Actually, it was before anyone in the US talked about karate, in the
50's or 60's when one would often see someone knock another
unconscious by hitting him at the base of the skull, neck, somewhere.

A well timed well placed elbow strike will incapacitate almost anyone. It
is delivered by the elbow, and with the fist being held close to the chest
by the other hand. The shoulders and torso is rotated rapidly putting a lot
of mass behind the elbow which is solidly connected and supported. A good
blow can literally knock someone off their feet so that they land on their
head or shoulders. Looks like someone getting clotheslined at a full run.
When applied to the sternum, they can be fatal. Head blows have been fatal.
It is a devastating blow in close fighting, and one that 99.9% of opponents
never see coming. It is so bad that it is rarely used in UFC because it is
so lethal when done right.

Steve