Koko uchi (literally: “tiger’s mouth strike”) earns it name because the hand resembles a hungry jaw. Cats, such as tigers, suffocate their prey by crushing their breathing passages, resulting in suffocation.
[photo of a koko from the front and side and top]
The setup to wristlocks can also be imagined as a koko uchi to the wrist.
[Koko uchi fast and slow, from the front ans side several times.]