Names are not THAT important but its nice to know the major ones for reference. There are a few unnamed, and a lot of minors that are not drawn out specifically, most of which you won't need for drawing most of the time.
Theres not much dynamics explained here besides the simple flex and stretch, but knowing the placement of major muscle really defines the shape of the arm realistically, its good even if you draw anime style.
the muscles are not held in place to each other by superglue, so as you turn your arm the muscles slide over each other, only the tendons joint to the bones are stationary.
Remember which one is on top and which one crosses over which muscle and where their tendons join to bones then you will be able to construct how they will move with your imagination.
Muscles retains relatively similar in volume despite how they stretch, so if its made shorter by some movement, then it will appear fatter, and if its stretched (like by a twist of arm) then it will appear thinner.
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EDIT__ I noticed I misspelled Bicep* I am not going to go back and change all the 'bicept' just because its too tedious lol.
If you compare joint to joint its pretty much the same, but if you compare wrist to top of the shoulder the upper will be longer just because you are including the collar bone on top of the joint. Not by a significant amount, and I am sure it could vary in people enough so that it might as well be the same.