The levator palpebrae superioris muscle is a triangular-shaped muscle known as the only muscle that elevates the superior eyelid. Most commonly, it arises from the annulus of Zinn and courses in an anterior direction along the roof of the orbit, traveling over the superior rectus muscle toward the upper eyelid.

It gradually becomes wider, and close to the upper eyelid becomes a tendon sheath known as the levator aponeurosis, which has several insertion sites.

Like the other extraocular muscles, the levator palpebrae superioris is also a striated skeletal muscle. However, the undersurface of the distal aspect of this muscle gives rise to a collection of smooth muscle cells collectively known as the superior tarsal muscle (Muller's muscle). The Muller's muscle is considered a part of the levator palpebrae superioris and is located within the upper eyelid.

Origin: annulus of Zinn and fibers of the superior rectus muscle at the annulus of Zinn. Alternatively, it may arise from the lesser wing of the sphenoid bone superior to the annulus of Zinn.

Insertion: anterior aspect of the superior tarsal plate of the upper eyelid, skin of the upper eyelid, superior conjunctival fornix.

Action: elevation and retraction of the upper eyelid.

Innervation: superior branch of the oculomotor nerve (CN III); superior tarsal muscle is innervated by the sympathetic nervous system.

Blood supply: superior muscular branch and supraorbital artery of the ophthalmic artery.

Venous drainage: superior and inferior orbital veins that further drain into the cavernous sinus.

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Levator palpebrae superioris