Babinski Sign: What It Reveals About Your Brain

Added: 2026-05-25

[00:00:00]If you press the outside of someone's foot, and their big toe goes up instead of curling down, that could actually be a sign something is wrong in their brain. It is called the Babinski sign, and most people have never heard of it.

[00:00:11]Here is why it matters. We are all born with something called primitive reflexes. As we develop, the upper part of our motor system suppresses those reflexes, usually by age two. When you apply firm pressure along the outside of the foot toward the ball, a normal adult response is for the toes to curl downward. But, if the big toe extends upward, and the smaller toes fan outward, that is the primitive reflex returning. That pattern, known as a positive Babinski sign, can indicate damage or dysfunction in the brain or upper motor neurons that have lost the ability to keep that reflex suppressed.