The laan sao will be described as locking arm. It is used to free some space from the opponent in front of the body, to build up space in which...
encyclopaedie
Wu sao will be described as protecting hand. It is the last line of defense in front of the body, before the attack reaches it.
What we describe as jum sao is the sinking elbow. This minimal move protects the under part of the upper body like belly and liver.
The jut sao is executed with the inner part of the wrist and serves as a preparation for further attacks like a punch or a fung hao.