This one is going to be rather less sciency, if you like your science to evidence-based and peer-reviewed (don't we all?!). That's because I'm going to attempt to explain something that I don't believe to be fully explicable. Good luck!
The main metaphor I want to use is this: that, for me, feeling things in my body in general and legs in particular, is like listening to the outside world when you're also listening to music on headphones.
As soon as you put on a pair of headphones and start listening to music through them, almost everything that you can hear is what is in your headphones. You can't hear the outside world very well because your hearing is overwhelmed by the sound coming out of the headphones. It's not that you've lost your sense of hearing - after all, you're hearing your music just fine - but nothing from outside can really get through until you take those headphones off.
|This is how it feels - the headphones don't just go in the ears; they pump the feeling all over!|
The way that I feel my legs is very like this, but there is one subtle but important difference. In the headphones example, the sounds you are hearing still come from outside yourself; outside your head. They're being piped straight into your ears and you might feel really immersed in the music but ultimately the sound is still external.
I suppose a refinement of the headphones analogy would be to say that you have something going in your head which you can hear so vividly that it completely distracts you from being able to hear anything else. I went with headphones because that's an easier one for most people to try out or understand, but the music in your head is a better fit for mapping onto me and my legs.