Is there a medical or otherwise obscure word which means “corner of the mouth”? Need it for something I’m writing. Thanks!
We would say ‘angle of the mouth’. Although there may be a latin anatomical name as well, I can’t remember it.
commissure
Sounds like someone is writing erotica. 
I’ve never heard any other word or phrase for it.
I was thinking odontological poetry, but I guess erotica is also a possibility. I am sure there are plenty of good rhymes to commissure.
Commissure.
Also works for corner of they eye. Usually specify which one, ie. Left or right commissure of the mouth, lateral or medial commissure of the left or right eye.
Haha…a romantic comedy, actually. And one of my main character’s quirks is he’s constantly using ten-dollar words. I think commissure will do. Thanks!
If you’re talking of the muscular anatomy of the face, the Modiolus is the fibrous attachment area for many of the muscles that attach to the corner of the mouth.