What part of the nail determines its shape and growth?

The matrix is the critical area at the base of the nail underneath the cuticle, and it plays a significant role in determining both the shape and growth of the nail. This specialized tissue generates new nail cells, pushing older ones out and resulting in the visible nail we see. The health and condition of the matrix directly affect nail growth and shape; if the matrix is damaged, it can lead to irregularities in the nail that may affect how it grows in the future.

Other components like the nail bed, plate, and lunula have their functions, but they don’t directly control the nail's shape and growth. The bed supports the nail and provides nourishment but does not produce the nail itself. The nail plate is the hard part of the nail that we see and feel, while the lunula is the visible part of the matrix at the base of the nail. Thus, the matrix is essential for the overall development of the nail itself.