MCQ – 91787

Ptosis in Horner syndrome is due to paralysis of which muscle?

Correct Answer � A Explanation

– Horner syndrome: ptosis, miosis & anhidrosis on affected side.
– Superior tarsal muscle: smooth muscle in upper eyelid, innervated by sympathetic nerves. Paralysis → mild ptosis.
– Orbitalis: smooth muscle with minimal role in humans.
– Orbicularis oculi: skeletal muscle for eyelid closure; innervated by facial nerve, unaffected in Horner syndrome.
– Sphincter pupillae: controls pupil constriction; parasympathetic innervation, unaffected in Horner syndrome.