Question

Muscle responsible for ptosis in Horner syndrome:

• A. Orbicularis oculi
• B. Levator palpebrae
• C. Horner muscle
• D. Muller's muscle

Hint:

Muller's muscle is the primary muscle responsible for ptosis in Horner syndrome, as it is part of the sympathetic nervous system's influence on the eyelid.

Answer 1

The Correct Option is D

In Horner syndrome, ptosis (drooping of the upper eyelid) occurs due to the dysfunction of the sympathetic nervous system, which affects certain muscles responsible for eyelid elevation. The muscle specifically affected in this condition is the Muller's muscle, also known as the superior tarsal muscle.

Muller's muscle is a small muscle in the upper eyelid that adds to the elevation of the eyelid, contributing approximately 1-2 mm of lift. While the Levator palpebrae muscle is the primary elevator of the eyelid, it is the sympathetic innervation of Muller's muscle that, when impaired, leads to the mild ptosis seen in Horner syndrome.

Therefore, the correct answer to the question regarding which muscle is responsible for ptosis in Horner syndrome is Muller's muscle.