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Why Do We Have Fingerprints?

Dermal Papillae: an undulating sub-layer that causes friction ridges

Why Do We Have Fingerprints?

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Friction Ridges allow us to hold on

to things more easily.

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Fundamental Principlesof Fingerprints

They don’t change.

Can be classified by their ridge patterns

Unique because of minutiae

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3 Types of Ridge Patterns

o Loops•Whorls•Arches

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Loop

one or more ridge enters and exits from the same side. Loops must have one delta (triangular area).

Types Radial: opens toward the thumb Ulnar: opens toward the “pinky”

(little finger)

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Whorl

at least one ridge makes a complete circuit.

Types Plain Central Pocket Double Loop Accidental

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Arch

has ridges that enter on one side, rises in the middle, and ends on the other side

Types Plain Tented

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3 Types of Ridge Patterns

o Loops: most common pattern (65% of people have these)

• Whorls: 30%• Arches: least common pattern (5%)

Individual fingers can have different ridge patterns!

Galton: observer of minutiae

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Minutia: small patterns in the print

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Examples of Minutia

RIDGE ENDINGBIFURCATION

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More Minutia Examples

SHORT RIDGEISLAND

ENCLOSURE