Lacrimal drainage system physiology -lacrimal pump The valves at the common canaliculus (Rosen Muller) and nasolacrimal duct opening into the nose (Hassner) ensure unidirectional flow of tears into the nose. Paralysis of the orbicularis can result in epiphora due to lacrimal pump failure. 2007 Elsevier Ltd.Kanski:Clinical Ophthalmology 6e Lacrimal drainage system - physiology -lacrimal pump • The valves at the common canaliculus (Rosen Muller) and nasolacrimal duct opening into the nose (Hassner) ensure unidirectional flow of tears into the nose. Paralysis of the orbicularis can result in epiphora due to lacrimal pump failure