Fingerprints are unique patterns found on our fingertips, formed by raised friction ridges and recessed furrows. These intricate designs develop during fetal growth and remain unchanged throughout a person’s life. While no two fingerprints are identical, even among identical twins, they can be broadly categorized into three main pattern types: loops, whorls, and arches. Among these, loop patterns are the most commonly observed.
Characteristics of Loop Patterns
Loop patterns are characterized by ridges that enter from one side of the print, recurve, and then exit on the same side. Within the pattern area of a loop, two focal points are used for classification: the delta and the core. The delta is a triangular-shaped area where ridge lines diverge. The core represents the innermost turning point of the loop, the approximate center of the fingerprint impression. Loops possess one delta and one core.
Features of Ulnar Loops
Ulnar loops are a type of loop pattern where ridges flow towards the little finger side of the hand from which the print was taken. This directionality is named after the ulna bone, located on the pinky side of the forearm. The loop’s opening faces the ulna bone. Ulnar loops are the most prevalent fingerprint pattern, accounting for approximately 60% of all patterns. Some studies indicate they are more common in females.
Features of Radial Loops
In contrast, radial loops exhibit ridges that flow towards the thumb side of the hand from which the print originates. This orientation is named after the radius bone, which connects the forearm to the hand on the thumb side. The loop’s opening points towards the thumb. Radial loops are less common than ulnar loops, often found more frequently on the index finger. Some research suggests radial loops may be more common in males.
The Core Distinction
Distinguishing an ulnar loop from a radial loop depends on the direction the loop’s ridges flow relative to the hand’s anatomy. One must first determine whether the fingerprint originated from the left or right hand. Once the hand is identified, observe the direction in which the loop’s opening points. If the ridges of the loop flow towards the little finger (pinky) of that specific hand, it is classified as an ulnar loop; conversely, if they flow towards the thumb, it is a radial loop. For example, a loop on a right hand that opens to the left (towards the thumb) is a radial loop, while a loop on the same right hand that opens to the right (towards the pinky) is an ulnar loop.