What Body Part Doesn’t Grow?

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The only human body part that does not grow after birth is the ossicular chain, which is composed of three small bones and is located in the middle ear. These bones are also the smallest lightest bones in the human body. Each bone is smaller than a grain of rice. The stapes is the smallest and is only 2.8 millimeters or 0.11 inch long.

Attached to the eardrum, these tiny bones work together to transmit vibrations from sound waves to the fluid in the inner ear. They are found in the middle ears of all mammals. These bones, named after the objects they resemble, are the malleus, or hammer, the incus, or anvil, and the stapes, or stirrup.

A common misconception is that the eyes do not grow from infancy. However, the human eye grows about one-third in size. At birth, the eyeball is 16 millimeters wide, but it grows to 23 millimeters in width by the age of 3 years. Eyes reach their maximum size at puberty, growing to be approximately 24 millimeters wide each.

Humans are born with about 300 bones. However, because some bones fuse together in the course of development, the adult human body has only 206 bones.