Gel-to-sol model
Piezoelectric model
Stress strain curve
Viscoelastic properties of tissue
Stress strain curve: toe region
represents settling of the structure being tested, includes taking up slack
Stress strain curve: elastic zone
deformation within elastic group is reversible
Stress strain curve: plastic zone
usually results in permanent deformation
Stress strain curve: neck
after attaining ultimate stress the tissue begins to fail
* initally microfailure, tissues narrow (necking)
Stress strain curve: failure point
sudden decrease in stress while strain continues to rise
- decrease means that substance of the material has began to fail
Stress/Strain:Loading/ unloading
Stress/Strain: repeated loading
-stress/strain curve looks identical yet starts at the new length
Stress/Strain: creep
apply constant load to a structure and it lengthens over time
-greater length achieved with longer duration and less load
Stress/Strain: hysteresis
- increase in temp can affect mechanical properties of a structure
Stress/Strain: effects of speed
most substances stiffer with higher loading rates, will fail at higher stresses and lower strains (tear paper or tape quick)
Stress/Strain: effects of temp
Response of myofascial tissue to immobilization
Loss of ground substance
Traumatized vs untraumatized CT
Nontraumatized
- results in fibrosis
Traumatized
- results in scar tissue formation and contracture
Does the biomechanical model fit what we see in the clinic?
Muscle spindle type 1a receptors
Golgi type 1b receptors
Pacini and paciniform type II receptors
Ruffini type II receptors
Interstitial type III and type IV receptors (50% high threshold, 50% low threshold)
Mechanoreceptors and local fluid dynamics: interstitial (type III & IV)
Mechanoreceptors and local fluid dynamics: ruffini (type II)
inhibition of sympathetic activity