Does a full hand need to be washed for mayim ahcaronim, or just the knuckles–even according to the Gra?
Answer:
It appears that according to the Vilna Gaon, the entire hand needs to be washed for mayim acharonim. According to other poskim there is no need to wash beyond the knuckles.
Sources: See Orach Chaim 181:4, Biur Ha-Gra, and Biur Halachah. Damesek Eliezer (161:1) explains that according to the Gaon (based on Rif) there is no difference between mayim rishonim and mayim acharonim.
