Alan Vanneman offers some insight into Hitchcock with a focus on hands. "In the Jesuit school that Hitchcock attended as a boy, misbehavior was punished by blows to the hand with a sort of rubber truncheon or club. I suspect that this experience helped Hitchcock to think of hands as the symbol of human vulnerability. In his films, people are always extending their hands in hope of assistance, and very seldom getting it." (Bright Lights Film Journal) Thanks to Relapsed Catholic for the link.