Ethmoidal & Sphenoidal Sinuses
Submentovertical IR Size: 8x10 LW SID: 40"" Page #'s: 2:378,322	Positioning:   • Pt seated or upright   • Extend neck to rest: vertex of head on grid	CR Entrance & Angle:   • _|_ to IOML (thru sella turcica) 3/4"" anterior (towards ceiling) to level of EAM & MSP   • Collimation:   • Best to Determine:   • Primary-Sphenoidal sinuses, but also shows Ethmoidal & Maxillary	Eval Criteria:   • NR by Equidistant lat borders of skull & mandibular condyles   • Mandibular Condyles should be anterior to petrous ridges   • IOML as nearly || as possible   • Full extension demonstrated by no SI of anterior frontal bone & mental protuberance