Walsh & Hoyt: Levator Palpebrae Superioris

The levator palpebrae superioris arises as a short tendon that is blended with the underlying origin of the superior rectus from the undersurface of the lesser wing of the sphenoid bone, above and anterior to the optic foramen. The flat muscle belly passes forward below the orbital roof and just superior to the superior rectus until it is about 1 cm behind the orbital septum, where it ends in a membranous expansion or aponeurosis. The aponeurosis of the levator spreads out in a fan-shaped manner across the width of the eyelid, inserting primarily into the tarsal plate that separates the bundles of the orbicularis oculi muscle in the lower half of the eyelid. The lateral and medial extensions of the aponeurosis are its lateral and medial horns. The lateral horn is attached to the orbital tubercle and to the upper aspect of the lateral canthal ligament. The medial horn is attached to the medial canthal ligament.