Tendon

A tendon or sinew is a strong tissue that connects muscle to bone. It helps our bodies move by sending the force from muscle to the bones. This lets us bend, stretch, and do many things easily.

Tendons are made mostly of a protein called collagen. This gives them strength and flexibility. They are different from ligaments, which connect bone to bone. Our bodies have about 4,000 tendons. They work together to help our muscles and bones.

Tendons can handle a lot of pulling without breaking. Learning about tendons shows us how our bodies work and why it is good to care for our muscles and bones with the right exercise and food.

Structure

A tendon is a strong tissue that connects muscle to bone. It is made of special cells called tendon cells. These cells make a substance called collagen.

Collagen fibers in tendons line up in the same direction. They are held together by thin layers of tissue. The whole tendon is covered by a layer of fascia.

Tendons are mostly made of collagen. This gives them strength. They also contain other materials that help them stay flexible. These include substances like elastin and proteoglycans. The collagen fibers in tendons come together to form larger structures. Proteoglycans help hold these fibers together. Tendon cells produce collagen and help the tendon respond to stretching and movement.

List of tendons

The human body has about 4,000 tendons. These strong tissues connect muscles to bones and help us move. A table shows 55 of these important tendons. This is just a small part of what our bodies use to stay strong and active.

Functions

Tendons are strong tissues that connect muscles to bones. They help us move by letting muscles pull on bones. Tendons can also store energy to make movement easier. For example, when we walk, the Achilles tendon in our heel stretches and then helps us take each step.

Tendons are made of a material called collagen. This gives them strength and flexibility. They can stretch a little and then return to their original shape, like tiny springs. This helps our muscles work better and gives us more control over how we move.

Clinical significance

Tendons can get hurt by doing too much activity. These injuries are called tendinopathies. They can make tendons weak or even break.

There are different kinds of tendinopathies. One is tendinosis, when the tendon gets damaged inside without swelling. Another is tendinitis, when the tendon gets inflamed and swollen.

When a tendon gets injured, it can still heal. Healing happens in three steps. First, the body sends special cells to clean up the injury. Then, the cells build new tissue to fix the tendon. Finally, the new tissue gets stronger and more like normal tendon tissue. With the right care and activity, tendons can recover and get stronger again.

Society and culture

Sinew, a strong material from tendons, was useful in old times before factories. People used it for sewing, attaching feathers to arrows, and making tools. It was especially important for Inuit and other cold-weather people who didn’t have other fibers. Some hunters used sinew in special bows.

Tendon is also eaten in some Asian foods. For example, beef tendon is a part of dishes like suan bao niu jin and can be found in Vietnamese phở.

Other animals

In some animals, like birds and certain dinosaurs, parts of the tendon can change into bone. This happens when special cells called osteocytes move into the tendon and start making bone. In birds, this mostly happens in the legs. In some dinosaurs, it helped support their tails.