Ligaments and Tendons

What is a Ligament?

Ligaments are structures that help to hold two bones together and firmly adhere to them to form the joints in our body. A ligament contains a dense bundle of collagen fibres, a thick gel-like matrix and fibrocytes. 

Some ligaments are rich in collagen fibres and hence form the hard and sturdy backbone, while some ligaments are rich in elastin fibres and are flexible and non-sturdy.

Ligaments form a capsular sac at the ends of two bones that acts as an articulating surface and holds bones together. 

Our body has many different ligaments that include the articular ligament, The fibrous ligament, The periodontal ligament, the peritoneal ligament, etc.

What is a Tendon?

A tendon is a dense fibrous band of hard connective tissue that helps in the adhesion of a bone to a muscle. It helps in the transmission of Mechanical forces to the skeletal system without damaging or getting torn. Specialised fibroblasts called Tendon cells form the main cellular component of a tendon. 

Collagen fibres are arranged in a parallel manner and arranged in fascicles. A tendon is enclosed inside a fascia.

Approximately 85% of the cellular matrix of a tendon is formed by collagen fibres while the remaining 15% Contains extracellular components Like elastin, proteoglycans, Cartilage protein, and Inorganic components like calcium, magnesium, etc.

Type 1 collagen forms the bulk of a tendon, while other collagen fibres may also be present in small quantities. 

The major function of a tendon is to connect a bone with a muscle. However, a tendon performs other functions like acting as a positional tendon when we position our fingers to write, Acting as a spring for efficient locomotion by acting as energy-storing tendons.

Ligaments and Tendons: Difference 

Connection

The first and the most important difference between a ligament and a tendon is that a ligament joins two bones together while a tendon connects the bone to a muscle. Both of these contain fibroblasts that help in this connection.

Strength

Tendons are non-flexible and strong, whereas the ligaments are soft and elastic. Both of these play a very important role, and they are both composed of living cells.

Number

Every muscle will contain only a single tendon that will connect it to a bone, while every bone will have multiple ligaments that will aid to form a connection between two bones.

Colour

A tendon is generally white in appearance, while a ligament will appear yellow because of a varied composition of elastin and collagen fibres.

Arrangement of Fibroblasts

The fibroblasts in the case of a tendon are arranged in a straight line, while these fibroblasts are scattered without any particular pattern in a ligament. The fibres of a tendon are compact and are arranged in huge parallel bundles, while the fibres of a ligament are arranged in a bundle but are not packed compactly. 

Classification

Ligaments are classified into articular, peritoneal, and remnant ligaments. At the same time, there is no classification in the case of a tendon. However, tendons have been said to be of two broad categories, i.e. supporting tendon and energy storing tendon. A supporting tendon becomes functional when we use our fingers for writing and sewing, and other such purposes.

Conclusion

Tendons and ligaments are important connecting structures that help in the attachment and proper functioning of bones and muscles in our body. Blood supply is absent in both ligament and tendon. They are composed of similar components except for a few differences. Tendons are strong and non-flexible, while ligaments are soft and flexible. Ligaments can be classified as Peritoneal, articular and Remnant ligaments, while tendons can be of two types that are supporting tendons and energy-storing tendons.