Shape Variations in Loop Pattern Fingerprints: Radial vs. Ulnar Loops

Research Article

Austin J Forensic Sci Criminol. 2015;2(1): 1013.

Shape Variations in Loop Pattern Fingerprints: Radial vs. Ulnar Loops

Králík M*, Kováčová V, Hupková A and Urbanová P

Department of Anthropology, Masaryk University, Czech Republic

*Corresponding author: Králík M, Department of Anthropology, Laboratory of Morphology and Forensic Anthropology (LaMorFA), Masaryk University, Kotlárská 267/2, 611 37, Brno, Czech Republic

Received: October 21, 2014; Accepted: January 02, 2015; Published: February 16, 2015


Loops are very common categories of fingerprint patterns found on terminal phalanges of the human hand. Their assessment is paramount in the process of police fingerprint identification. A detailed classification system capable of distinguishing between radial and ulnar loops, loops of right and left hand, or those of thumb and other fingers would largely benefit to cases where only a single loop is secured at crime scene. The aim of our pilot study was to assess differences in size and shape of radial and ulnar loops. We explored morphological variations in the sample of 489 loop ink fingerprints using 20 distance measurements and indices and Fourier shape analysis. Our results show that there are systematic size and shape differences between radial and ulnar loops on index fingers, primarily concentrated in the course of the distal type line. If developed further the proposed methodology, particularly if directed at advanced methods of geometric morphometrics, may find practical usage in differentiating fingerprint patterns in police/forensic fingerprint investigation.

Keywords: Fingerprint patterns; Ulnar loop; Radial loop; Radio-ulnar asymmetry; Shape variations; Fourier analysis


Fingerprint patterns called loops (simple loops) characterized by one triradius (or delta) and one core are very common in most of the human populations. Moreover, for some human groups they represent the most frequent patterns of fingers´ terminal phalanges [1,2]. Based on their orientation towards axis of distal phalanx or according to the direction of the cauda of the pattern (Figure 1), two principally opposite categories of loops can be distinguished. In ulnar loops cauda is directed towards the ulnar side of the finger (the little finger), whereas in radial loops cauda is directed towards the radial side of the finger (the thumb).