What adjustment must be made to the cranium to place the infraorbitomeatal line parallel to the image receptor?

To position the infraorbitomeatal line (IOML) parallel to the image receptor, it is necessary to depress the chin. This adjustment aligns the IOML—which runs from the infraorbital margin through the midpoint of the external auditory meatus—with the horizontal plane of the image receptor. When the chin is depressed, the forehead and the occipital region are appropriately positioned, ensuring that the required anatomical structures are captured in alignment without distortion.

This positioning is particularly important in radiographic procedures aimed at visualizing facial structures and assuring optimal image quality, as the proper alignment of the IOML affects the overall anatomy shown on the radiograph. In scenarios where the chin is either elevated or the neck is flexed or extended, the IOML would not be parallel to the image receptor, potentially leading to suboptimal imaging results. Thus, depressing the chin provides the necessary adjustment for accurate imaging in this context.