The answer to Thursday riddle poem #19

SrOhZ
Tunnel of Love in Ukraine via blog.freepeople.com

Thursday riddle poem #19
By Annette Marie Hyder

I can Spock
a brow;
reverse ride the horns of any cow.
I can raise a cat’s back like a bridge;
make a perfect tunnel
in the middle of your feet.
I’m a basic fingerprint motif
and you inverse me when you smile
at someone you’re pleased to meet.

What am I?

An arch