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Levator labii superioris muscle

The Levator labii superioris muscle is a slender, flat facial muscle located in the midface. Primarily responsible for elevating the upper lip, this muscle plays a key role in facial expressions such as showing contempt or sadness. It forms part of the complex muscular framework that enables nuanced movement and expression of the upper lip and nose. Clinically, knowledge of its anatomy and imaging appearance is essential for evaluating facial trauma, nerve injury, and pathologies affecting facial movement.

Synonyms

  • Quadratus labii superioris (historic/obsolete)

  • Levator labii superioris alaeque nasi (closely related but distinct muscle)

  • Upper lip elevator (descriptive, non-technical)

Function

  • Elevates the upper lip

  • Contributes to facial expressions such as disdain, sadness, and sneering

  • Assists in dilating the nostril (in conjunction with the levator labii superioris alaeque nasi)

Origin

  • Infraorbital margin of the maxilla, just above the infraorbital foramen

Insertion

  • Skin of the upper lip

  • Lateral part of the upper lip at the orbicularis oris muscle

  • Some fibers blend with those of the levator labii superioris alaeque nasi and zygomaticus minor

Nerve Supply

  • Facial nerve (Cranial Nerve VII)
    Specifically, the buccal branch of the facial nerve

Artery Supply

  • Facial artery (superior labial branch)

  • Infraorbital artery (branch of the maxillary artery)

Vein Supply

  • Facial vein (superior labial vein)

  • Infraorbital vein

MRI Appearance

  • T1-weighted images:
    Appears as an intermediate to low signal intensity structure, distinguishing muscle from surrounding fat and connective tissue.

  • T2-weighted images:
    Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery):
    Muscle shows low signal intensity in healthy tissue; hyperintensity is seen if there is edema, inflammation, or acute injury.

CT Appearance

  • Appears as a soft tissue density muscle band, running from the infraorbital margin to the upper lip

  • Can be visualized more distinctly with contrast enhancement or in cases of trauma/swelling

MRI images

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