In Marcus Gunn jaw-winking ptosis, the synkinesis occurs because of aberrant connection between which nerves?

• A CN VII (facial nerve) motor fibers and CN III superior division to levator palpebrae
• B Cervical sympathetic fibers to Muller's muscle and CN V3 motor branch
• C CN V1 (ophthalmic) sensory afferents triggering reflex levator activation via CN III
• D CN V3 (mandibular nerve, pterygoid motor branch) and CN III superior division innervating levator palpebrae superioris ✓

Explanation

Marcus Gunn jaw-winking ptosis (MGJW) is a congenital trigemino-oculomotor synkinesis where aberrant branching of the motor branch of CN V3 (mandibular division — specifically the pterygoid motor branch to the external or internal pterygoid muscles) becomes connected to the superior division of CN III supplying the levator palpebrae superioris. When the jaw deviates to the contralateral side or jaw opens (contracting the pterygoids), the levator fires synchronously, causing the ptotic lid to retract (wink). The misdirection likely occurs during embryological migration of motor axons. Treatment options include Fasanella-Servat procedure for mild cases or levator extirpation with frontalis sling for severe ptosis-wink combination.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.