Like climbing into your own vehicle; you know which creaks, groans and sensations are normal and which spell potential trouble. You might even think or feel that it is part of you, but it is certainly not 'you'. Same principle.
This set me to thinking, how do we actually define our body? Is it everything we can feel on the inside with touch? It certainly isn’t everything we can feel on the outside, or we can see, or hear.
If you’ve ever had the experience of ‘inner seeing’ in meditation, as if you were seeing inside your body, then this might call up some feelings of confusion. Or if you’ve felt sensation of things that weren’t actually there, like a touch in an area outside your body.