Tendons are cords of connective tissue attaching muscle to bone, cartilage or other tendons. Bones are connected to muscles via tendons and other bones via ligaments. Muscle, cartilage, nerves, bursae, ligaments and tendons may be damaged from overuse. Other problems include premature epiphyseal closure and calcification of tendons and ligaments. Enthesitis is tenderness at the insertion sites of tendons, ligaments and fascia caused by inflammation. It is mostly found in fibrous tissues such as tendons, ligaments, and skin. The coccyx serves as an attachment site for tendons, ligaments, and muscles. Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons. Muscles are bundles of contractile fibers that are attached to bones by tendons. It develops the forearm muscles along with the tendons and pulleys of the fingers. Other important uses include imaging the abdominal organs, heart, breast, muscles, tendons, arteries and veins. The lumbricals attach in part to the flexor digitorum profundus tendons. Proprioception is mediated by proprioceptors, mechanosensory neurons located within muscles, tendons, and joints. It also provides an attachment for muscles and tendons. The compartments are numbered with each compartment containing specific extensor tendons.