Tendon or sin is a hard bone of fibrous connective tissue. It usually connects muscle to bone. Tendons similar to ligaments; Both are made of collagen. Strips join one bone to the other bone, while the tendons connect muscle to the bone perform the normal functioning of the body.


tendons functions

Traditionally, tendons have been thought of as a mechanism in which the muscles connect to the bone. It as well as the muscles themselves, which function to transfer forces.


This bone allows the tendons to passively appease the forces during movements, thus providing additional stability without active work. However, over the past two decades, extensive research has focused on the elastic properties of certain tendons and their ability to function as springs.


Not all tendons functions need to implement the same functionality. Its some limbs primarily position, such as fingers when writing (tendon tendons) and others acting as springs to make movement more efficient (energy storage tendons).


Energy storage crops can store and restore energy with high efficiency. For example, during a human step, the Achilles tendon stretch like a common ankle dorsiflexes. During the last part of the step, as plantar feet, the elastic energy store. Moreover, the muscle is able to function with less or even no change in length, allowing the muscle to generate greater strength.



The mechanical properties in tendons functions

The mechanical properties of the tendon depend on the collagen fiber diameter and orientation. Collagen fibers are parallel to each other and packed well, but they show a wave-like appearance due to planar glides or rulers on a scale of several micrometers.


In the tendons, collagen fibers have some elasticity due to the absence of hydroxyproline and proline residues in specific places in the amino acid sequence, which allows for the formation of other confirmations such as bending or inner helical coil loops and the development results of crimps.


In other tendons functions, The crimps of collagen fibrils allow tendons to have some flexibility as well as low compression stiffness. The tendon multi-stranded structure made up of many fibers and independent masks, it does not act as a single rod, and this feature also contributes to its flexibility.



Proteoglycan components

Proteoglycan components of the tendons are also important in mechanical properties. While collagen fibers allow tendons to resist tensile stress, proteoglycans allow them to withstand compression pressure.


These molecules are very hydrophilic, meaning they can absorb a large amount of water and therefore have a high swelling ratio. Since they connect regardless of the fracture, they may link and reduce the bridge so that the bridges between the fibers can be broken and refreshed.


This process may involve allowing fibril to extend and reduce diameter under stress. However, proteoglycans can also have a role in the tensile properties of the tendon. The tendon structure is actually a composite fibrous material, constructed as a series of hierarchical levels.


At each rank of the hierarchy, collagen units are bound together by collagen connections. The proteoglycans, to create a very durable tensile load structure.

The extension and strain of collagen fibers alone show to be much lower than the elongation and overall strain of the entire tendon under the same amount of stress, demonstrating that matrix-rich proteoglycan must also undergo deformation, and the hardening of the matrix occurs at high rates.


This distortion of the non-collagen matrix takes place at all levels of the tendon hierarchy, and by adapting the organization and the structure of this matrix. It is possible to obtain the different mechanical properties required by different tendons.


Energy storage crops illustrate to significant amounts of sliding between scales to allow for the high strain characteristics they require, while positional tendons rely more on sliding between fibers and collagen fibers.


However, recent data suggest that energy storage crops may also contain scales that deform, or helical, in nature – this arrangement would be very beneficial for providing spring-like behavior required for these tendons.




The leg tendons are very complex and complex. Therefore, the healing process of a broken tendon is long and painful. Most people who do not receive medical care within the first 48 hours of the injury will suffer from severe swelling, pain, and burning sensation at the site where the injury occurred.


It believes that tendons cannot undergo a matrix cycle and that the tenocytes were not able to repair. However, since it shows that over a person’s lifetime, active tensile tenocytes synthesize matrix components, as well as enzymes such as matrix metalloproteinases (MMPs), can degrade the matrix.


Tendons are capable of healing and recovery from injuries in a process controlled by the tenocytes and their surrounding extracellular matrix.