Cranial Nerve testing

Question 1

What is tested by the corneal blink reflex.

Answer 1

You touch the surface of the cornea and should reflexively blink in both eyes.

The sensation is brought to you by the trigeminal and the blinking reflex is stimulated by the facial nerve.

Test both eyes.

If one eye doesn’t blink, then there is a facial nerve problem.

if both eyes don’t blink, then there is a trigeminal defect.

Question 2

What does the gag reflex test?

Answer 2

Tests the glossopharyngeal nerve and the Vagus nerve.

When you touch the oropharynx, that stimulus is sensed by the glossopharyngeal nerve.

When the uvula elevates, that is vagus nerve stimulating the tensor palati.

If uvula deviates, there is lesion of 10th. There should be bilateral contraction if there is sensing by the glossopharyngeal.