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14 Cards in this Set
- Front
- Back
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What are some of the factors that contribute to general ridge flow and pattern formation?
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Growth stresses on the skin. The size and shape of the volar pads, as well as their symmetry and height.
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What factors affect volar pad shape and size?
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Heredity/genetic factors. The developmental growth of the hand. Intrauterine stresses, disease and drug/alcohol abuse. Direct stresses due to growth.
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How does volar pad location and size/symmetry affect friction ridge formations?
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Large and evenly shaped pads will create whorl type patterns, while offset pads will create loop or tented arch patterns. Low or small pads will create arch patterns.
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How does the timing of volar pad regression affect friction ridge development?
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When primary ridge development starts before regression, it will result in a high ridge count. If it occurs after after regression, the ridge count will be lower and will result in arch patterns.
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What are vestiges?
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They are erratic local disarrangement of ridges that do not conform to surrounding ridges. They are due to irregular shapes of the palmar volar pads.
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How does friction ridge length contribute to uniqueness?
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The number of ridge units in each ridge varies, with each unit containing a pore, pore duct and sweat gland.
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What do major ridge path deviations result in?
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Branches that become bifurcations and islands, both short and long. Known as 2nd level detail.
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What governs the placement of 2nd level detail such as bifurcations?
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A random series of infinitely interdependent stresses, strains and tensions across that specific area at that critical moment.
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What are incipient ridges?
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Immature ridges that correspond to a primary ridge. They are thinner and more fragmented, and usually do not have fully developed pore formations.
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What are the 3 random factors that contribute to uniqueness?
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Random timing of events. Random growth processes. Random pressures.
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Describe the random timing of events as it applies to differential growth.
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The timing of the onset of primary ridge development in conjunction with the regression of the volar pads. The timing of the onset of secondary ridge development.
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Describe the random growth processes as they apply to differential growth.
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The number of units in a ridge, it's path and start/stop points are random, as is the thickness and height. Alignment, bifurcation and misalignment are all random, as well as pore location.
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Describe the random pressures as they apply to differential growth.
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Pressure from the size and shape of the volar pads. Pressure from neighboring ridges. Pressures in the womb. Numerous genetic and physical pressures.
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Define or summarize differential growth.
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All the random growth aspects of friction skin that occurs from the onset of primary ridge development(10.5-12 weeks) up until the appearance of secondary ridges(15-17 weeks or time of differentiation).
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