The petrous pyramids are in the lower third of the orbits during which skull projection?

• A. AP axial Towne
• B. PA axial Caldwell
• C. Lateral skull
• D. SMV skull

Answer: (B)

The main idea is how projection angle changes where the petrous pyramids sit on the image. In the PA axial Caldwell projection, the CR is angled caudally by about 15 degrees and directed to the nasion. That caudal tilt lowers the petrous pyramids on the radiograph, placing their shadows into the lower third of the orbits. This positioning reduces overlap with the orbital rims and is the classic view used when you want to see the lower orbital region clearly.

Other skull projections use different angles and orientations, which shifts the petrous ridges away from that lower-orbit position. For example, a Towne projection uses a larger caudal angle to project the petrous pyramids toward the foramen magnum, while lateral and SMV views yield the petrous ridges in different relationships to the orbits and skull base, not specifically the lower third of the orbits.