American Academy of Professional Coders (AAPC) Practice Exam

Which structure is located beneath the skin behind the fingernail?

1. Nail plate

2. Eponychium

3. Root

4. Nail bed

The correct answer is: Root

The structure located beneath the skin behind the fingernail is the root. The root of the nail, also known as the matrix, is where nail growth originates. It is situated under the cuticle area, providing the foundation for the nail plate above it. This area is crucial because it contains the cells that produce the keratin that makes up the nail. Understanding this anatomical context helps in recognizing the role of the root in nail health and growth. The nail bed, while also important, is the skin beneath the nail plate and does not reside behind the fingernail; rather, it supports the nail plate from below. The eponychium refers to the skin that overlaps the base of the nail; it does not lie beneath the skin behind the nail but serves as a protective barrier for the nail matrix. The nail plate is the visible part of the nail that we typically see, resting above the nail bed and extending from the root to the tip.