Radial loop

Radial loop is a term used in classifying fingerprints. Radial loops start on the thumb-side of the finger, the side closer to the radius (bone).The distinction between Ulnar and Radial loops depends on which hand the loop is found on. In the image at left the core pattern area (noted in red) tends to come in from the left and go back out the left. Hold your left hand up to the screen and note that your little finger is on the left, which is the direction that the pattern tends to come in from and go back out to. Since this is towards your little finger, and by virtue of that towards your Ulnar bone in your arm, this makes the loop an Ulnar loop.

Now, if you were to place your right hand up to the screen and make the same comparison you would find that the pattern area now tends to come in and go out towards your thumb. It so happens that the radial bone in your arm is on your thumb side so now this loop would be considered a radial loop.Obviously to make the distinction between these two types of loops you have to know on which hand they appear because if a loop pattern is an Ulnar loop on the right hand, then by default it will be a Radial loop if found on the left hand.Radial loops are not very common. Most of the time if you find a radial loop on a person it will usually be on the index fingers.