Tendons are like strong ropes that connect muscles to the bones, helping the limbs move when the muscles tighten and relax. However, tendons can get damaged due to overuse, injuries, aging, or conditions like arthritis. To keep the tendons healthy and strong, it's important to follow a balanced exercise routine that doesn’t strain them too much. This can help lower the risk of tendon problems and keep you moving comfortably.
Tendons are like strong, flexible ropes that connect the muscles to the bones, allowing for the movement of arms, legs, and other parts of the body. They also protect the muscles by absorbing some of the impact during running, jumping, or other movements or activities. The body has thousands of tendons, from head to toes. The largest one is the Achilles tendon, which connects the calf muscle to the heel. While tendons are strong and resistant to tearing, they aren’t very stretchy, making them prone to injury if overstretched. Healing from a tendon injury can take a long time.
When the muscles contract or tighten, the tendon pulls on the attached bone, making it move. Tendons act like levers, helping the bones move as muscles tighten and relax. Tendons are stronger and stiffer than muscles. For example, the tendons in the foot can handle more than eight times body weight, showing how strong they are!
Tendons are found throughout the body, connecting muscles to bones in places like the elbow, heel, knee, shoulder, and wrist.
Tendons may be of different shapes and sizes depending on which muscles they’re attached to. Wider and shorter tendons usually connect to muscles that generate a lot of force. Thinner and longer tendons usually connect to muscles that perform more delicate movements.
Tendons are mostly collagen, one of the most abundant proteins in the body. Tendons also contain blood vessels and nerves. Apart from collagen bundles, there are matrix proteins which mostly retain water and provide elasticity. Collagen fibres are flexible, strong, and relatively resistant to damage. A tendon’s structure is similar to a fibreoptic cable or a rope, with small collagen fibres arranged in bundles. This bundling supports the tendon and makes it stronger.
The collagen fibres in a tendon group into:
- Primary fibre bundles, the smallest bundle.
- Secondary fibre bundles made of groups of primary fibre bundles.
- Tertiary (third) fibre bundles containing groups of secondary fibre bundles that form the tendon itself.
A tendon consists of:
- Endotenon: Connective tissue that surrounds the primary, secondary, and tertiary fibre bundles, like socks. Helps the bundles glide against each other inside the tendon.
- Epitenon: Thin layer of connective tissue that surrounds the entire tendon.
- Paratenon: Loose layer of connective tissue that lets the tendon move against the epitenon and other tissues that the tendon touches. Located outside the epitenon.
- Sharpey fibres: Collagen fibres that attach the tendon to the bone.
- Sheath (synovium): Some tendons in the hand and foot have a sheath (synovium). This is the protective outer covering of the tendon. Produces a lubricating fluid called synovial fluid, which helps the tendon slide smoothly where it meets muscle and bone.
Tendons connect the muscles to the bones at the following points:
- Musculotendinous junction (MTJ): The point where the tendon attaches to the muscle. This is the site where injury or degeneration occurs more frequently.
- Osteotendinous junction (OTJ): The point where the tendon attaches to the bone.
The Sharpey fibres that are part of the tendon extend into the bone. The tendon of the hand and foot commonly slides through a connection called a reflection pulley that helps hold it in place. Small, fluid-filled pads called tendon bursae cushion tendons where they meet the bone.
