The Surprising Journey Of A Dead Nail: A Tale Of Growth And Decay

Fingernails grow by an average of 0.1mm per day, a rate which slows as we age. Continuous division of matrix cells pushes the nail plate forward over the nail bed at a rate of about 3 millimeters [0.1 inches] per month for fingernails, and 1 millimeter [0.04 inches] per month for toenails.

Keratin cells form at the root and push the nail plate forward

Keratin cells form at the root of our fingernails and toe nails, just beneath the skin, and push the nail plate forward as they grow. The root is also known as the matrix and is a pocket of flesh that connects to blood vessels, which supply the nail with the nutrients it needs to make new cells.

The continuous division of matrix cells pushes the nail plate forward over the nail bed at a rate of about 3 millimeters [0.1 inches] per month for fingernails, and 1 millimeter [0.04 inches] per month for toenails.

Nails are made of a tough, dead substance called keratin, the same material that makes up hair. But nails actually start out as living cells.

Evolutionarily, researchers think nails come into this equation because they acted like a kind of scaffold for the broad, fleshy pads of the fingers and toes. That structure maintained the wide shape of the digits and increased the surface area of the pad: When pressed down, the flesh of fingers and toes would have been flattened against the nail. By supporting this enlarged surface area, nails improved our ancestors' grip and enabled them to move more confidently through the trees.

Nails also have a protective evolutionary function — working like miniature shields that cover the exposed tips of our fingers and toes. Our digits are packed with thousands of nerves, which transform them into highly sensitive tools for detecting the world around us.

Nails act as a scaffold for broad, fleshy pads of fingers and toes

Nails also have a protective evolutionary function — working like miniature shields that cover the exposed tips of our fingers and toes. Our digits are packed with thousands of nerves, which transform them into highly sensitive tools for detecting the world around us. If you look at the regions of the brain that primates have committed to the sense of touch from their digits, compared to the amount of space in, say, a cat's brain, primates have lots and lots of space. That points to the importance of these appendages in helping primates to dexterously feel and navigate their way around the world — and thus, the crucial importance of nails in protecting and preserving that function by shielding them from harm.

Behind the cuticles on fingers and toes, just beneath the skin, a structure called the "root" churns out living cells that go on to form the nail. Also known as the matrix, this little pocket of flesh connects to blood vessels, which supply the nail with the nutrients it needs to make new cells. Continuous division of matrix cells pushes the nail plate forward over the nail bed at a rate of about 3 millimeters [0.1 inches] per month for fingernails, and 1 millimeter [0.04 inches] per month for toenails.

As keratin cells form at the root, they're slowly pushed forward by newly-formed cells jostling for space behind them. Edged out from beneath the skin and into the open, the older cells flatten and harden to form the tough shield of the nail plate. After the heart stops beating, oxygen supply to the brain is cut off. With no glucose store to rely on, nerve cells die within three to seven minutes. Transplant surgeons must remove kidneys, livers and hearts from donors within thirty minutes of death and get them into recipients inside six hours. Grafts can still be successful if taken 12 hours after death. In order for fingernails to grow, new cells need to be produced and this can’t happen without glucose.

Nails protect the tips of fingers and toes from harm

Nails also have a protective evolutionary function — working like miniature shields that cover the exposed tips of our fingers and toes. Our digits are packed with thousands of nerves, which transform them into highly sensitive tools for detecting the world around us. If you look at the regions of the brain that primates have committed to the sense of touch from their digits, compared to the amount of space in, say, a cat's brain, primates have lots and lots of space. That points to the importance of these appendages in helping primates to dexterously feel and navigate their way around the world — and thus, the crucial importance of nails in protecting and preserving that function by shielding them from harm.

Nails are made of a tough, dead substance called keratin, the same material that makes up hair. But nails actually start out as living cells. Behind the cuticles on fingers and toes, just beneath the skin, a structure called the "root" churns out living cells that go on to form the nail. Also known as the matrix, this little pocket of flesh connects to blood vessels, which supply the nail with the nutrients it needs to make new cells.

As keratin cells form at the root, they're slowly pushed forward by newly-formed cells jostling for space behind them. Continuous division of matrix cells pushes the nail plate forward over the nail bed at a rate of about 3 millimeters [0.1 inches] per month for fingernails, and 1 millimeter [0.04 inches] per month for toe nails.

Nails grow by an average of 0.1mm per day

Fingernails grow by an average of 0.1mm per day, a rate which slows as we age. Continuous division of matrix cells pushes the nail plate forward over the nail bed at this rate. Nails are made of a tough, dead substance called keratin, the same material that makes up hair. Behind the cuticles on fingers and toes, just beneath the skin, a structure called the "root" churns out living cells that go on to form the nail. Also known as the matrix, this little pocket of flesh connects to blood vessels, which supply the nail with the nutrients it needs to make new cells. As keratin cells form at the root, they're slowly pushed forward by newly-formed cells jostling for space behind them.

Nails also have a protective evolutionary function — working like miniature shields that cover the exposed tips of our fingers and toes. Our digits are packed with thousands of nerves, which transform them into highly sensitive tools for detecting the world around us. Researchers think nails come into this equation because they acted like a kind of scaffold for the broad, fleshy pads of the fingers and toes. That structure maintained the wide shape of the digits and increased the surface area of the pad: When pressed down, the flesh of fingers and toes would have been flattened against the nail. By supporting this enlarged surface area, nails improved our ancestors' grip and enabled them to move more confidently through the trees.

When it came to foraging for food, our wide fingers and toes would have been especially handy, Borths noted. Evolutionarily-speaking, researchers think nails come into this equation because they acted like a kind of scaffold for the broad, fleshy pads of the fingers and toes. That structure maintained the wide shape of the digits and increased the surface area of the pad: When pressed down, the flesh of fingers and toes would have been flattened against the nail. By supporting this enlarged surface area, nails improved our ancestors' grip and enabled them to move more confidently through the trees.

In order for fingernails to grow, new cells need to be produced and this can’t happen without glucose. Fingernails grow by an average of 0.1mm per day, a rate which slows as we age. Continuous division of matrix cells pushes the nail plate forward over the nail bed at this rate. Nails are made of a tough, dead substance called keratin, the same material that makes up hair. Behind the cuticles on fingers and toes, just beneath the skin, a structure called the "root" churns out living cells that go on to form the nail. Also known as the matrix, this little pocket of flesh connects to blood vessels, which supply the nail with the nutrients it needs to make new cells. As keratin cells form at the root, they're slowly pushed forward by newly-formed cells jostling for space behind them.

Nails require glucose to grow and can't grow without it

Fingernails grow by an average of 0.1mm per day, a rate which slows as we age. Continuous division of matrix cells pushes the nail plate forward over the nail bed at a rate of about 3 millimeters [0.1 inches] per month for fingernails, and 1 millimeter [0.04 inches] per month for toenails.

Nails are made of a tough, dead substance called keratin, the same material that makes up hair. But nails actually start out as living cells. Behind the cuticles on fingers and toes, just beneath the skin, a structure called the "root" churns out living cells that go on to form the nail. Also known as the matrix, this little pocket of flesh connects to blood vessels, which supply the nail with the nutrients it needs to make new cells.

As keratin cells form at the root, they're slowly pushed forward by newly-formed cells jostling for space behind them.

In order for fingernails to grow, new cells need to be produced and this can’t happen without glucose. After the heart stops beating, oxygen supply to the brain is cut off. With no glucose store to rely on, nerve cells die within three to seven minutes.

Researchers posit that nails also have a protective evolutionary function — working like miniature shields that cover the exposed tips of our fingers and toes. Our digits are packed with thousands of nerves, which transform them into highly sensitive tools for detecting the world around us.

Frequently asked questions