Why the wedding ring is worn on the fourth finger?

Interesting concept.

That is a good question, but having the fingers positioned in that manner is essential for the validation of the theory that is put forth here. Though the tendons in your fingers are independent from one another, but the ring finger are not and its the weakest finger. Since these tendons are connected, it shares muscles with the middle and the pinkie. Therefore, it cannot extend fully by itself, making it feel as if it were stuck!