How do undermining and tunneling differ in regards to stage 4 pressure ulcers?

Undermining: Undermining occurs beneath the skin surface in continuation with the ulcer. Tunneling can occur in a deeper plane f the wound base.

Different etiologies: Our skin is made to take direct pressure, the deep tissues are not. When pressure is applied, it spreads out and depending on the direction "kills" the tissues under the skin causing undermining. A tunnel occurs when there is lateral force to the deep tissues disrupting the tissue planes in the direction of that force creating a "tunnel". Treatment is the same...Stay off it !

Semantics: The process is the same for both, pressure damageto softer tissue underlying the comparatively tough skin. Undermining leaves a shelf of skin over a cavity while tunneling is a relatively straight line as its name would suggest covering possibly a great distance under the skin.