Neural Systems Flashcards
what are the 2 main types of structural components of a nerve
neural / conductive tissue
connective / protective tissue
what do neural / conductive tissues in the nerve do
take neuro signals to ms
what are examples of neural/conductive tissues
axons
schwann cells
myelin sheaths
what does the connective/protective tissue of a nerve do
mechanical properties to support and protect the nerve
how does connective/protective tissue vary between the CNS and PNS
more connective/protective tissue in peripheral nerves
nervi nervorum vs vasomotor innervation
nervi nervorum - intrinsic
- nerve is source of pain itself
vasomotor - extrinsic from autonomic fibers
- innervation of dilation/constriction of blood vessels
what is and where does the blood supply for the nerve come from
vasa nervorum
travels internally and externally
how susceptible are nerves to blood loss or ischemic events? why?
very
nerves are blood thirsty
- uses 20% of body’s available O2
what is pia mater
innermost meningeal layer surrounding spinal cord and forming a barrier b/w CSF and cord
what is arachnoid mater
middle layer
encloses sub-arachnoid space containing CSF
what is dura mater
outer layer continuous w epineurium
strongest connective tissue in CNS
elastic properties allows for some stretching but prevents too much stretching
what are superior and inferior attachments for dura mater
superior - cranial bones
inferior - coccyx
what are lateral attachments for dura matter
transverse processes of verebrae via meningo-vertebral ligaments
what ms does dura mater attach to
rectus capitus posterior ms b/w occiput and atlas
what are 4 neural tension tests that can put tension across nervous system based on CNS connective tissue attachments
slump
ntpt
slr
ccft
why are there more layers of connective tissue in the PNS than the CNS
less bony protection like the CNS has
endoneurium: functions
supports nerve fibers
transmits capillaries
mechanical properties support both tensile strength and elasticity
- resists some stretching but allows some (more than the CNS)
perineurium: structure, functions
encircles form fascicles
high tensile strength and minimal elasticity barrier restricts diffusion, protecting the nerve from chemical insult
- important if there is nearby inflammation
epineurium: structure, function
encircles fascicles contains blood (vasa nervorum) and lymph vessels
function is to cushion entire nerve from external compressive forces
what is the overall structure of a PNS nerve and how does this lend to peripheral nerves having less bony protection than CNS
on average 1/2 of nerve is connective tissue to protect it
- varies w nerve location as nerves needing to tolerate more compression have more connective tissue
what nerve tolerates compression better without being source of pain
sciatic n.
how do mechanical properties of the nerve protect the nerve
accommodate to stress and strain of mvmt
describe the concept of the nerve being on slack and its role in protecting the nerve
undulations absorb traction forces
- when slack in system can absorb traction force
accommodates lengthening w/o tensing the nerve
how is the course that peripheral nerves take relative to joints protective in their function
most nerves travel in a flexor based pattern -> nervous system adapted to be slack when up tall and neutral
some do travel ext based (like ulnar n.)
what are 5 anatomical features which protect the nerve
mechanical properties
slack
course
presence of epineurium
ms tone
how does the presence of the epineurium protect the nerve
acts as cushion to nerve where peripheral nerves are subjected to compressive forces
- ex: sciatic > ulnar
how does ms tone protect the nerve
heightened ms response (flexor withdrawal) is noted when neural tissue is source of nociception
- nerve becomes mechanosensitive
why HS hurts w sciatic n. issues
what is neural tissue provocation testing truly testing
ms reactivity, not neural extensibility
why are nerve roots more susceptible to pain compared to peripheral nerves
5x less connective tissue
- dura/arachnoid mater, CSF
why is pain likely the first sx w an insult at the nerve root
inc susceptibility to stretch, compression injury, and chemical injury
- experience pain before sensory and strength
peripherally: if you sit on foot and falls asleep, sensory and strength sx before pain
how does a compressive mechanical insult cause pain/nociception
- prolonged compression of n. causes dec/loss of blood flow (intraneural microcirculation)
- nerve tells vessels (vasa nervorum) to vasodilate and bring in more blood —> brings in acidic inflammatory soup
- more fluid = more swelling and intraneural edema
- inc endoneurial fluid pressure -> dec in O2 -> ischemia
- ischemia leads to more inflammation and eventually nociception
–>sensitized structure (which is nerve) becomes ischemic and leads to nociception
why does tension/traction have a similar effect as compression
when you pull, dec space and causes compression
what is your patient education for someone who tells you stretching their HS makes their sciatic n. pain better initially and worse later
better initially bc get immediate mechanic receptor activation that makes it feel better
but as you stretch, put compression across nerve
- nerve has blood supply
- you cut blood supply off
- less blood = less O2
this process takes longer to get to brain to tell you it isn’t good than it does when the mechanoreceptors tell you the stretch feels good
feels good now, worse in the long run
peripheral nerve response to mechanical insult
loss of sensation and strength w/o pain + ischemia, eventually ischemia turns into nociception
compression does’t cause pain bc of protective connective tissue, unless compression in prolonged which will trigger an inflammatory cascade
nerve root response to mechanical insult
compression or chemical irritation causes pain d/t lack of protective connective tissue
- first sx = primary neurogenic pain
w sustained compression can get radiculopathy
what does it mean that neural tissue can become mechanosensitive
neural tissue is innervated and can be source of nociception
- when mechanically and/or chemically compromised
what does NTPTs assess
mechanoresensitivity of neural tissue by eliciting protective ms reactivity
what is pain behavior of neural tissue
latent response / worse at night
mvmt patterns avoid stretching nerve
primarily neurogenic pain patterns
- NR = dermatome
- peripheral = nerve map
how will ROM present w neural tissue on stretch
AROM = PROM
if there is pain w ROM, what do you want to do
try to sensitize the ROM
- move the neck/back, or moving distally
what are common palpatory findings in neural tissue as primary source of pain
hyperalgesic to nerve palpation and surrounding cutaneous tissues
what are 7 neural assessments
slump
slr
femoral n. tension test
median n. ntpt
ulnar n. ntpt
radial n. ntpt
nerve palpation
how is median n. ntpt sensitized
elbow ext
how is radial n. ntpt sensitized
elbow ext
how is ulnar n. ntpt sensitized
elbow flex
what landmark does the radial n. run through at the wrist
anatomical snuffbox
what landmark does the ulnar n. run through at the wrist
guyon’s canal
where does the median n. cross the wrist and describe nearby ms
just prox to carpal tunnel
b/w FCR and PL
why are active treatments typically not productive in neural treatment
may lead to central pain
- not changing threshold, just putting more input
- SHOULD NOT THINK no pain no gain
how can you change the compliance of the nervous system during neural treatment
put nerve on slack
what are neural treatment aims
protect the nerve - ed
improve compliance of NS
change mechanical interface
- avoid stretching the nerve
change pain pressure threshold
- think ab neurophysio response
what are 5 contraindications for neural treatment
progressive neuro condition
neuropathies
systemic disorders
treatment causes pain/ inc distal sx
nerve conduction deficit
what about progressive neuro conditions make it a contraindication for neural treatment
compression hasn’t been resolved and getting worse
- progressive myotomal weakness
- not changing no matter how much protection
why are neuropathies a contraindication for neural treatment and what is an example
pathologic changes to the nerve itself
- ex: diabetic neuropathy
what are examples of systemic disorders that are contraindications for neural treatment
MS
ALS
CA
HIV
why is neural treatment a contraindication if it causes pain or inc distal sx
don’t want to peripheralize sx
- always want to centralize sx
why is nerve conduction deficits a contraindication to neural treatment
if enough damage to nerve that there is dec EMG findings, then waiting for axonal growth and stretching/straining isn’t going to work
- axonal growth is slow
what are the main strategies to treating neural tension
education
change neurophysio response
med intervention
what do you educate the patient on when treating neural tension
position of ease/tape
- avoid positions which inc tension
active rest
avoid aggravating activities
- usually includes stretching
what are interventions we use to change the neurophysiological response
manual therapy
self treatment / neural glides
ms rehab
- patterning
- isolated activation (DNF, TrA, multifidi)
manual therapy treatment glides
gently mob structures near n.
pt in unloaded neural position
gentle slow oscillations - no sx
technique short of reactivity
- grade 1-2, joint mob for pain
when you assess ROM after a few reps what should you see and why
should make changes quickly bc its neurophysio effects
what TBC group isn’t appropriate for manual neural glides
sx modulation
manual neural treatment: neurophysio mechanism
modulates pain by activating descending inhibitory CNS to dec perception of pain
manual neural treatment: physio mechanism
motion helps to rebalance the pressure gradient intraneurally
aids in restoration of circulation and axoplasmic transport
normal motion, rebalances pressure gradient
manual neural treatment: mechanical mechanism
breaks adhesions (formed likely bc of chronicity) but is unable to do so until ms response and sensitivity are dec by inc threshold
flossing vs gliding
flossing - take tension from one side, dec tension from other side
gliding - repetetive tension
- ie bending and straightening elbow for median n.
what other ms rehab should be done w neural treatment (4)
isolated activation
patterning restore normal mvmt patterns
aerobic
stretching ? maybe
what ms should you work on isolated activation and why
DNF
TrA
multifidi
deep ms tend to be inhibited
what should be done throughout muscle rehabilitation in conjunction w neural treatment
reassessment of neural tissue compliance
what does it mean to patterning restore normal mvmt patterns
restoration of normal motion after is important bc it can cause a cycle which keeps aggravating pain
- you change the way you move bc of pain
what type of pain is aerobic activity best for
chronic
why is stretching often not indicated as an intervention
provocative and contraindicated if causes peripheral sx
- tends to make pt worse
- usually not indicated
