A
spatium or
anatomic space is a space (cavity or gap) in
anatomy. Anatomic spaces are often landmarks to find other important structures. When they fill with gases (such as air) or liquids (such as blood) in pathological ways, they can suffer conditions such as
pneumothorax,
edema, or
pericardial effusion. Many anatomic spaces are
potential spaces, which means that they are potential rather than realized (with their realization being dynamic according to
physiologic or
pathophysiologic events). In other words, they are like an empty plastic bag that has not been opened (two walls collapsed against each other; no interior
volume until opened) or a balloon that has not been inflated.