The morphology of the components of the knee joint is reviewed, with particular reference to the ever-widening range of technical representation offered by modern imaging procedures. The morphological parameters of cartilage thickness, thickness of the subchondral zone of mineralization and subchondral X-ray density (assessed by CT osteoabsorptiometry) are depicted, and the various parts of the capsular ligamentous apparatus are described, with particular attention to the cruciate ligaments and menisci. The periarticular topography is also dealt with briefly. An attempt is made to elucidate with diagrams the essential basis of the static stress acting on the joint. The kinematics and dynamics are examined with particular reference to new theories about control of the position of the joint as a result of sensory functioning of the cruciate ligaments.