What is a reflex in its very basic aspect?
you have an sensory afferent in –> directly responding is motor efferent out to the endpoint for a certain purpose.
What’s to note about some dorsal horn neurons?
they respond to visceral and somatic stimuli
In the spinal cord, where are most of the sensory aspects are coming in? (think layers)
where are the mechanoreceptors located?
what about the A(delta) fast pain fibers
what about the small C fibers of slow pain?
(Upper layers) Layers 1-6 of the Rexed Layers
Layers 1 and 5
What is in the lower layers of the rexed layers?
Motoneuron cell bodies and interneurons
Afferent fibers (visceral and somatic) always end mostly where?
layers 1 and 5
many areas overlap
from there they go cephalad for processing, or caudal.
70-80% of interneurons receive input from what?
what can this account for?
both visceral and somatic efferents
visceral pain being so diffuse and poorly localized and super localized pain with somatic efferents.
The overlap of the visceral and somatic afferent fibers is the basis for what?
what are two examples of it and why is it unique?
activation of the somatic muscle activity seen with visceral disturbances
visceral afferents activate sympathetic outflows and skeletal motor neurons (increase tone)
you can also reverse it too. somatic inputs alter sympathetic and parasymapthetic outflows
What’s to know about the descending influences on reflexes? (2 things)
they effect the long-lasting excitability of the outflows by maintaining the reflex ( interneurons acts as an amplifier of input hence more output would be expected)
can also inhibit somatic and autonomic outflows through these interneurons as well
clinical application of reflexes with the viscera and somatic systems?
visceral disturbances cause activation in the somatic musculature –> produces dysfunction at the facilitated segment
somatic disturbances can reflexly alter VISCERAL function
this all leads to the decompensation of homeostasis
What is the somatic component of disease?
what does this mean for OMT?
musculoskeletal palpatory findings that correlate with visceral disturbances
so we can normalize the MS component that helps normalize autonomic outflows so we can restore homeostasis
What are the steps for increasing sensitivity of the neurons?
Short term excitability – sensitization
*1-2 seconds of afferent input –> excitability lasts for 90-120s
long term sensitization
**inputs of several minutes –> excitability lasts for HOURS
15-40 minutes of afferent input that excitability lasts for days or WEEKS
Lasts forever(?) –> this can last for death of inhibitory interneurons.
Facilitated Segment Concept?
“low threshold spinal reflexes represented pathways in a hyper excited state by a continuous bombardment of inputs”
called a facilitated segment
so facilitated segments are interneurons that are constantly being excited.
Korr found that all diseases were accompanied by what (associated with facilitated segment concept)
hyper sympathetic tone.
3) what about both with this theory
Habituation –> process of decreasing response of a neural pathway with a continuous stimulation
Sensitization –> continuous stimulus gives you a wind up response to where it stops and maintains. (so goes up and stabilizes)
these two processes exist together to maintain a homeostasis preventing and over or under reaction to a stimulus
What causes nociception?
what happens because of this?
what is released?
what happens when this release happens?
how do we get pain?
how does this tie in with facilitated segment?
the idea is that alteration of nociceptive stimuli
sometiems the balance is shifted to the side of stimulation (facilitation).. once that stimulus (stretched muscle, fall, visceral problem) –> get a stimulus –> depolarization of nociceptive pathways –> to the afferents and branching to multiple sites going up and down the cord.
results in release of peptides at the motoneuron level at the peripheral tissues –> the peptides are the inflammatory cascade and initiate release of PGs, bradykinin, etc.
this results in lowering nociceptor thresholds thus increasing input to the cord. –> so way more pain, TART findings, somatic dysfunction.
low-threshold spinal reflex is the facilitated segment
Pain is what?
conscious perception of nociception
how does it happen?
long term neural effect of segmental facilitation.
stimulus comes in –> chemical soup of inflammation –> primary afferent sensitization –> results in hyperalgesia (exaggerated response to noxious stimuli)… ALLOSTASIS
What happens if the exaggerated response to noxious stimuli stays chronically?
you get secondary hyperalgesia –> called Central Sensitization
so neural pathways where these remain at the low level excitability threshold.
so doesn’t take much of a stimulus to fire this thing off again.
What happens in the dorsal horn neurons during allostasis?
effects Ca channels, phosphorylation cascades, lose inhibitory neuron function (filter becomes bad)
all aid in maintaining facilitation of the interneurons.
what happens if the facilitation is happening in the brainstem?
what does this affect?
what happens if you have long term facilitation here? what is the term?
it decreases the endogenous descending pathways including the AROUSAL SYSTEM
this lowers the catecholamines/glucocorticoids
long term facilitation damages this system
leads to loss of control of protective mechanisms called ALLOSTASIS OVERLOAD
effects on body systems affecting homeostasis
CV, Neuro, Immune problems
Osteopathic Reflex definitions:
stimulus from somatic –> effecting other part of the somatic system
somatic –>effecting visceral
stimulus from viscera effecting somatic
visceral stimulus effecting viscera
Somatosomatic reflex example?
Withdrawal response –> pulling away from heat.
Viscerovisceral reflex example?
eating food distends gut –> sends it to the brain and tells the organs to get some peristalsis going.
Somatovisceral reflexes examples? (3 spots)
Somatocardiac reflex –> twist ankle results in increase HR and BP
Somatogastric reflex –> pinching skin results in inhibition of peristalsis in the stomach.
Somatoadrenal reflex –> somatic stimuli causes release of catecholamines from adrenal medulla.
Viscerosomatic reflex examples
MI –> blocked heart –> pain in the left arm.
What is Chapman’s Points?
a group of palpable points occurring in predictable locations on the anterior and posterior surface of the body that are considered to be reflections of visceral dysfunction or disease.
what are the 3 component characteristics of chapman reflexes?
Gangliform contraction –> blocks lymphatic drainage and causes SNS dysfunction
What are you feeling for chapman points?
pea shaped things –> 2-3mm in size
dense but not hard.
located in the deep subcutaneous tissue
Chapman Reflex Dx / Testing
once found an isolated point –> apply gentle but firm pressure –> causes a deep, disagreeable pain response in the pt
sharp, non-radiating, pin-point.
clockwise or counterclockwise for 10-30 seconds
if mass disappears you’re done
Indications for Chapman’s?
Diagnosis –> screening exam when clinically indicated from patient history
treatment –> finding a CR that is possibly clinically relevant to the patient
Contraindications of Chapman’s?
emergent care, don’t do this, or patient refusal
fracture, cancer, patient instability
post-treatment precaution side effects of Chapmans?
discomfort, drink tons of water.