Minutiae

Origin of Fingerprints Purpose of friction ridges – to provide a textured surface for gripping and holding on to objects Friction ridges arise from the dermal papillae layer of the skin. Ridges start to form at the 8th week of gestation and are done by the 17th week of gestation From that point on, fingerprints never change; they only grow larger as the body grows

Origin of Fingerprints

The Origins of Fingerprints Sweat glands form in the dermis and terminate as sweat pores on the ridges Perspiration is discharged from the sweat glands and exits through the pores onto the surface of the ridges Perspiration along with sweat, skin cells, proteins, fats, and other materials are deposited when a finger touches a surface. These invisible fingerprints are called latent prints.

Three types of Fingerprints Latent prints – a fingerprint that is not visible to the unaided eye Patent prints – a visible fingerprint deposited via a substrate such as blood, grease, or paint Plastic prints – a visible fingerprint impression deposited by contact with a soft material such as putty

Patent and Plastic Prints

Origin of Sweat Glands

The Anatomy of Fingerprints A fingerprint consists of the friction ridge skin of the last joint on each finger taken from cuticle to cuticle Major ridge shapes: Ending Ridges Bifurcations (also known as a fork) Trifurcations Dots (also known as a very short ridge) Island ridges (also known as a short ridge) Enclosures (also known as an eye or island) Bridge (also known as a crossover) Spur (also known as a hook) Double bifurcation

Ending Ridge A simple straight ridge that ends

Bifurcations and Trifurcations A ridge that splits into two ridges at the end Trifurcations: Just like bifurcations but split into three ridges at the end

Dots and Short Ridges Dots – tiny round ridges Short ridge – a small, isolated segment of ridge

Enclosure A ridge that forks and forms a complete circle and then becomes a single ridge again

Taken together, the ridge characteristics of a fingerprint Taken together, the ridge characteristics of a fingerprint. The types and locations of specific minutiae impart the uniqueness that is the basis for comparison of fingerprints. Minutiae