Answer: Hi! The answer you're looking for is:
"The nerve that is connected to skin receives stimuli information from the external environment; the nerve that is connected to a muscle receives processed stimuli information from the brain."
When you receive, for example, a touch on your arm, the nerves connected to your skin transfer the information of this touch to your brain - in other words, it tells you how it felt. This touch would obviously be external, or outside of your body. Nerves connected to your muscles transfer information like how your muscles feel after hard exercise, or directions from your brain on how to move a muscle - I'm using my arm muscles and my finger muscles right now to type this answer for you! This would be internal.