Lecture 8 - Friction ridge examination Flashcards
What is the function of skin?
Protection and a barrier to infection. Ridges assist in grip
When do volar pads start to develop on the fingertips
After 7-8 weeks
When do ridges start to form?
After 10.5 weeks
How do ridges form?
The pattern is determined by the rise and fall of volar pads, influenced by genetics, environmental factors, pressure and movement
Primary ridges
Ridges on the bottom of the epidermis under the surface friction ridges
Secondary ridges
Ridges on the bottom of the epidermis under the surface furrows/valleys
Where are eccrine glands located?
Palmar (hand) and plantar (foot) surfaces
What do eccrine glands on hand and foot surfaces secrete?
Mostly water and some inorganic substances
Where are sebaceous glands located?
Within the hair follicle
What does the eccrine gland, located within the hair follicle, secrete?
Produces sebum, a fatty wax of lipids and fatty acids, tryglycerides and wax esters
Where is the apocrine gland located?
Pubic and underarm areas
What does the apocrine gland, located in pubic and underarm areas, secrete?
Proteins, carbohydrates, cholesterol and iron
What type of surface allows fingerprints to soak in?
Porous surface such as paper, cardboard and fabric
What type of surface allows fingerprint to sit on surface and slowly absorb?
Semi-porous surface, such as a waxed or varnished surface and painted walls
What type of surfaces allows fingerprints to sit on top and be easily wiped off?
Non-porous surface, such as metal surfaces, glass and plastic
What method of enhancing fingerprints requires no treatment and is the least destructive?
Optical observation through using oblique lighting
What are the main powders used to adhere to fingerprints to enhance visualisation?
White, black, aluminum, magnetic and fluorescent
What chemical processing is used to develop fingerprints on porous surfaces by reacting with amino acids?
Ninhydrin. Develops a purple fingerprint
What chemical processing is used to develop fingerprints on non-porous surfaces by reacting with moisture?
Cyanoacrylate. Develops a white fingerprint
What chemical processing is used to develop fingerprints on non-porous surfaces by reacting with proteins?
Amido black. Develops a dark blue fingerprint and destroys the DNA
What methods are used to collect fingerprints from recently deceased bodies?
Digital photography, ink and mortuary spoon, powder and tape
What methods are used to collect fingerprints from bodies in early decomposition?
Gloving and dermal identification
What methods are used to collect fingerprints from bodies in advanced decomposition?
Alcohol to dry the skin and casting
