Final answer:
The part of the hair between the scalp and previously colored hair is called the cortex, which is the middle zone of the hair shaft and consists of dead cells.
Step-by-step explanation:
The hair shaft between the scalp and hair that has been previously colored is called the cortex. The hair shaft has three zones: the cuticle, which is the outermost layer; the cortex, which is the middle layer; and the medulla, which is the innermost layer. The section of hair that is within the follicle is the hair root, which is the only living part of the hair. The hair shaft, which you can see above the skin's surface, is composed of dead cells. Hair growth initiates at the basal cells of the hair bulb, and as keratinocytes are produced, they push the hair shaft up through the follicle, eventually leading to the keratinized cells that form the visible hair shaft.