The levator palpebrae superioris is the primary elevator of the upper eyelid, arising from the sphenoid bone above the superior rectus and running anteriorly to insert into the tarsal plate and upper eyelid skin via a wide aponeurosis. A deeper smooth muscle layer (Muller muscle, superior tarsal muscle) receives sympathetic innervation and contributes approximately 2 mm of additional lid elevation. The levator aponeurosis is a broad fascial sheet that fans out to insert into the tarsal plate and the skin of the upper eyelid crease.
| Origin | Inferior surface of the lesser wing of the sphenoid bone, anterior to the optic canal |
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| Insertion | Anterior surface of the tarsal plate of the upper eyelid and overlying upper eyelid skin |
| Nerve Supply | Oculomotor nerve (CN III), superior division; Sympathetic fibres (to superior tarsal / Muller muscle component) |
| Blood Supply | Ophthalmic artery; Lacrimal artery |
| Actions | Elevation of the upper eyelid (opens the eye) |
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Ptosis (drooping of the upper eyelid) results from failure of the levator palpebrae superioris from several causes: oculomotor nerve palsy (complete ptosis with the eye deviated down and out), sympathetic denervation in Horner syndrome (partial ptosis with miosis and anhidrosis), myasthenia gravis (fatigable ptosis), congenital levator hypoplasia, or involutional aponeurotic dehiscence in the elderly. Surgical correction involves levator resection or Mullerectomy for mild ptosis, or frontalis sling for complete levator palsy.
The muscle itself is not directly palpable, but the levator aponeurosis can be indirectly assessed by palpating the upper eyelid crease. Loss of the crease indicates aponeurotic dehiscence.
CN III palsy produces complete ipsilateral ptosis with the eye in a down-and-out position and a fixed dilated pupil if the nerve is compressed by an aneurysm or herniation, requiring urgent neuroimaging to exclude posterior communicating artery aneurysm.
Age-related dehiscence of the levator aponeurosis from the tarsal plate produces gradually progressive ptosis in the elderly, often with a high or absent upper eyelid skin crease and normal levator function, corrected by aponeurosis advancement under local anaesthesia.
Sympathetic denervation affecting Muller muscle produces mild 1-2 mm partial ptosis with ipsilateral miosis, anhidrosis, and enophthalmos, with the degree of ptosis used to localise the lesion and prompt investigation for a central, preganglionic, or postganglionic cause.
