Question about nursing & patient abuse

I am not a nurse, I am a CNA. I am interested in a career working with elderly, possibly as a nurse later on. I have not yet worked in healthcare, I am still in the process of obtaining employment.

I am concerned about having to answer for injuries or bruises incurred by a patient or resident that I don't cause, but that happen anyway (for unknown reasons). How often does this happen? And how do you protect yourself? I don't want to be falsely accused of abuse.

The elderly tend to bruise easily- you can protect yourself by documenting any injuries that occur, and by documenting bruises as you notice them.