The skin is not scraped if layers of the skin are sliced.
Puncture - a wound usually caused by something sharp and pointed. The opening of the skin is small and the wound does not bleed much. So it's not a puncture.
Laceration - a wound produced by the tearing of body tissue, as distinguished by a cut.
Since the knife cut through layers of the skin which includes the tissue underneath, the injury is a laceration.
