Risorius

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Risorius
Muscles of the head, face, and neck.
Latin musculus risorius
Gray's subject #108 385
Origin: parotid fascia
Insertion: modiolus
Artery: facial artery
Nerve: Buccal branch of the facial nerve
Action: draw back angle of mouth
Dorlands/Elsevier m_22/12550552

The risorius arises in the fascia over the parotid gland and, passing horizontally forward, superficial to the platysma, inserts onto the skin at the angle of the mouth. It is a narrow bundle of fibers, broadest at its origin, but varies much in its size and form.

Action

The risorius retracts the angle of the mouth to produce a smile, albeit an insincere-looking one that does not involve the skin around the eyes. Compare with a real smile, which raises the lips with the action of zygomaticus major and zygomaticus minor muscles and causes "crow's feet" around the eyes using the orbicularis oculi muscles.

Innervation

Like all muscles of facial expression, the risorius is innervated by the facial nerve (CN VII).

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

hu:Nevetőizom sr:Мишић смеха


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