![]() ![]() Therefore, the results of elastography can show the presence and extent of fibrosis which can help in the choice of the best treatment.Ģ. The presence of fibrosis should result in harder regions with higher values of stiffness. For example, liver fibrosis is the formation of an abnormally large amount of scar tissue when the liver attempts to repair and replace damaged tissue. This information is useful for detecting the presence and severity of diseases. Medical imaging known as elastography is used to non-invasively map the viscoelastic properties of soft tissues inside the body. Human tissues such as skin, muscle, cardiac, and adipose tissues have their own specific viscoelasticity. The understanding of viscoelasticity in the human body is extremely important, mainly for the two reasons listed below:ġ. Differences in the tissue viscoelasticity can be related to the presence of diseases It will deform with the force and it will slowly return to its original state after the force is removed. A viscoelastic object will then show both types of responses. On the other side of the spectrum, a material can behave as an (elastic) solid capable of deforming under an applied force and returning instantly to its original state when the force is removed. Going into more details about viscoelastic behavior: on one side, a material can behave as a (viscous) fluid capable of flowing when submitted to a force. ![]() In other words, cells, tissues, and organs have a mix of viscous and elastic responses when submitted to mechanical forces and this viscoelastic response is part of their main physiological role. An important point to extract from this example is that all the components of our body show a viscoelastic behavior to some extent and this behavior is related to their function in the body. A heart attack, for example, can cause scar formation in the heart muscle, which leads to loss of muscular power and possibly heart failure. However, in internal tissues and organs, scars can compromise functioning. On the skin, this difference probably won’t cause major problems beyond esthetics. A scar has a clearly different appearance, texture, and often hardness than the surrounding tissue. Scars result from the biological process of wound repair that can happen in any organ or tissue of the body. Neurology,44,9,S12-20.If you look at any scar on your skin you will see a difference in viscoelasticity. Kinesiology: Application to pathological motion. ![]() Baltimore: Lippincott, Williams & Wilkins. Basic biomechanics of the musculoskeletal system. Scandinavian Journal of Rehabilitation Medicine, 30 (Sup), 19-32. Evaluation of and methods to change muscle tone. Movement dysfunction following central nervous system lesions: A problem of neurologic or muscular impairment. Stiffness due to voluntary muscle activity.cross-bridges in inactive actin-myosin produce thixotropy, so that a muscle's stiffness depends on its recent movement history.connective tissue has its own length-tension properties.The faster the rate of elongation, the stiffer the material's behavior. The passive length-tension curve of a viscous material has a slope that changes, increasing as the velocity of elongation increases. Highly viscous fluids are "thick" and flow more slowly than "thinner," less viscous fluids. ![]() Viscous materials resist elongation more at higher rates of elongation. In addition to displaying the property of elasticity, many tissues display viscosity, a resistance to flow. The knee's anterior cruciate ligament has a distinct length-tension curve. The distinctive stiffness properties of any soft tissue are illustrated by its length-tension curve. In Soderberg's figure, the stiffer the muscle, the steeper the slope of its passive stress-strain curve. Some are stiffer than others they develop more force during a given amount of elongation. 32) illustrates that muscles differ in their passive properties. Passive force, like active force, acts in a direction from the muscle’s points of attachment toward its center. This force is passive, since it exists whether or not the muscle is active. HUMAN TISSUES, INCLUDING MUSCLES, BEHAVE LIKE SPRINGS THEY ARE ELASTIC.Īt lengths greater than their resting length (l 0), they develop tension or force. PASSIVE FORCE Development of passive (viscoelastic) force ![]()
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