FMC Test 2 *Peripheral Nerve* Flashcards
In the nervous system, what constitutes as a Mechanical Interface?
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
what are innervated tissues?
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
What is the function of the nervous system?
To provide communication while adapting to movement
- Its designed to tolerate a certain amount of mechanical loading through tension, compression and sliding
What are types of stresses the nervous system may experience? (4)
- Immobilization
- Repetitive/Friction
- Compression
- Lengthening/Stretching
In the nervous system, what is sliding?
- 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
In the nervous system what is tension?
What is perineurium?
What are the effects of tension?
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
What are the transmission of forces on nerves?
- Resting nerve - Undulated (Nerve is in slack)
- Early Movement - Taking up slack
- Mid Range - Sliding effects
- End Range - Tension effects
In the nervous system, what is compression?
What is Epineurium?
What are the effects of compression?
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
What is Transverse Contraction?
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
In the Viscoelastic behavior of nerves, what are the 3 involved systems?
1) Mechanical Interface
2) Neural structures
3) Innervated tissue
In the Viscoelastic behavior of nerves, what are the 3 Mechanical Functions?
1) Tension
2) Sliding
3) Compression
In the Viscoelastic behavior of nerves, describe Intraneural Blood Flow.
- 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)
In the Viscoelastic behavior of nerves, what is Neurogenic Inflammation?
- A sensitized nerve, can produce inflammation into its innervated tissue
- Can lead to tissue inflammation, trigger points, joint degeneration
What is the Physical Stress Theory?
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.
In the Physical Stress Theory, what happens if a nerve is under prolonged Low Stress?
- This reduces the ability of the tissues to tolerate subsequent stresses even of previously normal levels