(Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 505) *Marcus Gunn phenomenon (a.k.a Marcus Gunn jaw-Winking or Trigemino-oculomotor synkineses) *It is an autosomal-dominant condition with incomplete penetrance, in which nursing infants will have rhythmic upward jerking of their upper eyelid *This condition is characterized as a synkinesis: when two or more muscles that are independently innervated have either simultaneous or coordinated movements Marcus Gunn Jaw Winking Ptosis is a congenital ptosis associated with synkinetic movements of upper lid on masticating movements of the jaw. It is usually unilateral but rarely presents bilaterally. Affects males and females in equal propoion.