Coloured scanning electron micrograph (SEM) of tendons and other connective tissue attached to a bone surface. Tendons are fibrous connective tissue that is usually collagen based. A tendon is composed of thick, closely packed bundles of collagen fibrils oriented parallel to the long axis of the tendon. Tendons attach muscles to internal structures such as bones or other muscles. Sometimes when the muscle involved is thin and wide, the tendon is not a cord but a thin sheet known as an aponeurosis. Tendons attach muscle to bone to enable the power of the muscle to transfer over a distance. Magnification: x200 when shortest axis printed at 25 millimetres.