Petrous pyramids fill the orbits during which projection?

Petrous pyramids fill the orbits during which projection?

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

Answer: (C)

The main idea here is how projection angle changes where the dense petrous pyramids sit on the image. In a PA skull projection, the patient faces the film with the orbits and facial bones aligned so the petrous portions of the temporal bones project upward into the orbital shadows. Because of this geometry, the dense petrous pyramids appear within the orbits on the radiograph, effectively filling them. If you alter the angle with other views, the petrous ridges are moved away from the orbital margins: in the Townes view the CR angle brings them toward the foramen magnum, and in the Caldwell view the caudal tilt pushes them to the lower part of the orbits. A lateral view shows them in profile along the side of the skull rather than occupying the orbital spaces.

The main idea here is how projection angle changes where the dense petrous pyramids sit on the image. In a PA skull projection, the patient faces the film with the orbits and facial bones aligned so the petrous portions of the temporal bones project upward into the orbital shadows. Because of this geometry, the dense petrous pyramids appear within the orbits on the radiograph, effectively filling them.

If you alter the angle with other views, the petrous ridges are moved away from the orbital margins: in the Townes view the CR angle brings them toward the foramen magnum, and in the Caldwell view the caudal tilt pushes them to the lower part of the orbits. A lateral view shows them in profile along the side of the skull rather than occupying the orbital spaces.