Name___________________________________________________Core____________
FINGERPRINTS
CLASSIFICATION OF FINGERPRINTS
Highly variable fingerprint patterns can be classified into three major groups –
arches, loops, and whorls – according to the pattern of dermal ridges.
Arch – The arch is the most simple and least frequent pattern. The arch may be
subclassified as plain when the ridges rise slightly over the middle of the finger or tented
when the ridges rise to a point.
Plain Arch
Tented Arch
Loop – The loop pattern has a triradius and core. A triradius is a point where three
groups of ridges form in three directions at angles of about 120 degrees. The core is
essentially a ridge which is surrounded by fields of ridges which turn back on themselves
at 180 degrees. Loops can be either radial or ulnar. A finger possesses a radial loop if
its triradius is on the side of the little finger for that hand and the core points toward the
thumb. A finger has an ulnar loop if its triradius is on the side of the thumb for that hand
and the core opens toward the little finger.
Whorl – The whorl has two triradii (plural of triradius) with the ridges forming various
patterns inside.
Name___________________________________________________Core____________
Frequencies of these finger pattern types in the general population are as follows
(Holt 1968):
Arch = 5.0%
Ulnar Loop = 53.5%
Radial Loop = 5.4%
Whorl = 26.1%
RIDGE COUNT
Our focus for this investigation is a quantitative trait called the total ridge count.
The ridge count on a finger is determined by counting the number of ridges between the
triradius and the center (core) of the pattern. In an arch, the ridge count is 0. In a whorl,
only the higher of the two possible counts is used (see the figure below).
(a)
Arch
No triradius
(b)
Loop
One triradius
(c)
Whorl
Two triradii
(a) Ridge count is 0.
(b) Ridge count is approximately 15.
(c) Ridge count is approximately 15 (the higher of the two counts).
The total ridge count (TRC) is the sum of the ridge counts of all ten fingers. The
average TRC for males is 145, and for females it is 126 (Holt 1968).
INHERITANCE OF FINGERPRINTS
Are fingerprints inherited? Are they more similar between family members than
between strangers?
The general shape or overall pattern of finger and palm prints can be inherited. Family
members will often have similar patterns or designs (whorls, loops, etc.) on the same
fingers of their hands. However, the tiny details in the fingerprint ridges are not inherited
and are different between all friction skin areas of all persons... even between twins.