How do you test the seventh cranial nerve?

The seventh cranial nerve, also known as the facial nerve, can be tested through various methods. Here's a general outline of how the facial nerve is typically tested:

1. Inspection: The healthcare professional may begin by visually inspecting the face for any asymmetry or drooping. The resting position of the eyebrows and the corners of the mouth is observed.

2. Forehead Wrinkling: The person is asked to wrinkle their forehead while raising their eyebrows. The examiner will observe whether both sides of the forehead wrinkle symmetrically.

3. Eye Closure: The person is asked to close their eyes tightly. The examiner checks if both upper and lower eyelids close completely and symmetrically.

4. Smile Symmetry: The person is asked to smile naturally. The examiner observes whether both sides of the face show a symmetrical smile, or if one side appears weaker or drooping.

5. Puffing Out Cheeks: The person is asked to puff out their cheeks. The examiner checks if the cheeks puff out evenly on both sides.

6. Sniffing: The person is asked to sniff. The examiner observes if the nostrils elevate symmetrically.

7. Tapping Teeth: The person is asked to gently tap their teeth with their lips while saying "B" or "M." The examiner listens for any sound distortion or weakness in the pronunciation.

8. Taste Sensation: If possible, the healthcare professional may test the sense of taste on the anterior two-thirds of the tongue, as the facial nerve is responsible for taste sensation in this area.

It's important to note that this is a general overview, and the specific testing procedures may vary depending on the situation and the healthcare professional conducting the examination. Additionally, testing for the facial nerve is often done in conjunction with other cranial nerve tests as part of a comprehensive neurological assessment.