While "Srednyaya Protoka" means the "Middle Arm", the names of the main western and eastern arms indicate their relative location as well. The "Kolymskaya Protoka", or "Kolymskoye Ustye" is the arm one located on the eastern side, i.e. the "Kolyma side" of the delta (the arm closest to the Kolyma, the eastern neighbor of the Indigirka). The "Russko-Ustyinskaya Protoka", apparently known earlier as simply "Russkoye Ustye" is the arm one located on the western side, i.e. the "Russian side" of the delta (meaning, the side closest to the (European) Russia). These days the name of the "Russko-Ustyinskaya Protoka" appears as if it were formed from the name of the old Russian village Russkoye Ustye situated there, but originally the opposite is likely to have been the case, the village is named after the river arm (the "Russkoye Ustye") on which it was located.