eli5: How do we close our eyelids?

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As I understand, muscles only work by contracting and pulling, so they work in pairs, or more, to move joints in different directions.

How then, do they pull your eyelid down over your eye?

In: Biology

Anonymous 0 Comments

Think of muscles as two-way. They’re strongest when they contract and pull. But when they relax, that has a weak pushing effect.

So your eyelids are controlled by two muscles. One is designed to pull them open and we fully control this muscle. The other is designed to push them down when we relax the other muscle, this one’s more subconscious.

Since the eyelid is a very small bit of skin, it doesn’t take much force to move it so a relaxing muscle is enough.

Pay attention when you try to close your eyes really hard. You’ll find that you’re really just pushing really hard with the muscles around your eye sockets, and that even when you’re clenching very hard it doesn’t take a lot of force to push your eyelids back open.

Or, try to hold one eyelid up and close your eyes. You’ll feel your eyebrow move, but not a lot of force from the eyelid itself.

You don’t really have any muscles that push it down with a lot of force.