Osteopathic Reflexes Flashcards
Define a myotactic reflex
Tonic contraction of the muscles in response to a stretching force, due to stimulation of muscle receptors
T/F: Some dorsal horn neurons respond to visceral as well as somatic stimuli
True
What area of the spinal cord processes information?
Gray matter
What is the grey matter of the spinal cord divided into?
Rexed layers 1-10; upper layers are 1-6
Afferents from body synapse here
What is the function of layer 3 and 4 of the grey matter?
Mechanoreceptors
What is the function of layers 1 and 5 of the grey matter?
A-delta fast pain fibers
What is the function of layer 2 in the grey matter?
Small C fibers of slow pain
What is found in the lower layers of the grey matter?
Inter neurons and motor neuron cell bodies
Where do afferent fibers (visceral and somatic) mostly end?
1 and 5
What percentage of inter neurons receive input from both visceral and somatic afferents?
70-80%
T/F: Musculoskeletal palpatory findings may correlate with visceral disturbances
True
This is the somatic component of disease
Define sensitization
Stable response level is reached to a repeated stimulus that can continue but not change in intensity as long as the stimulus is continued
Define habituation
Process of decreasing response of a neural pathway with a continuous stimulation; opposite of sensitization
What is the nociception theory?
Once a stimulus is strong enough to activate (depolarize) nociceptive pathways, impulses travel to the cord and then branch to multiple sites; results in release of peptides at the motor neuron level in the peripheral tissues
No nociceptors in brain or hyaline cartilage
Define facilitation
Maintenance of a pool of neurons in a state of sub threshold excitation; less afferent stimulation is required to trigger the discharge of impulses
The peptides released in a nociceptive pathway initiate the release of what?
Prostaglandins, bradykinins, etc.; results in lowering nociceptor thresholds, thus increasing input to the cord
What does inflammation do to the balance between sensitization and habituation?
Disrupts the balance and results in larger than normal motor outputs to the autonomics and somatic systems; this is thought to set up the low-threshold spinal reflexes called “the facilitated segment”
Define short term excitability (sensitization)
1-2 seconds of afferent input; excitability lasts for 90-120 seconds
Define long term sensitization
Inputs of several minutes; excitability lasts for hours
Define fixation
15-40 minutes of afferent input; excitability lasts for days or weeks
Define permanent excitability
Input lasts forever? - long time; death of inhibitory inter neurons
Who was the first to show reflex changes using EMG?
Denslow
What did Denslow find?
Found long-lasting, low threshold areas to afferent inputs; stimulus was same level, other spinal levels, and psychological stress; Denslow correlated these excitable areas with injury and disease
What is the facilitated segment concept?
Korr suggested these low threshold spinal reflexes represented pathways in a hyper-excited state by a continuous bombardment of inputs
What makes up the facilitated segment?
Skeletal muscle and the sympathetic nervous system
What is allostasis?
Stimulus (insult) applied to tissues; develop chemical soup of inflammation that causes primary afferent sensitization; results in hyperalgesia (exaggerated response to a noxious stimulus)