It looks crooked and sticks out from all the other fingers on your hand. To check, try to bend and get your 'crooked' finger to touch the palm of your hand. If it hurts, its broken
If you have broken a metacarpal your finger will still look fine as the metacarpal is the finger bone inside your hand, metacarpal breaks are usually caused by punching something and your hand will swell and be painful.
So the the metacarpal is the long bones inside your hand that directly connect to your finger (if you look at a skeleton, you would say it was a finger) I know what and where it is because I broke mine!! and certainly not the wrist!!!
Metacarpal as in matatarsal - carpel is to wrist as tarsus is to ankle... long bone originating from said areas. Smaller bones ie. fingers and toes are made up of phalanges. If you broke a metacarpel it would relate to a long bone in the hand, not a finger.
I didn't say it was a wrist... pr*@k. The long bone - metacarpal - in your hand is not your finger, like a metatarsal isn't your toe. I happen to deal with these things for a living so I'm not pedantic, just right.