eli5 why most people cant hold their hand still?



I’ve noticed that when trying to hold your hand as still as possible basically no one can do it. What causes this?

In: Biology

Blood flow and general muscle spasms are why most people can’t hold their hands perfectly still. Things are moving in your arms at all times. This causes minor movements.

It actually takes energy to hold your hand flat. Our natural “relaxed” pose is a semi-curled position with the fingers pointed in at the palms.

You have several reflexes that are invoked the moment your ligaments stretch in your hand. The grasp reflex is chief among them. This is most obvious in newborn babies – if you touch their palm their fingers will snap shut and hold tightly. As we age, our brain overrides this reflex, but it never actually vanishes.

The small movements you see are this reflex and several others in action, being actively overridden by the brain. The reflex-override results in tiny twitches or shakes.

Thought it had to do with body chemistry as well. How much metal and salt in your nerves moving signals up in sensory input and down in muscle control.