Muscles, tendons and ligaments: What are they?

Everyone knows what they are, right? Wrong!

Most people are familiar with muscles and why they exist. But tendons and ligaments too? Generally not. Many have a vague idea of what both are and maybe even where one could locate them. But their knowledge of the two highly necessary anatomical structures is a shaky terrain at best. Therefore, the aim of this post is to strengthen the foundations of our reader’s anatomy-related mental database and build a vault of valuable – and relative – information upon it.

To start off with the easiest, commonly known structure first, muscles connect bones to each other. Sometimes only two bones are attached to a single muscle, such as scapula (shoulder blade) and the humerus (upper arm bone) which are both connected on either end of the teres major muscle. Some muscles have multiple attachment points on different bones. An example of this can be found in the trapezius muscle, located on the back. This muscle joins the cranium (skull) and thoracic vertebrae (the spinal discs in the middle of the back) to the clavicle (collar bone) and scapula (shoulder blade). As mentioned in an earlier blog post, muscles have two main roles in the overall function of the body. The first is to enable movement and the second is to stabilise certain structures within its frame.

For more information about muscles in general, have a look at our previous post: Hijama and the Muscular System

trapezius.jpg1
The trapezius muscle is so big, it is often divided into three sections: upper, middle and lower (1)

Closer to the muscular system than one might initially think, tendons connect the ends of a muscle to a specific bone. In information booklets and health-related encyclopedias, they are usually white in colour and easily differentiated from the main body of a muscle. Tendons are made up of layers of strong connective tissue that run through the length of the muscle, allowing them to withstand the great amounts of force exerted upon them by bodily movements. Thus, bigger muscles tend to have thicker and sometimes longer tendons than smaller ones. One of the most well known tendons is the Achilles Tendon, which connects the soleus and gastrocnemius (calf muscles) to the calcaneus (heel bone). Not only are they capable of resisting the force of a contracting muscle, tendons relay that same force to the bone that they are attached to, resulting in movement of the body.

tendon
Aaaah, the infamous Achilles heel. I wonder if the person who linked it to weakness knew how much pressure tendons can withstand (2)

Though they may be comprised of fibrous connective tissues similar to those that form tendons, ligaments connect one bone to another. However, unlike muscles, ligaments are normally located where two bones meet to form a joint and exist to stabilise both. Due to its sturdy form, limbs are able to move in a free yet controlled manner. Whilst muscles propel them into action, ligaments prevent the limbs from moving in a way that could possibly cause severe damage to the body. Some of the most commonly injured ligaments include both the collateral and cruciate ligaments located within and on either side of the patellofemoral (knee) joint as well as those found around the glenohumeral (shoulder) joint. Once stretched or torn, ligaments are usually only fixed via surgery and sometimes even that cannot restore it’s former function.

Anterior view of knee joint comparing normal vs. damaged cartilage
The white thing labelled ACL is a ligament. The two non-transparent​ bands on either side of the knee cap are ligaments too (3)

To summarise it in a single paragraph, muscles, tendons and ligaments all play a part in keeping certain skeletal structures in a neutral position. Tendons and ligaments are made of the same kind of connective tissue and are both hard to tear. Once damaged, they can be hard and usually impossible to repair completely​. Muscles and tendons are closely interlinked and work together to facilitate bodily movement whereas ligaments are there to prevent an individual’s limbs from moving in harmful ways.

We hope that this information has benefited you, our dear readers, and we would love to hear from you. Comments, questions and weekly topic suggestions are always welcomed and greatly appreciated.

Thank you for reading!

The Pure Therapy Team

Images referenced from:
(1) nicktumminello.com/wp-content/uploads/2010/07/trapezius.jpg1.png
(2) differentialdiagnosislowerleg.weebly.com/uploads/5/4/7/6/54764553/8097310.jpg?382
(3) https://api.kramesstaywell.com/Content/ebd5aa86-5c85-4a95-a92a-a524015ce556/medical-illustrations/Images/amuscsk20140311v1001
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