Difference Between Aponeurosis and Tendon

The human body is, without a doubt, the most complicated system on the planet. There are innumerable body components, hundreds of bones, numerous muscles, and everything in between.

In this intricate framework, there are several components that appear to be very similar to the average individual. However, if one looks closely, they can be distinguished. 

The Tendons and Aponeurosis are two components of the human body that are associated with the muscles. While these two can be confusing, there is a significant distinction between them. 

Aponeurosis vs Tendon 

The difference between an Aponeurosis and a Tendon is that the former connects the body’s muscles to other muscles that need assistance, whilst the latter acts as a link between bones and muscles. These two perform two distinguished functions related to muscles. These contribute to the better functioning of the body.  

An Aponeurosis is basically a sheet-like tissue that works as a connector between those muscles which are in need of such connection. These tissues can be found largely in the areas of the abdomen or palm of the hands. Aponeurosis also joins a muscle with a segment of skin. It reflects gleaming- white color.

A Tendon, on the other hand, is essentially a muscle extension that connects the muscle to another bone. It has a tough structure and is shaped somewhere in a round manner.

Tendon is a very important part of the muscle because it contracts and stretches to smooth out the movement of the body. It gives the muscle a chance to relax while also completing the activity.  

Comparison Table

Parameters of Comparison	Aponeurosis	Tendon
Meaning	Aponeurosis is a sort of muscle connector, which joins the muscles with various muscles and skin segments.	Tendon is a type of muscle connector, performing the function of connecting muscles with related bones.
Shape	Having the shape of a sheet made up of many tissues	A round-shaped tissue
Structure	Delicate	Tough
Function	To join one muscle with other muscles or sometimes with certain parts of skin too.  To keep the body stable and strong.	To join one muscle with a bone.  To assume the pressure while the body performs an activity. To not let the muscles get stressed.
Found in	Mostly in the abdomen and palms.	Mostly in the heel area or shoulder.
Strength	Hardly injured.	Easily injured

What is Aponeurosis? 

An aponeurosis is a collection of cells with identical characteristics and functions. This tissue’s primary job is to support the bodily structure during movement and, on occasion, to connect certain muscles to other muscles or bones. Aponeurotica is another term for this type of tissue. 

It is easy to distinguish it from other connective tissues in the body based on its structure. Its structure is made up of many layers of cells that act as a barrier between one another.

Because it is comprised of collagen, it resembles ligaments. Aponeurosis has a gleaming whitey-silverish appearance. Furthermore, this tissue is more sensitive than other tissues. 

It joins the muscles with other muscles and sometimes with bones too. But unlike Tendon, its primary function is to absorb shock and energy during the movement of muscles. In other words, Aponeurosis tolerates the pressure during such movement and enables the muscle to work efficiently.  

Traces of this tissue can be found in the whole body, but certain specific Aponeurosis tissues can be named-  

• Anterior Abdominal Aponeuroses 
• Posterior Lumbar Aponeuroses 
• Scalp Aponeuroses, etc. 

What is Tendon? 

Tendon can be termed as a tissue that joins the muscles and bones in order to facilitate the movements of the body. This tissue happens to be a part of the muscle itself and joins the muscles to other extensions wherever needed.  

This connective tissue’s primary job is to connect muscles and bones, and it absorbs all of the additional strain generated by muscular movement. The muscle performs smoothly as a result of the presence of this tissue.

Not only can energy be stored in this tissue, but it may also be retrieved later. This tissue is most commonly seen around joints, such as the heels, palms, and shoulders. 

This tissue has a structure resembling a rope, but sometimes its structure is flat also. This structure difference depends on the position of the tissue in the body. One thing here to be emphasized is that not every muscle is accompanied by a Tendon.  

Main Differences Between Aponeurosis and Tendon 

1. On one side, an Aponeurosis joins various muscles with other muscles, Tendon joins the muscle with another bone. 
2. The aponeurosis is a different structure attached to the bones and the muscles, while the Tendon itself happens to be the extension of the muscles. 
3. Aponeurosis has a flat shape, while Tendon has a structure of a rope. 
4. The aponeurosis is a delicate muscle connector, while Tendon is relatively rough. 
5. Aponeurosis has a function of absorbing energy during the movement of the muscle, while Tendon has a function of stretching and contracting during muscle movements. Tendon enables the muscle to work more efficiently without having the worry of stretches and contractions. 
6. It is very rare for the Aponeurosis to get injured as it is situated hidden under many layers of bones and muscles. But Tendon gets injured easily, for it is present in all the injury-prone areas.  
7. Aponeurosis has a shiny white appearance, while Tendon has a normal appearance, just like any other muscle.  

References

1. https://jamanetwork.com/journals/jamaophthalmology/article-abstract/632314  
2. https://www.tandfonline.com/doi/abs/10.3109/03008207809152283