roots.
What is radiuclar pain? What is generaly the cause
- 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
In What direction do discs most comonly herniate?
Laterally
Discs can also herniate posteriorly - what pathology would you expect if this occured?
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) )
Describe sciatica
- Pain that radiates down the leg as a result of a nerve root problem (usually L5)
What region of the dorsal funiculus is for sensory infomration from the lower limb
Fasiculus gracilis
What region of the dorsal funiculus is responsible for carrying sensory information from the upper limb?
Fasiculus Cuneatus
Function of the spinocerebellar tract?
Conveys proprioception from limbs to the cerebellum
What pathway are the funiculus gracilis and the funiculus cuneatus
Dorsal meidal lemniscal pathway
Revision - What is the function of the Dorsal medial lemniscal pathway?
- Discriminitive touch
- Vibration
- Also a bit of proprioception
What does myelin do, and how does it do it?
- Maintains/increases the speed of signal transduction along nerves
- Is impermeable to ions, prevents ion leakage and ensures action potentials can be maintained
What special region of a myelinated axon can myelination take place?
Node of ranvier
How does an action potential travel along an axon? (think in terms of node of ranvier) What is this special process called?
- ction potentials are conducted from node to node,
- Salitatory conduction
Explain how current travels from one node of ranvier to another
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.
Explain the benefits of saltatory conduction
- 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
Definte motor unit
A lower motor neurone from the anterior horn of the spinal cord, and all of the nerve fibres that it innervates
GIve an example of a peripheral nerve disorder that affects motor function?
Myasthenia gravis
Guillane Barre Syndrome
Diabetic neuropathy
