Origin of the term 'mouse' to describe injury to face/eye?

Watching UFC (and maybe boxing too, I don’t as I don’t watch boxing), you often hear it mentioned when a fighter gets a punch to the face and subsequent swelling under his eye that ‘he’s got a mouse under his eye’, for example. Where does the use of the word ‘mouse’ to describe this injury come from?

It, of course, derives from the animal. The OED has a first cite of 1842:

It’s not clear how the word developed the meaning, though this definition is interesting:

It’s possible that the swelling was considered similar to the rope around the nautical eye. First cite predates (it’s from 1750) that of an injury.

I was taught in Latin class that the term in latin for Mouse is “mus” and that’s been used a reasoning for the derivation of the term “muscles” as basically being the “little mice” that run under your arms.

So mice and the human body have been used together for a while for sure. Just another interesting linkage of the two.

Because it looks like a mouse? A small, roundish, dark swelling?

You can hear the term a lot in old time radio (OTR). You usually have a joke along the lines like “Wow that rat really gave you a mouse.”

Looks more like a slug to me.

Thanks for the replies folks.