You've heard all the expressions. Swing a leg over. Throwing an arm out. Dropping your jaw. Keeping an eye out. And there are many more. It's important to watch for these expressions. We use them all the time in our speech, but they don't belong in descriptions, though it's entirely possible most of your readers won't notice a thing.
Consider carefully the motion possibilities of the different body parts. While body movement is very useful in showing action as well as attitude, making the body accomplish outlandish feats is something to use with extreme caution.
The legs can do quite a bit. They perform walking, kicking of objects, and an assortment of stands that can indicate attitude. When mounting a horse, it's quite common to 'swing your leg over the saddle'. This is probably the worst example I could come up with, especially if you read westerns or were brought up around horses (or both), but it still illustrates my point. Taken alone, it sounds like this guy had a prosthetic leg and he just detached it in order to hang it over on the other side of the saddle somehow.
Arms are much the same. Very useful as far as body movement. In fact, arms and hands are always in motion unless the hands are tied behind the back. In fact some people might find it difficult to make a point if their hands are bound - possibly - depends on how dependent they are in the use of their hands during talking. Hands are almost always in motion, but you can't 'throw them out'. I see this rather frequently when someone is talking about directing traffic or signaling a turn. There's also 'throwing a punch' to carefully consider.
Every hear this one? "His jaw dropped" You're better off using something like, 'He was gape-mouthed' or something similar. In the interest of future dialogue, it's best to keep the jaw attached to the skull.
Now eyes are probably the easiest to misuse. 'Keep an eye on, or out for, someone or something' may well be the biggest example. 'Rolling eyes' is another, after a fashion. Eyes are very talented; in fact, I like to call them the window into the soul. They are full of expression, but they can't go anywhere on their own. I'm sure you all can come up with many examples of your own. If fact, I would appreciate it if you would post your examples, and possible alternatives, for all of us to share.