Ewald’s role among the pioneers of otoneurology

Abstract Julius Richard Ewald was an eminent physiologist who first proposed the hydrodynamic theory of stimulation of the semicircular canals of the vestibular labyrinth. Among otoneurologists, he is remembered for the laws that take his name. The first establishes that the direction of endolymphatic flow is consensual to the direction of the slow phase of the vestibulo-oculomotor nystagmus. The second says that ampullopetal endolymphatic flow produces a stronger response than ampullofugal flow in the horizontal canal. The third law is an upgrade of the second one: ampullofugal flow produces a stronger response than ampullopetal flow in the vertical canals