The Sensory Functions of the Trigeminal Nerve

Question 1

What do you tell the patient before you go to test their nerve function?

Answer 1

“I’m going to test the sensation of different regions of your face with a blunt pin/neurotip.”

Question 2

What are the names of the 3 major dermatomes on the face?

Answer 2

Ophthalmic division (CN V1)
Maxillary division (CN V2)
Mandibular division (CN V3)

Question 3

What are the 6 places you should touch using the neurotip to test the trigeminal nerve function and which division are you testing in each case?

Answer 3

Just above the midpoint of the eye on the right side - ophthalmic division
Just above the midpoint of the eye on the left side - ophthalmic division
On the medial third of the cheek on the right side - maxillary division
On the medial third of the cheek on the left side - maxillary division
Below the end of the mouth on the right side - mandibular division
Below the end of the mouth on the left side - mandibular division

Question 4

What are the 2 things you should do with the patient before starting testing the points?

Answer 4

Ask the patient to close their eyes - must be certain they are feeling the touch rather than seeing it
Once they have closed their eyes, apply the neurotip to the arm or upper chest to give them an idea of what it will feel like.

Question 5

What are the 3 steps in the process of examination of trigeminal nerve sensory function?

Answer 5

1) Ask the patient to close their eyes and say “yes” each time they feel the neurotip touch their skin
2) Use the neurotip to lightly touch the 6 points, touching both sides of a dermatome before moving to another division.
3) After completing assessment of both sides, ask the patient “did that feel the same on both sides?”

So,
Setup
Assessment
Questioning

Question 6

What is it worth checking for while testing?

Answer 6

Any pain or discomfort. This goes for all examinations and although you may have asked the patient if they are in any pain before you started examining them, it is good practice to ask again before/during/after the examination

Question 7

Why is it important to test both sides of the facial dermatomes?

Answer 7

There are two trigeminal nerves, like all cranial nerves, present in a patient.
Absence of sensation or pain on one side may indicate pathology