Corrugator supercilii muscle
Encyclopedia
The Corrugator supercilii is a small, narrow, pyramidal muscle, placed at the medial end of the eyebrow
Eyebrow
The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some mammals. Their main function is to prevent sweat, water, and other debris from falling down into the eye socket, but they are also important to human communication and...

, beneath the Frontalis
Frontalis muscle
The Frontalis muscle , also known as the occipitofrontalis or epicranius, is thin, of a quadrilateral form, and intimately adherent to the superficial fascia. It is broader than the Occipitalis and its fibers are longer and paler in color...

 and just above Orbicularis oculi
Orbicularis oculi muscle
The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament.From...

.

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
Eyebrow
The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some mammals. Their main function is to prevent sweat, water, and other debris from falling down into the eye socket, but they are also important to human communication and...

 downward and medialward, producing the vertical wrinkles of the forehead
Forehead
For the Arsenal striker see GervinhoIn human anatomy, the forehead is the fore part of the head. It is, formally, an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp...

. It is the “frowning” muscle, and may be regarded as the principal muscle in the expression of suffering
Suffering
Suffering, or pain in a broad sense, is an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Suffering may be qualified as physical or mental. It may come in all degrees of intensity, from mild to intolerable. Factors of duration and...

. It also contracts in order 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.

The muscle is sometimes surgically severed or paralysed with botulinum toxin
Botulinum toxin
Botulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...

 as a preventive treatment for some types of migraine
Migraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...

or for aesthetic reasons.
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