joint

a connections between BONES (and CARTILAGES ). Joints can be categorized by their structure and the degree to which they permit movement: fibrous joints are fixed by fibrous tissue binding bones together, e.g. the bones of the skull. cartilaginous joints are slightly movable. These have discs of cartilage between bones so that only limited movement is permitted over one joint but over several adjacent joints considerable flexure is achieved, as with the spine. synovial joints can move freely. Each synovial joint comprises the bones. cartilage over the ends, then a capsule (sheath of fibrous tissue) from which the ligaments form, and a SYNOVIAL MEMBRANE containing synovia for lubrication. This type of joint then occurs in two forms: hinge joints allowing planar movement (e.g. the knee), and ball and socket joints permitting all-round movement (e.g. the hip). Joints are subject to various conditions and diseases, including SYNOVITIS , epiphysitis (inflammation of the EPIPHYSIS ), GOUT , RHEUMATISM and dislocations.