The platysma

Platysma · platysma

A thin sheet of muscle in your neck that tightens the skin and pulls down the corners of your mouth.

What it does

The platysma is a broad, thin muscle lying just under the skin of the front of the neck. It runs from the upper chest to the jaw and the corners of the mouth. When you grimace, it tightens the neck skin into vertical cords.

Surprising fact

The platysma is a muscle of facial expression even though it lies mostly in the neck, and it is a remnant of a skin muscle that lets horses twitch their skin to shake off flies.