Joint cavity shared by all the joints of the elbow. The elbow joint is a compound joint that actually comprises three separate joints: the joints connecting the upper and lower arm: 1) Articulatio humero-ulnaris and 2) Articulatio humero-radialis as well as the proximal joint connecting the forarm bones: 3) Articulatio radio-ulnaris proximalis. All three share a joint cavity which is highly sinuated/scalloped/coved. Joint spaces of the elbow summarizes the joint cavity shared by all three adjoining joints of the elbow joint. [ HP:0003943 ]