The nasal surface presents a large, irregular opening leading into the maxillary sinus. It is a large pyramidal cavity, within the body of the maxilla. In front of the opening of the sinus is a deep groove, the lacrimal groove, which is converted into the nasolacrimal canal, by the lacrimal bone and inferior nasal concha; this canal opens into the inferior meatus of the nose and transmits the nasolacrimal duct. More anteriorly is an oblique ridge, the conchal crest, for articulation with the inferior nasal concha. Superiorly is the conchal crest for the articulation of the middle turbinate.