In Dead 7, Carrie and other movies, there have been some scenes where an artery has been severed and an open wound is visible causing an artierial spray coming from inside the wound.
I am sure this may be CGI or whatever, and for the wound, I have no idea, but there doesn't seem to be any fake blood tubes coming from the area of the spray.
The blood just squirts and squirts. In Dead y, Apocalypta slits a mans throat when he wants to join her and it results in arterial spray.
Also in an episode of The walking dead where the cannibals have got hold of some survivors, they slit the survivors throats over a trough, resulting in arterial spray.
How is this filmed?