Involucrum
Template:Distinguish An involucrum (plural involucra) is a layer of new bone growth outside existing bone.
There are two main contexts:
- In pyogenic osteomyelitis where it is a layer of living bone that has formed around dead bone.<ref>Template:Cite journal</ref> It can be identified by radiographically (i.e., with x-rays).
- In cetaceans such as whales, it is a thick covering of bone over the middle-ear space.<ref>Template:Cite web</ref><ref>Template:Cite journal</ref>