A cheek dimple can come from a variation in a smiling muscle

How a split cheek muscle makes a dimple

A smile begins when muscles pull the corners of the mouth upward. One of the main muscles involved, the zygomaticus major, runs from the cheekbone toward the corner of the mouth. In some people, this muscle has a split or an extra attachment to the skin of the cheek.

That attachment acts like a small tether. As the muscle contracts, it pulls the skin inward at one point instead of lifting it smoothly, creating the visible hollow called a dimple.

Why the hollow appears when you smile

At rest, the skin may lie relatively flat. When the muscle tightens, the tether draws it inward, so the dimple becomes more noticeable. Its position and shape depend on where the muscle attaches and how the surrounding skin and tissue move.

This is a natural variation in facial anatomy, not a separate muscle or a mark in the skin itself. The same small pull that helps move the mouth can leave a distinctive indentation each time a person smiles.