May include injuries to the anterior cruciate ligament and collateral ligaments. Muscle, cartilage, nerves, bursae, ligaments and tendons may be damaged from overuse. The anterior cruciate ligament is one of the four crucial ligaments in the knee. The anterior ligament is thin and not as well defined as the posterior sacroiliac ligaments. 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. Tendons are similar to ligaments; both are made of collagen. Golgi tendon organs function as static mechanoreceptors for protection of ligaments around the temporomandibular joint. The coccyx serves as an attachment site for tendons, ligaments, and muscles. Both cruciate ligaments are slightly unwinded and both lateral ligaments become taut. Race horses are especially prone to injuries of the tendon and ligaments. Ankle sprains occur usually through excessive stress on the ligaments of the ankle. The knee is stabilized by a pair of cruciate ligaments. The pelvis, associated ligaments and muscles provide a floor for the pelvic structures.