Corrugator supercilii muscle

The corrugator supercilii muscle is a small, narrow, pyramidal muscle of the face. It arises from the medial end of the superciliary arch; it inserts into the deep surface of the skin of the eyebrow.

It draws the eyebrow downward and medially, producing the vertical "frowning" wrinkles of the forehead. It may be thought as the principal muscle in the facial expression of suffering. It also shields the eyes from strong sunlight.

Structure
The corrugator supercilii muscle is located at the medial end of the eyebrow. Its fibers pass laterally and somewhat superiorly from its origin to its insertion.

Origin
It arises from bone at the medial extremity of the superciliary arch.

Insertion
It inserts between the palpebral and orbital portions of the orbicularis oculi muscle. It inserts into the deep surface of the skin of the eyebrow, above the middle of the orbital arch.

Innervation
Motor innervation is provided by the temporal branches of facial nerve (CN VII).

Vasculature
The muscle receives arterial supply from adjacent arteries - mostly from the superficial temporal artery, and the ophthalmic artery.

Relations
It is situated deep to the frontalis muscle (of the occipitofrontalis muscle) and orbicularis oculi muscle, Its fibres are situated between the palpebral and orbital portions of the orbicularis oculi muscle.

The supratrochlear nerve passes between this muscle and the frontalis muscle.

Function
The muscle acts in tandem with the orbicularis oculi muscle. The corrugator supercilii muscle acts upon the skin of the forehead superior to the middle of the supraorbital margin, drawing the eyebrow inferomedially to produce vertical wrinkles of the forehead just superior to the nose. It is the "frowning" muscle, and may be regarded as the principal muscle in the expression of suffering. It also contracts to prevent high sun glare, pulling the eyebrows toward the bridge of the nose, making a roof over the area above the middle corner of the eye and typical forehead furrows to shield the eye from excessively bright sunlight.

Clinical significance
The muscle is sometimes surgically severed or paralysed with botulinum toxin as a preventive treatment for some types of migraine or for aesthetic reasons.

Etymology
The name corrugator supercilii comes from Latin, and means wrinkler of the eyebrows.