The musculoskeletal system provides form, stability, and movement to the human body. It consists of the body's bones (which make up the skeleton), muscles, tendons, ligaments, joints, cartilage, and other connective tissue. The term "connective tissue" is used to describe the tissue that supports and binds tissues and organs together. Its chief components are collagen and elastic fibers, which are composed of different proteins.
The musculoskeletal system comprises bones, muscles, joints, ligaments, tendons, and bursae (see Introduction to Biology of the Musculoskeletal System). Any of these components can be injured or affected by a number of disorders.
In an autoimmune disorder, antibodies or cells produced by the body attack the body’s own tissues. Many autoimmune disorders affect connective tissue and a variety of organs. Connective tissue is the structural tissue that gives strength to joints, tendons, ligaments, and blood vessels.
Gout is a disorder in which deposits of uric acid crystals accumulate in the joints because of high blood levels of uric acid (hyperuricemia). The accumulations of crystals cause flare-ups (attacks) of painful inflammation in and around joints.
Neurogenic arthropathy is caused by progressive joint destruction, often very rapid, that develops because people cannot sense pain, continually injure joints, and thus are not aware of the early signs of joint damage.
The muscles, bursae, tendons, and bones must be healthy and functioning correctly for the body to move normally. Muscles, which contract to produce movement, are connected to the bones by tendons. Bursae are flat sacs containing joint (synovial) fluid. They reduce friction in areas where skin, muscles, tendons, and ligaments rub over bones. (See also Biology of the Musculoskeletal System.)