Maxillary Sinus. NLD opens into the inferior meatus of the nasal cavity, below the inferior turbinate. The anterior part of IOF lies between MB and GW. GW = Greater Wing of Sphenoid Bone, IOF = Inferior Orbital Fissure, MB = Maxillary Bone, MS = Maxillary Sinus, MT = Middle Turbinate, NLD = Nasolacrimal Duct, PB = Palatine Bone, Vo = Vomer.