Tendon Structure

Schematic presentation of tendons and ligaments structures.

Left, Lateral view of the human knee joint, including tendons and ligaments.

Right, Structure of tendon and ligament fibers. Collagen fiber, comprised of collagen fibrils, is the basic unit of tendon.  A group of collagen fibers forms a subfascicle, which, in turn, clusters to form fascicle. Fascicles group into tertiary collagen bundles, which finally form the tendon. Endotenon, a thin connective tissue, envelops each fiber. Epitenon wraps the final tendon unit.