The shape or thickness of the nail plate can change due to disease, injury, or infection occurring in the?

The matrix is the tissue under the base of the nail that is responsible for the production of new nail cells, which ultimately form the nail plate. When there is a disease, injury, or infection affecting the matrix, it can disrupt the normal growth and structure of the nail. This can result in noticeable changes in the shape or thickness of the nail plate.

For instance, if the matrix is damaged, it may lead to conditions such as ridging, pitting, or even deformity of the nail. Since the matrix directly influences nail formation, any alteration in its health or condition profoundly affects the nail plate above it. This makes the matrix the critical area concerning changes in the nail's characteristics due to various external or internal factors.