The Core Distinction: Connecting Muscles vs. Bones
The primary difference between tendons and ligaments is what they connect within the body's musculoskeletal system. Tendons are tough, flexible cords of fibrous tissue that connect muscles to bones. In contrast, ligaments are also fibrous connective tissues, but their function is to connect bones to other bones, primarily to stabilize joints.
Section 2: Composition and Structure
Both tendons and ligaments are composed mainly of collagen, but their fiber arrangement differs based on their function. Tendons feature densely packed, parallel collagen fibers that give them high tensile strength to effectively transmit the force generated by muscle contractions. Ligaments have their collagen fibers arranged in a more interwoven, crisscross pattern, which allows them to resist forces from multiple directions and maintain joint stability.
Section 3: A Practical Example
A classic example of a tendon is the Achilles tendon, which connects the calf muscles to the heel bone, enabling you to stand on your toes. A well-known ligament is the anterior cruciate ligament (ACL) in the knee. It connects the thigh bone (femur) to the shin bone (tibia), preventing the shin bone from sliding forward and providing rotational stability to the knee.
Section 4: Importance in Injury
This distinction is critical in medicine. An injury to a tendon is called a 'strain,' which typically occurs from overstretching or tearing due to muscle overload. An injury to a ligament is known as a 'sprain,' which happens when a joint is twisted or forced beyond its normal range of motion. Because both have a limited blood supply, healing can be a slow process.