5 Chapter 5: The Integument – Fingerprinting

Background

Fingerprints are unique patterns formed by the ridges and furrows on the surface of the skin on our fingertips. They are used in forensic science for identification purposes due to their uniqueness and permanence. There are three main types of fingerprint patterns: loops, whorls, and arches. Fingerprints are also known as friction ridges, or epidermal ridges. They interlace with dermal papillae of the dermis in the skin on the volar surface of the hands and feet.

The integumentary system includes the hair, skin, and nails.  In these activities, you will  perform fingerprints, view and size a small strand of your own hair, and label one of your fingernails, and perform fingerprints.

Activity 5.1 Fingerprint Identification and Scoring

Definitions:

Roll Print: A roll print captures the entire ridge detail of a finger. This technique involves rolling the fingertip from one side to the other across the inked surface.

Regular Print: A regular print is a flat impression of the fingertip pressed onto the surface. This technique captures the central portion of the fingertip, but may not include the full ridge detail.

Fingerprint Patterns

• Loops: Ridges that enter from one side, curve around, and exit the same side.
• Whorls: Circular or spiral patterns.
• Arches: Ridges that enter from one side and exit the other, without looping back.

Materials Needed

• Fingerprint cards
• Ink pads
• Magnifying glasses
• Towelettes for cleaning
• Writing utensils (pens or pencils) for labeling

Instructions

Step 1: Preparing Your Work Area

• Set up your workspace by laying out the fingerprint cards, ink pads, magnifying glasses, and towelettes.
• Ensure that each student has enough space to work comfortably.

 Creating a Roll Prints

1. Choose a Finger: Start with one finger from one hand, preferably the index finger.
2. Ink the Finger: Gently press your fingertip onto the ink pad to cover the entire surface with ink. Be careful not to apply too much pressure.
3. Position the Finger: Hold the fingerprint card horizontally with the labeled sections facing you.
4. Roll the Finger:
   • Place the inked fingertip on one side of the designated area on the fingerprint card.
   • Roll your finger from one side to the other, ensuring the entire fingertip makes contact with the card.
   • Lift your finger straight off the card without smudging it.
5. Label the Print: Write the corresponding finger (e.g., left index) next to the print.

Creating Regular Prints

1. Choose Additional Fingers: Select four other fingers from the same hand (e.g., middle, ring, pinky, and thumb).
2. Ink Each Finger: Repeat the inking process for each selected finger.
3. Press for Regular Prints:
   • For each finger, press the inked fingertip straight down onto the fingerprint card in the designated areas without rolling.
   • Ensure you apply enough pressure to capture the ridge details.
4. Label Each Print: Write the corresponding finger next to each print if you’re not using a fingerprint card.

Identifying Fingerprint Patterns

1. Examine Your Prints: Use the magnifying glass to examine the details of each fingerprint you created.
2. Identify Patterns: For each finger, determine whether the print is a loop, whorl, or arch.
3. Record Your Findings: Write down the pattern type next to each fingerprint on your fingerprint card.

Scoring Your Prints – Use the method described by your instructor

Clean Up – Be sure to keep your workspace clean. Wipe the area where you created your print with disinfectant.

• Use the towelettes to clean your hands after the activity.
• Return all materials to their designated places.

Activity 5.2

Instructions:

Obtain one strand of your hair and take a picture of it under the microscope at 10X or 40X with the micrometer visible and next to the width of the hair showing how it lines up with the ruler. Label the parts of the hair visible. Find the width of the hair and include it on your snapshot as total magnification.   Upload a labeled snapshot to your LMS. Be sure to include the

Activity 5.3

Take a lateral, ventral, and posterior view picture of one of the tip of your finger. You can choose which nail. You should choose a nail that has a lunula.  Label all the following structures: lunula,  nail fold, free edge, eponychium, and nail body. If one of these structures are not visible from a lateral view, do not label it.  Upload the labeled snapshots to your LMS.