Final answer:
The tracks on either side of the nail that the nail moves on as it grows are called the nail grooves. These grooves guide the nail as it grows, allowing it to stay attached to the nail bed and protect the underlying tissues.
Step-by-step explanation:
The tracks on either side of the nail that the nail moves on as it grows are called the nail grooves.
The nail grows from a deep layer of living epidermal tissue known as the nail matrix at the proximal end of the nail. The nail matrix surrounds the nail root and contains stem cells that divide to form keratinocytes, which make up the nail.
These grooves are responsible for guiding the nail as it grows, allowing it to stay attached to the nail bed and protecting the underlying tissues.