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Levator anguli oris muscle

The Levator anguli oris is a small yet important facial muscle located in the upper lip region. It plays a vital role in facial expression, particularly in elevating the angle of the mouth to produce smiling or grimacing. This muscle is situated deep to the zygomaticus major and minor, and it contributes to the muscular modiolus at the angle of the mouth. The Levator anguli oris is closely associated with the muscles of the upper lip, enabling coordinated and nuanced movements of the mouth.

Synonyms

  • Caninus muscle

  • Musculus caninus

  • Elevator of the angle of the mouth

Function

  • Elevates the angle of the mouth medially

  • Assists in smiling and expressions of disdain or contempt

  • Works synergistically with other muscles of facial expression

Origin

  • Canine fossa of the maxilla (just below the infraorbital foramen)

Insertion

  • Modiolus at the angle of the mouth

  • Fibers blend with those of the orbicularis oris, depressor anguli oris, and zygomaticus muscles

Nerve Supply

  • Buccal branches of the facial nerve (cranial nerve VII)

Artery Supply

  • Superior labial branch of the facial artery

  • Infraorbital artery (branch of the maxillary artery)

Vein Drainage

  • Superior labial vein

  • Facial vein

MRI Appearance

  • T1-weighted images: Intermediate signal intensity, similar to other facial muscles

  • T2-weighted images: Intermediate signal intensity, similar to other facial muscles

  • STIR sequence: Hyperintense (bright) if inflamed, edematous, or pathologically involved; normally appears isointense to other facial muscles

CT Appearance

  • Appears as a thin, soft-tissue density band arising from the canine fossa of the maxilla and inserting at the angle of the mouth

  • Not easily distinguished from surrounding muscles unless contrast is used or in cases of pathology or trauma

MRI images

Levator anguli oris muscle MRI AXIAL IMAGE