Structure Of Nails - Function Of Nails - Anatomy Of Nails - Why Do We Have Nails

In this video we discuss the structure of fingernails and toenails. We cover the different parts of nails and how nails grow. We also discuss some of the functions of nails.


Transcript/notes

Nails

Both fingernails and toenails are made up of heavily keratinized epidermal cells. Keratinized cells being cells that were once alive, but filled with the keratin protein as they matured, causing them to lose their organelles and die.

From the top view of a nail, the outermost whiteish part is called the free edge. The next pinkish section is the nail body. It has this pinkish color because of the blood flowing in the capillaries below it. The lighter pink crescent shaped area of the nail is called the lunula. The narrow band of skin that extends onto the nail body is called the cuticle or eponychium, and the nail root which is not visible extends inwards, under the skin towards the palm of the hand.

From the side view we see the sections we just mentioned, the free edge, the nail body, the lunula, the cuticle and the nail root. The nail bed is located here, under the nail body, and it is composed of living cell layers. Toward the palm of the hand, the nail bed thickens to form the nail matrix which is the growing part of the nail. Nails grow by mitosis or cell division from beneath the lunula and root. There is also a thickened part of the skin where the free edge of the nail hangs over called the hyponychium.

Fingernails grow about 3 millimeters per month, and toenails grow about 1 mm per month, and it takes about 6 months for a fingernail to grow from the root to the free edge and 12 to 18 months for a toenail to grow from root to free edge. Both fingernails and toenails grow slightly faster in the summer it is believed that this is caused by more exposure to the sun and typically people are out and about, moving more, thus increasing circulation, producing more rapid nail growth.

Nails help to prevent damage to bones and the underlying soft tissue during certain movements such as kicking, jumping and catching. They also function to help us dig, climb and scratch an itch, and fingernails also help in grasping things.

Timestamps
0:00 Cells of fingernails and toenails
0:14 Structure of nails
1:13 Fingernail and toenail growth
1:41 Functions of nails in the body