PNS – air containing cavities of maxillary, frontal, ethmoidal and sphenoidal of cranium and maxillary bones of face
At birth- sufficiently well- developed and generated
Other PNS- completely developed 17- 18 years
Other name of sinus- antrum
Exudates- are heavy, semi- gelatinous matrial which links to the walls and takes several minutes depending on viscosity to shift position
PNS projections:
1. lateral px supine
2. lateral px prone
3. lateral px erect
4. PA px erect
During the PNS projection unless perfectly taken:
Over penetrated- shadow not seen
Underdeveloped- produces shadow (not pathological)
4-5 projections to demonstrate all the PNS routine (erect)- lateral, Caldwell, Waters, and two special projection.
Special projections- cross table Waters and SMV for demonstration of sphenoidal sinuses
Erect is recommended to:
1. to demonstrate presence or absence of fluid
2. to differentiate the shadows caused by fluid and those caused by other pathologic conditions
Good Criteria of the radiograph:
1. density of orbital shadows
2. too much contrast cause the invisibility of soft tissues
