Re: What body part or organ stays the same size from birth?

Hi Jamie,

Interesting question. I have a feeling you may have a follow up to my response. I believe that Steve Mack at madscientist has provided the best answer: The spinal cord. In the human fetus, the spinal cord extends all the way down to the sacral vertebrae (the very end). As a person ages, the spinal cord shortens relative to the rest of the body so at adulthood the spinal cord only reaches down to around the level of L1 (lumbar 1). Neuroanatomy is one of my best subjects....any related questions will be gladly received!

There is maybe a less obvious answer. The eyes. I have to admit though, a babies eyes are about 75% of what they will become as an adult. So they are technically not the same size from birth, but pretty close. With that said, we'll stick to the spinal cord as the best answer. I hope this response satisfies you question. If not, might I suggest you submit a more specific question?

Brian Bauereis

[Moderator's Note: These answers, 937854003.An and 1141746701.An, in our archives discuss changes in the size of the eyeball from birth to adulthood.]