The hair medulla, the innermost layer of the hair shaft, is a central core of cells that contain melanin, the pigment that gives hair its color. The medulla is responsible for the hair's stiffness and strength.
The medulla is important for the overall health and appearance of the hair. It helps to protect the hair from damage and breakage, and it also provides insulation. In addition, the medulla can help to determine the hair's texture and curl pattern.