Oppenheim reflex /op″ənhīm/ [Herman Oppenheim, German neurologist, 1858–1919] , a variation of Babinski’s reflex elicited by firmly stroking downward on the anterior and medial surfaces of the tibia, characterized by extension of the great toe and fanning of other toes. It is a sign of pyramidal tract disease. Compare Chaddock reflex, Gordon’s reflex. See also Babinski’s reflex.