What are the tracks on both sides of the nail through which it moves as it grows called?

The tracks on both sides of the nail that guide its growth are referred to as grooves. Grooves serve as channels for the nail as it extends and helps maintain its positioning. This anatomical feature is crucial for the proper growth of the nail, ensuring that it develops evenly along the nail bed and prevents overgrowth or misalignment.

The other terms do not accurately describe these structures. "Tracks" are too vague and do not have a specific definition in nail anatomy. "Folds" typically refer to the skin or tissues that may encase parts of the nail but do not specifically denote the growing paths of the nail. "Beds" generally refer to the nail bed itself, which is the skin beneath the nail and doesn’t relate specifically to the grooves that guide nail growth. Thus, grooves is the correct terminology to describe the anatomical features involved in nail movement as it grows.