Resumen de Muscle arrangement in the initial portion of the canaliculi lacrimalis.

Luis Gómez Pellico, R. Fernández-Valencia Caballero, Celia Clemente de Arriba

• The vertical portion of the canaliculi lacrimalis is surrounded by a muscular framework with the morphology of a sphincter. This framework is built from three different components: a first component of vertical direction placed in front, laterally and dorsally to the vertical portion of the canaliculi, which proceeds from the external face of the os lacrimale and belongs to the pars lacrimalis (pars lacrimalis, fasciculus coronalis); a second component of transversal-lateral direction, which derives from the crista lacrimalis posterior and belongs to the pars lacrimalis (pars lacrimalis, fasciculus caudalis); and a third component of transversal-medial direction, which proceeds from the ligamentum palpebrale laterale and belongs to the pars ciliaris of the musculus orbicularis oculi. The synchronized contraction of these muscular fibres performs a collapsible function on the initial portion of the canaliculi lacrimalis.