Soft tissue

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Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue_sentence_0

Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, fat, fibrous tissue, skin, lymph and blood vessels, fasciae, and synovial membranes. Soft tissue_sentence_1

It is sometimes defined by what it is not – such as "nonepithelial, extraskeletal mesenchyme exclusive of the reticuloendothelial system and glia". Soft tissue_sentence_2

Composition Soft tissue_section_0

The characteristic substances inside the extracellular matrix of soft tissue are the collagen, elastin and ground substance. Soft tissue_sentence_3

Normally the soft tissue is very hydrated because of the ground substance. Soft tissue_sentence_4

The fibroblasts are the most common cell responsible for the production of soft tissues' fibers and ground substance. Soft tissue_sentence_5

Variations of fibroblasts, like chondroblasts, may also produce these substances. Soft tissue_sentence_6

Mechanical characteristics Soft tissue_section_1

At small strains, elastin confers stiffness to the tissue and stores most of the strain energy. Soft tissue_sentence_7

The collagen fibers are comparatively inextensible and are usually loose (wavy, crimped). Soft tissue_sentence_8

With increasing tissue deformation the collagen is gradually stretched in the direction of deformation. Soft tissue_sentence_9

When taut, these fibers produce a strong growth in tissue stiffness. Soft tissue_sentence_10

The composite behavior is analogous to a nylon stocking, whose rubber band does the role of elastin as the nylon does the role of collagen. Soft tissue_sentence_11

In soft tissues, the collagen limits the deformation and protects the tissues from injury. Soft tissue_sentence_12

Human soft tissue is highly deformable, and its mechanical properties vary significantly from one person to another. Soft tissue_sentence_13

Impact testing results showed that the stiffness and the damping resistance of a test subject’s tissue are correlated with the mass, velocity, and size of the striking object. Soft tissue_sentence_14

Such properties may be useful for forensics investigation when contusions were induced. Soft tissue_sentence_15

When a solid object impacts a human soft tissue, the energy of the impact will be absorbed by the tissues to reduce the effect of the impact or the pain level; subjects with more soft tissue thickness tended to absorb the impacts with less aversion. Soft tissue_sentence_16

Soft tissues have the potential to undergo large deformations and still return to the initial configuration when unloaded, i.e. they are hyperelastic materials, and their stress-strain curve is nonlinear. Soft tissue_sentence_17

The soft tissues are also viscoelastic, incompressible and usually anisotropic. Soft tissue_sentence_18

Some viscoelastic properties observable in soft tissues are: relaxation, creep and hysteresis. Soft tissue_sentence_19

In order to describe the mechanical response of soft tissues, several methods have been used. Soft tissue_sentence_20

These methods include: hyperelastic macroscopic models based on strain energy, mathematical fits where nonlinear constitutive equations are used, and structurally based models where the response of a linear elastic material is modified by its geometric characteristics. Soft tissue_sentence_21

Pseudoelasticity Soft tissue_section_2

Even though soft tissues have viscoelastic properties, i.e. stress as function of strain rate, it can be approximated by a hyperelastic model after precondition to a load pattern. Soft tissue_sentence_22

After some cycles of loading and unloading the material, the mechanical response becomes independent of strain rate. Soft tissue_sentence_23

Despite the independence of strain rate, preconditioned soft tissues still present hysteresis, so the mechanical response can be modeled as hyperelastic with different material constants at loading and unloading. Soft tissue_sentence_24

By this method the elasticity theory is used to model an inelastic material. Soft tissue_sentence_25

Fung has called this model as pseudoelastic to point out that the material is not truly elastic. Soft tissue_sentence_26

Residual stress Soft tissue_section_3

In physiological state soft tissues usually present residual stress that may be released when the tissue is excised. Soft tissue_sentence_27

Physiologists and histologists must be aware of this fact to avoid mistakes when analyzing excised tissues. Soft tissue_sentence_28

This retraction usually causes a visual artifact. Soft tissue_sentence_29

Fung-elastic material Soft tissue_section_4

Fung developed a constitutive equation for preconditioned soft tissues which is Soft tissue_sentence_30

with Soft tissue_sentence_31

Isotropic simplification Soft tissue_section_5

where a, b and c are constants. Soft tissue_sentence_32

Simplification for small and big stretches Soft tissue_section_6

For small strains, the exponential term is very small, thus negligible. Soft tissue_sentence_33

On the other hand, the linear term is negligible when the analysis rely only on big strains. Soft tissue_sentence_34

Gent-elastic material Soft tissue_section_7

Further information: Gent (hyperelastic model) Soft tissue_sentence_35

Remodeling and growth Soft tissue_section_8

Soft tissues have the potential to grow and remodel reacting to chemical and mechanical long term changes. Soft tissue_sentence_36

The rate the fibroblasts produce tropocollagen is proportional to these stimuli. Soft tissue_sentence_37

Diseases, injuries and changes in the level of mechanical load may induce remodeling. Soft tissue_sentence_38

An example of this phenomenon is the thickening of farmer's hands. Soft tissue_sentence_39

The remodeling of connective tissues is well known in bones by the Wolff's law (bone remodeling). Soft tissue_sentence_40

Mechanobiology is the science that study the relation between stress and growth at cellular level. Soft tissue_sentence_41

Growth and remodeling have a major role in the cause of some common soft tissue diseases, like arterial stenosis and aneurisms and any soft tissue fibrosis. Soft tissue_sentence_42

Other instance of tissue remodeling is the thickening of the cardiac muscle in response to the growth of blood pressure detected by the arterial wall. Soft tissue_sentence_43

Imaging techniques Soft tissue_section_9

There are certain issues that have to be kept in mind when choosing an imaging technique for visualizing soft tissue extracellular matrix (ECM) components. Soft tissue_sentence_44

The accuracy of the image analysis relies on the properties and the quality of the raw data and, therefore, the choice of the imaging technique must be based upon issues such as: Soft tissue_sentence_45

Soft tissue_ordered_list_0

  1. Having an optimal resolution for the components of interest;Soft tissue_item_0_0
  2. Achieving high contrast of those components;Soft tissue_item_0_1
  3. Keeping the artifact count low;Soft tissue_item_0_2
  4. Having the option of volume data acquisition;Soft tissue_item_0_3
  5. Keeping the data volume low;Soft tissue_item_0_4
  6. Establishing an easy and reproducible setup for tissue analysis.Soft tissue_item_0_5

The collagen fibers are approximately 1-2 μm thick. Soft tissue_sentence_46

Thus, the resolution of the imaging technique needs to be approximately 0.5 μm. Soft tissue_sentence_47

Some techniques allow the direct acquisition of volume data while other need the slicing of the specimen. Soft tissue_sentence_48

In both cases, the volume that is extracted must be able to follow the fiber bundles across the volume. Soft tissue_sentence_49

High contrast makes segmentation easier, especially when color information is available. Soft tissue_sentence_50

In addition, the need for fixation must also be addressed. Soft tissue_sentence_51

It has been shown that soft tissue fixation in formalin causes shrinkage, altering the structure of the original tissue. Soft tissue_sentence_52

Some typical values of contraction for different fixation are: formalin (5% - 10%), alcohol (10%), bouin (<5%). Soft tissue_sentence_53

Imaging methods used in ECM visualization and their properties. Soft tissue_sentence_54

Soft tissue_table_general_0

Soft tissue_cell_0_0_0 Transmission LightSoft tissue_cell_0_0_1 ConfocalSoft tissue_cell_0_0_2 Multi-Photon Excitation FluorescenceSoft tissue_cell_0_0_3 Second Harmonic GenerationSoft tissue_cell_0_0_4 Optical coherence tomographySoft tissue_cell_0_0_5
ResolutionSoft tissue_cell_0_1_0 0.25 μmSoft tissue_cell_0_1_1 Axial: 0.25-0.5 μm

Lateral: 1 μmSoft tissue_cell_0_1_2

Axial: 0.5 μm

Lateral: 1 μmSoft tissue_cell_0_1_3

Axial: 0.5 μm

Lateral: 1 μmSoft tissue_cell_0_1_4

Axial: 3-15 μm

Lateral: 1-15 μmSoft tissue_cell_0_1_5

ContrastSoft tissue_cell_0_2_0 Very HighSoft tissue_cell_0_2_1 LowSoft tissue_cell_0_2_2 HighSoft tissue_cell_0_2_3 HighSoft tissue_cell_0_2_4 ModerateSoft tissue_cell_0_2_5
PenetrationSoft tissue_cell_0_3_0 N/ASoft tissue_cell_0_3_1 10 μm-300 μmSoft tissue_cell_0_3_2 100-1000 μmSoft tissue_cell_0_3_3 100-1000 μmSoft tissue_cell_0_3_4 Up to 2–3 mmSoft tissue_cell_0_3_5
Image stack costSoft tissue_cell_0_4_0 HighSoft tissue_cell_0_4_1 LowSoft tissue_cell_0_4_2 LowSoft tissue_cell_0_4_3 LowSoft tissue_cell_0_4_4 LowSoft tissue_cell_0_4_5
FixationSoft tissue_cell_0_5_0 RequiredSoft tissue_cell_0_5_1 RequiredSoft tissue_cell_0_5_2 Not requiredSoft tissue_cell_0_5_3 Not requiredSoft tissue_cell_0_5_4 Not requiredSoft tissue_cell_0_5_5
EmbeddingSoft tissue_cell_0_6_0 RequiredSoft tissue_cell_0_6_1 RequiredSoft tissue_cell_0_6_2 Not requiredSoft tissue_cell_0_6_3 Not requiredSoft tissue_cell_0_6_4 Not requiredSoft tissue_cell_0_6_5
StainingSoft tissue_cell_0_7_0 RequiredSoft tissue_cell_0_7_1 Not requiredSoft tissue_cell_0_7_2 Not requiredSoft tissue_cell_0_7_3 Not requiredSoft tissue_cell_0_7_4 Not requiredSoft tissue_cell_0_7_5
CostSoft tissue_cell_0_8_0 LowSoft tissue_cell_0_8_1 Moderate to highSoft tissue_cell_0_8_2 HighSoft tissue_cell_0_8_3 HighSoft tissue_cell_0_8_4 ModerateSoft tissue_cell_0_8_5

Disorders Soft tissue_section_10

Soft tissue disorders are medical conditions affecting soft tissue. Soft tissue_sentence_55

Often soft tissue injuries are some of the most chronically painful and difficult to treat because it is very difficult to see what is going on under the skin with the soft connective tissues, fascia, joints, muscles and tendons. Soft tissue_sentence_56

Musculoskeletal specialists, manual therapists and neuromuscular physiologists and neurologists specialize in treating injuries and ailments in the soft tissue areas of the body. Soft tissue_sentence_57

These specialized clinicians often develop innovative ways to manipulate the soft tissue to speed natural healing and relieve the mysterious pain that often accompanies soft tissue injuries. Soft tissue_sentence_58

This area of expertise has become known as soft tissue therapy and is rapidly expanding as the technology continues to improve the ability of these specialists to identify problem areas more quickly. Soft tissue_sentence_59

A promising new method of treating wounds and soft tissue injuries is via platelet growth factor (PGF). Soft tissue_sentence_60

There is a close overlap between the term "soft tissue disorder" and rheumatism. Soft tissue_sentence_61

Sometimes the term "soft tissue rheumatic disorders" is used to describe these conditions. Soft tissue_sentence_62

See also Soft tissue_section_11

Soft tissue_unordered_list_1

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: tissue.