How to Assess Cranial Nerve V (Trigeminal)

Learn how to assess cranial nerve V, the trigeminal nerve.

What is the role of cranial nerve 5? The trigeminal nerve allows us to feel sensation in our face, and it has motor functions that allow us to chew food and clench down.

To assess the trigeminal nerve, you will need some supplies: soft cotton ball (2), something that has a sharp end (cut a cotton swab diagonally and this will achieve a sharp edge)

Assessing Cranial Nerve V

Test Sensation:

Perform hand hygiene and explain procedure

Have patient sit down and close their eyes

Take a cotton ball and touch it to three areas illustrated below on the face bilaterally. When the patient feels you touch each area with the cotton ball, tell them to say “yes”. cranial nerve 5, v, trigeminal, exam

Why these three areas? The trigeminal nerve branches off and feeds three segments of the face:
- ophthalmic, maxillary, and mandibular

Result: Abnormal findings would be a loss or decrease in sensation or sensation that is unequal in various segments.

Next, repeat the same steps with a sharp object and assess for any abnormal findings.

Differentiating between a soft or sharp touch

Then test the nerve’s ability to differentiate between a soft or sharp sensation while the eyes are still closed by repeating the steps above as well.

Corneal reflex:

Perform hand hygiene and inform the patient about the procedure.

Have the patient remove any eye contacts, if they wear them. This will alter the test if worn.

Take a new cotton ball and twist it to look like this: corneal reflex, trigeminal nerve, cranial nerve v

Have the patient stare at an object far away and go in at the side and touch the cornea with the twisted cotton ball.

Result: Both eyes should blink simultaneously. An abnormal finding would be the eyes don’t blink.

Test Motor Function:

For this test, the patient can open their eyes. Perform hand hygiene and have the patient clench their jaw.

Palpate the masseter and temporal muscle. Each muscle should feel like a small ball and be equal on both sides. trigeminal nerve, motor function, assess cn v

Then have the patient try to open their mouth against resistance and move the jaw from side to side. They should be able to do this with ease. motor function, cranial nerve v, trigeminal