A type of paranasal sinus (a hollow space in the bones around the nose). There are two large maxillary sinuses, one in each of the maxillary bones, which are in the cheek area next to the nose. The maxillary sinuses are lined with cells that make mucus to keep the nose from drying out.
The occipitomental (OM) or Waters view is an angled PA radiograph of the skull, with the patient gazing slightly upwards. It can be used to assess for facial fractures, as well as for acute sinusitis. Skull radiographs, in general, are rapidly becoming obsolete, being replaced by much more sensitive CT scans.
The Caldwell view is a caudally angled PA radiograph of the skull, designed to better visualize the paranasal sinuses, especially the frontal sinus.