FMC Test 2 *Peripheral Nerve*

Question 1

In the nervous system, what constitutes as a Mechanical Interface?

Answer 1

Anything that resides next to the nervous system or any structures the nervous system passes through or under on its way to their target tissue

Examples:
- Tendon
- Muscle
- Bone
- Intervertebral Disc
- Ligaments
- Fascia
- Blood Vessels

Question 2

what are innervated tissues?

Answer 2

Any tissue innervated by the nervous system (However brain, parenchyma of lung, the liver, and articular cartilage do NOT have nociceptive innervation)

• Virtually all tissues are innervated

Question 3

What is the function of the nervous system?

Answer 3

To provide communication while adapting to movement
- Its designed to tolerate a certain amount of mechanical loading through tension, compression and sliding

Question 4

What are types of stresses the nervous system may experience? (4)

Answer 4

• Immobilization
• Repetitive/Friction
• Compression
• Lengthening/Stretching

Question 5

In the nervous system, what is sliding?

Answer 5

• Movement of neural structures relative to their adjacent tissues
  –Longitudinal sliding: “Side to side’
  –Transverse sliding: “Rotating”
  –Internal sliding: Movement internally between
  connective tissue and neural tissue

Question 6

In the nervous system what is tension?
What is perineurium?
What are the effects of tension?

Answer 6

Elongation of the nerve

Perineurium:
- Primary protector of excessive tension tension
- Elastic property
- 18-22% elongation before failure

Tension Effects:
- At 8% elongation, flow of venous blood from nerves diminishes
- AT 15% all circulation is obstructed

(Extra info, idk if we need)
If a body part is moved and the other body parts are in neutral position, there will be much less tension and more movement of the nervous system

Conversely, if the same movement were performed with body parts in tension, there will be greater increase in intraneural tension, but little movement of the nervous system

Question 7

What are the transmission of forces on nerves?

Answer 7

• Resting nerve - Undulated (Nerve is in slack)
• Early Movement - Taking up slack
• Mid Range - Sliding effects
• End Range - Tension effects

Question 8

In the nervous system, what is compression?
What is Epineurium?
What are the effects of compression?

Answer 8

Distortion/changes of shape of neural structures according to pressures exerted on them

Epineurium:
- Primary protector against excessive compression
- Spongy quality

Compression Effects:
- The failure threshold for compression is 30-50 mmHG reduces venous flow from nerve
(The greater the pressure can lead to hypoxia, impairment of blood flow, conduction, and axonal transport)
- Over one hour and the nerve fails

(Extra info, idk if we need)
Symptoms may include pain, burning, paresthesias (Abnormal sensation), dysesthesias (unpleasant abnormal sensation), numbness and if prolonged, may lead to anesthesia (absence of pain) and loss of motor function. If the compression is on the NERVE ROOT, we would perform sensory testing in a dermatomal area and motor function in a myotomal area

Question 9

What is Transverse Contraction?

Answer 9

Physical stress placed on a peripheral nerve. Tensile stress applied longitudinally to peripheral nerve, creates an elongation of the nerve and increases in strain.
- The transverse contraction that occurs during the elongation is greatest at the middle of the section undergoing tensile strength

Question 10

In the Viscoelastic behavior of nerves, what are the 3 involved systems?

Answer 10

1) Mechanical Interface
2) Neural structures
3) Innervated tissue

Question 11

In the Viscoelastic behavior of nerves, what are the 3 Mechanical Functions?

Answer 11

1) Tension
2) Sliding
3) Compression

Question 12

In the Viscoelastic behavior of nerves, describe Intraneural Blood Flow.

Answer 12

• Its sensitive to oxygen deprivation
• Nerve has its own innervation: Nervi nervorum (This senses noxious, mechanical, chemical or thermal input)
• Source of nociception/pain
• Can cause intraneural inflammation/edema
  (This can lead to neurogenic Inflammation)

Question 13

In the Viscoelastic behavior of nerves, what is Neurogenic Inflammation?

Answer 13

• A sensitized nerve, can produce inflammation into its innervated tissue
• Can lead to tissue inflammation, trigger points, joint degeneration

Question 14

What is the Physical Stress Theory?

Answer 14

Its in relation with Tension, Compression and sliding.
- Nerves that are in the “Functional Zone”, are nerves receiving a sufficient amount of stress to maintain a state of equilibrium and normal function.

Question 15

In the Physical Stress Theory, what happens if a nerve is under prolonged Low Stress?

Answer 15

• This reduces the ability of the tissues to tolerate subsequent stresses even of previously normal levels

Question 16

In the Physical Stress Theory, what happens if a nerve is under the condition of High Stress?

Answer 16

The functional zone of the theory may expand, improving the ability of the tissue to tolerate subsequent physical stress.

Question 17

In the physical stress theory, what happens if a nerve is exposed to prolonged or repeated excessive stress?

Answer 17

The “functional zone” may shrink, Although scarring of damages tissue may enable the nerve to tolerate subsequent physical stresses, they physiological function of the nerve will be reduced.

Question 18

In the physical stress theory, what happens is a nerve is exposed to Extreme stress?

Answer 18

This will result in disruption of axon continuity or neural death and significantly reduce physiological function