Nails are part of the integumentary system – which also includes the skin and hair. The integumentary system protects deeper tissues, waterproofs, and has many other functions such as sensory reception. The nail is made up of the nail plate, the nail matrix – from which the nail grows, and the nail bed – which is skin beneath the nail plate. Let’s discuss each of these. The nail plate is made up of translucent keratin protein, and appears pink due to the colour of the nail bed below. It has a free margin – the distal end of the nail that you clip every once in a while.
The nail matrix, which is at the nail’s proximal end, continually produces new cells, pushing older cells up and forward. These cells become flat, compressed, and translucent as they undergo keratinization – a process in which their cytoplasm is replaced by keratin protein filaments and then the cells die. The lunula – which is light in colour and crescent-shaped – is the visible portion of the nail matrix. The light colour of the lunula is thanks to its cells not having lost their nucleus yet in the nail bed-producing process. Meanwhile, the nail plate, which contains keratinized cells further along in the nail growing process, lacks nuclei, and is more translucent.
The nail bed has two layers – an epidermis located immediately beneath the nail plate, which moves towards the distal end of the finger with the nail plate, and a deeper dermis, which is living tissue containing glands and capillaries.
Mirroring the action of the nail plate and the nail matrix are the cuticle and the eponychium. The cuticle is composed of dead skin cells. The eponychium is a small band of living cells that sheds an epidermal layer of skin onto the newly formed nail plate. Together, they form a protective seal between the top of your nail and the skin at its boundary.
And now for one last anatomical feature I’d like to point out. Underneath the free end of your nail is a layer of epithelium called the hyponychium.
To finish off, here are some fun facts about your nails: the nails on your fingers grow faster than those on your toes. Nails on longer fingers also grow more quickly. So do nails that get bitten. Nails also grow faster during the summer than in the winter. The slowest your nails will ever grow is until age 4.
