Why does having anesthesia make my lip feel swollen?

[harryrooster]

I went to the dentist the other day and got a shot of Lidocaine (an Inferior Alveolar Nerve Block according to what my research told me), and it worked great, the whole side of my lip and part of my tongue were numb, just as expected. I was curious however as to why I was still able to feel pushing and why my lip felt like it is swollen when it clearly is not. My research got me as far as stating that the nerves supplying the lip are the facial nerve and the trigeminal nerve. The shot numbs that portion of the trigeminal nerve, which is only supplying sensory to that area, the facial nerve is supplying motor to that area, which explains why I can still move my lip. But why do I still feel pushing and like my lip is swollen? I couldn't find anything stating that the facial nerve minor sensory abilities, and according to what I read, there is no other nerves in the lip (with exception to nerves that are branches of the trigeminal or facial nerve - eg. mental nerve).

Thanks in advance,

Harry

 

[Gordon]

Local anaesthetic doesn't block out all nerve transmission, just painful ones. It's almost like a very strong painkiller, applied locally, hence you can still feel pressure, hot, cold etc. I don't think anyone knows how this works, but anaesthetics in general are quite poorly understood.

As for why your brain interprets this as feeling swollen, nobody has a clue here either.