Which best describes the peronychium?

The peronychium is best described as the skin surrounding the nail. This term specifically refers to the area of living skin that borders the sides of the nail plate and covers the nail folds. This protective skin plays a crucial role as it helps shield the underlying nail bed and matrix from infections and injuries.

The other options do not accurately define the peronychium. The nail matrix refers to the tissue where the nail grows from, while the free edge is the part of the nail that extends beyond the fingertip. The cuticle, on the other hand, pertains to the thin layer of skin that overlaps the nail plate at the base, which is also distinct from the peronychium. Understanding these specific definitions helps clarify the unique functions and characteristics of each part of the nail structure.