Corrugator supercilii muscle

The Corrugator supercilii is a small, narrow, pyramidal muscle, placed at the medial end of the eyebrow, beneath the Frontalis and Orbicularis oculi.

It arises from the medial end of the superciliary arch; and its fibers pass upward and lateralward, between the palpebral and orbital portions of the Orbicularis oculi, and are inserted into the deep surface of the skin, above the middle of the orbital arch.

Action
The Corrugator draws the eyebrow downward and medialward, producing the vertical wrinkles of the forehead.

It is the “frowning” muscle, and may be regarded as the principal muscle in the expression of suffering.