The medullary index is a ratio comparing the width of the medulla of a hair to the width of the hair shaft. It is determined by dividing the medulla’s diameter by the hair’s diameter. For example, if a hair has a medullary diameter of 50 micrometers and a hair shaft diameter of 100 micrometers, the resulting value would be 0.5.
This calculation is a valuable tool in forensic science and zoology. It assists in differentiating between human and animal hairs, as animals generally exhibit a higher proportional medulla width. In forensic investigations, it can narrow down the possible sources of hair samples found at crime scenes. This measurement, while simple, provides an important characteristic for identification and comparative analysis.
