Which factors are used to calculate the medullary index of the hair?

The medullary index of hair is calculated by comparing the diameter of the medulla (the central core) to the diameter of the entire hair shaft. Specifically, the formula is: Medullary Index = Diameter of Medulla / Diameter of Hair Shaft. This index helps in distinguishing between different types of hair, as it varies among species and can indicate whether the hair is from a human or an animal.