The marrow is one of the three layers in a living bone. If we cut though the compact bone, we find that its cylinder surrounds and protects the spongy bone marrow, which contains a material, much like gelatin. This cylinder is the medullary cavity, and is the central cavity of bone shafts. It is where yellow bone marrow (or adipose) is produced and stored, and also where we find red marrow. In infants, Continue Scrolling To Read More Below...