Which of the following statements is (are) true regarding a pa axial projection of the paranasal sinuses?
1. the oml is elevated 15 degrees from the horizontal.
2. the petrous pyramids completely fill the orbits.
3. the frontal and ethmoidal sinuses are visualized.
a 1 only
b 1 and 2 only
c 1 and 3 only
d 1, 2, and 3

C: 1, and 3 only

Explanation:

According to Caldwell view the use of PA axial projection radiograph of the skull is easier and best for visualization of the paranasal sinuses. The PA axial projection is utilized mostly for trauma patients and is acquired with the utilization of a 15 degrees cephalic point, with the orbit meatal line (OML) situated opposite to the image receptor (IR). During the PA axial projection, the petrous pyramids is anticipated to be at least 33% of the orbits and assist in visualization of the entire sinus of the meatuses of the nasal cavity, which means that if the petrous pyramids can fill the orbits the PA axial projection will not be able to visualize everything.

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answer: grassland biomes are closer to the equator and receive more rain.

grasslands are biomes that are dominated by grasses rather shrubs and trees. savanna are biomes that exhibit grasses, shrubs and small tree as vegetation. grasslands are located near the equator of the earth. these are found in north america. savanna biomes are found in africa, south america, australia and india. grassland exhibit moderate climatic conditions, it receives   amount of rainfall higher than savanna.   therefore, savanna exhibit dry and hot climatic conditions.