As mentioned in previous entries, the most common word for arm/hand in Russian is рука. What if you want to be more specific?

First off, the actual hand is called кисть, which is a feminine noun. It includes запястье the wrist, пястье (the area from the wrist to the first knuckle of each finger, which is also called пясть... heck, do we even have a word for that in English?), and пальцы “the digits.” I say “digits” here because the word палец can mean either finger or toe. If you want to specify fingers, then you say пальцы рук, and if you want to specify the toes, you say пальцы ног.

Next we have the forearm предплечье, in which the major bones are the radius лучевая кость (literally “the ray bone”), which is the bone on the same side of the arm as the thumb, and the ulna локтевая кость (literally “the elbow bone”). I think the average American doesn't know the words radius and ulna. The Russian phrases are a bit more descriptive than the Latinate English equivalents. I wonder if the average Russian knows the names of those bones in Russian? Maybe we'll be fortunate and a native will add a comment about that to this post.

Moving on up we have the elbow локоть, a masculine word, whose second о is a fleeting vowel, thus genitive локтя.

Moving farther up we have плечо, which can mean either the shoulder itself, or it can mean collectively both the shoulder and the upper arm. The bone in the upper arm is плечевая кость, literally “the shoulder bone.” That sounds funny to us Americans. Although the proper name of the bone is “the humerus,” there is a song called “Dry Bones” that contains a line “the arm bone's connected to the shoulder bone;” it sounds amusingly folksy. Even humorous… pun intended.

Last but not least, the English word palm means the front side of what the Russians call пястье. Isn't that curious? We have a word in English that describes the area from the wrist to the first knuckles of the fingers as understood from the front side of the hand, but we don't have a word that describes it from the back side. The Russian word for palm is ладонь, which is a feminine noun. Isn't that curious? Both languages have a word for that part of the hand as considered from the front side. Russian has two words (пястье & пясть) for that part of the hand as considered from either side, but English has no such word. And both languages (as far as I know, correct me if I'm wrong) do not have a single word describing that part of the hand as considered solely from the back side.

Finally, Russian has a conversational term they use sometimes, пятерня, which means “the palm and the fingers,” i.e. what we English speakers usually call the hand, but пятерня is used much, much less often than рука.