Fiber Structure and Identification

This video tutorial covers the basics of visual identification of hair and fiber evidence. It explains the differences between hairs and fibers, focusing on their shapes, patterns, and microscopic features. The tutorial discusses how forensic scientists use these characteristics to analyze evidence, determine the type of fiber, and identify whether hair is human or non-human. The video also highlights the structural features of hair, such as the cuticle and medula, and the uniformity of synthetic fibers compared to the irregularity of natural fibers.

What is a key difference between synthetic and natural fibers?

• Synthetic fibers are irregular in shape.

• Natural fibers are always circular.

• Synthetic fibers are very uniform in shape.

• Natural fibers have a medula.

Which structural feature is NOT found in fibers?

• Cuticle

• Medula

• Scales

• Uniform shape

What cuticle pattern is common in small rodents and bats?

• Spinus

• Imbricate

• Coronal

• Circular

Which species has a spinus cuticle pattern?

• Bats

• Cats

• Humans

• Dogs

What is the medular index used for?

• Determining fiber type

• Measuring hair length

• Identifying cuticle patterns

• Differentiating between human and animal hair

What is a characteristic of synthetic fibers?

• They have a cuticle.

• They have a medula.

• They are uniform in shape.

• They are irregular in shape.

Which of the following is a natural fiber?

• Acrylic

• Fiberglass

• Polyester

• Cotton

What shape do trilobal synthetic fibers have?

• Circular

• Hollow

• Dog bone

• Trilobal

What is a unique feature of acrylic fibers?

• They are flat and ribbonlike.

• They are perfectly circular.

• They have a dog bone shape.

• They have a spinus pattern.

How can you differentiate between circular animal hairs and circular synthetic fibers?

• By checking for a medula

• By examining the cuticle pattern

• By measuring the fiber length

• By observing the color