Final answer:
The tongue depressor should be placed on the center back area of the tongue during an oral exam to check for signs of infection and assess cranial nerve function without causing discomfort.
Step-by-step explanation:
The appropriate placement of a tongue blade or tongue depressor for the assessment of the mouth and throat during a medical examination is to gently press down on the center back area of the tongue. This allows for a clear view of the structures within the oral cavity, particularly the fauces—the opening between the oral cavity and the throat. It's important to avoid applying too much force directly on the soft palate or against the uvula, as it may induce gagging. A correct examination with a tongue depressor enables healthcare providers to inspect for signs of infection like tonsillitis and assess the functionality of cranial nerves associated with the oral cavity.