Fig. 4. Dimensions and internal structure of the membranous conduit for lacrimal elimination (puncta, lacrimal sac, nasolacrimal duct). Valvelike folds are diagrammatically represented: 1, valve of Rosenmüller; 2, valve of Krause; 3, spiral valve of Hyrtl; 4, valve of Taillefer; 5, valve of Hasner or plica lacrimalis.