A knifehand strike is a strike using the part of the hand opposite the thumb (from the little finger to the wrist), familiar to many people as a karate chop, (in Japanese, shutō-uchi). This refers to strikes performed with the side of the knuckle of the small finger down the forearm to the elbow. Suitable targets for the knife hand strike include the mastoid muscles of the neck, the jugular, the throat, the collar bones, the 3rd vertebra (key stone of the spinal column), the upper arm, the wrist (knife hand block), the elbow (outside knife hand block), and the knee cap (leg throw).
Japanese martial arts
In many Japanese and Chinese martial arts systems, the knifehand is used to block as well as to strike. In Tae kwon Do a knifehand strike (sonkal taerigi) is executed by striking with the muscle at the side of the hand located between the base of the small finger and the wrist (abductor digiti minimumi). It is used as both an offensive and defensive technique and can be executed as a high, low, middle, side, inward, outward, rising or circular strike.
The popularity of martial arts in mid to late 20th century gave rise to an exaggerated version of a knifehand strike widely used in American and British cinema, television, and animated cartoons. In common depictions, a character will deliver a single, precise-looking but relatively weak strike to the side of an opponent’s neck, which instantly renders them unconscious but otherwise unharmed (in some versions, the blow is instantly fatal). This is frequently done from behind to an unaware adversary, often an enemy guard. The move became a staple of the spy genre through the 60s and 70s.
As audiences became more aware of how implausible this move seemed, it gradually migrated to the realm of comedy. In these depictions, it is either used unexpectedly and found to work in absurd situations, or a character attempts to imitate what they saw in film, only to find it has no effect.
The following video shows Iain Abernethy demonstrating a practical drill for the use of Shuto-Uke (“knife hand block”) and Nukite (spear hand) that is infinitely more applicable than the ‘judo chop’ of the movies.