Knowing the cranial nerves is essential to nurses because it directly relates to the brains ability to function. Whether you’re studying for the NCLEX or taking care of stroke or neuro patients, let’s go over the various cranial nerves and the assessments for each!
What are Cranial Nerves?
According to the Cleveland Clinic, “cranial nerves send electrical signals between your brain and different parts of your neck, head and torso. These signals help you smell, taste, hear and move your facial muscles.” There are 12 pairs of cranial nerves, one for the left side and one for the right side of the body, that each have their own specific role. Let’s dive into each nerve, from 1 to 12 to learn what they do and how to assess each one!
Cranial Nerve #1: Olfactory Nerve
The olfactory nerve dictates the body’s ability to sense smell. One common way to remember this nerve is by relating ‘olfactory’ to the smell of ‘the old spaghetti factory’!
Assessment
To assess the olfactory nerve, have the patient close their eyes and smell something, like an alcohol pad. Then have them describe the smell. If they can’t describe it, then there may be something wrong with their olfactory nerve.
Cranial Nerve #2: Optic Nerve
The optic nerve dictates the body’s ability to see. This one is easy to remember because optic directly relates to the eye.
Assessment
Give the patient a vision screening test. If the patient has below average vision scores, then they may have an optic nerve issue.
Cranial Nerve #3: Oculomotor Nerve
The oculomotor nerve dictates the body’s ability to blink and move your eyes. This one is also easy to break down into oculo – relating to the eye, and motor – meaning movement.
Assessment
Assess the patients’ eyes with a pen light. Is PERRLA present, meaning that Pupils are Equal, Round, and Reactive to Light and Accommodation? If not, then there may be a problem with the oculomotor nerve.
Cranial Nerve #4: Trochlear Nerve
The trochlear nerve dictates the body’s ability to move the eyeballs up and down and left and right. The word trochlear might not remind you of anything if you don’t know Latin words, but in this case, remember that the Latin word ‘trochleae’ refers to a pulley device, lifting and lowering the eyes.
Assessment
Continue your assessment with the pen light and ask the patient to follow the pen with their eyes as you move it left, right, up and down. If the patient is unable to follow the pen with their eyes, they may have a trochlear nerve issue.
Cranial Nerve #5: Trigeminal Nerve
The trigeminal nerve dictates the face’s ability to feel, the tongues’ ability to taste, and the jaws’ ability to move up and down. Think tri- meaning three and its three roles: feeling, taste, and jaw movement.
Assessment
Now take the pen light and ask the patient to close their eyes while touching areas of their face, like their forehead, cheeks, and jaw. Ask them to indicate when they feel the touch. Also be sure to ask them if they have any trouble chewing food. If they can’t feel your touch or if they have trouble chewing this may indicate a trigeminal nerve problem.
Cranial Nerve #6: Abducens Nerve
The abducens nerve also aids in the body’s ability to move the eyes, similarly to the trochlear nerve and the oculomotor nerve which all work together to move the eye balls.
Assessment
This is tested the same way as the trochlear nerve is, by moving the pen light and asking the patient to follow it with their eyes. If the patient is unable to follow the pen with their eyes, they may have a trochlear and/or abducens nerve issues.
Cranial Nerve #7: Facial Nerve
The facial nerve dictated the body’s ability to move the face in ways that express feelings, like a smile or a frown. The facial nerve also aids in the sense of taste along with the trigeminal nerve.
Assessment
Ask the patient to smile, frown, or make any other facial expression. Does the face move bilaterally? If not, then the facial nerve may be compromised.
Cranial Nerve #8: Auditory/Vestibular (aka Vestibulocochlear) Nerve
The auditory/vestibular nerve dictates the body’s ability to hear and balance itself. Think about the auditory canal in the ear the helps you hear and the vestibular system in the inner ear that helps you balance.
Assessment
To test this nerve, ask the patient to stand and walk in a straight line. If their balance seems off or if they can’t hear from certain angles, their auditory/vestibular nerve may be compromised.
Cranial Nerve #9: Glossopharyngeal Nerve
The glossopharyngeal nerve also aids in the body’s ability to taste similarly to the trigeminal and the facial nerve. But it additionally helps the body swallow.
Assessment
If the patient is having trouble swallowing and/or their gag reflex is not present, then there may be a problem with their glossopharyngeal nerve.
Cranial Nerve #10: Vagus Nerve
The vagus nerve plays a major part in the body’s ability to digest food and control the heart rate. The vagus nerve is the longest cranial nerve, running all the way down to the intestines. ‘Vagus’ is the Latin term for ‘wandering’, so be sure to remember that this nerve wanders all the way down to the intestines!
Assessment
If the patient can swallow easily and speak without any complications the vagus nerve is likely intact. But if their speech is slurred or difficult to understand there may be an issue with the vagus nerve.
Cranial Nerve #11: Accessory Nerve
The accessory nerve dictates the body’s ability to move the shoulders and neck muscles. It can help you shrug your shoulders and rotate your neck.
Assessment
Ask the patient to shrug their shoulders and turn their head. If they are unable to do so, there may be a problem with the accessory nerve.
Cranial Nerve #12: Hypoglossal Nerve
And last but not least we have the hypoglossal nerve which aids in tongue movement.
Assessment
Assess the patients’ tongue. Is it in line with the jaw, is the patient able to move it left and right, up, and down? If not, the hypoglossal nerve may be compromised.
Studying
If you’re trying to memorize the cranial nerves, try drawing out the cranial nerve by number image as seen below, provided by MyAmericanNurse.com. This picture is super helpful in knowing where each nerve number goes!
And remember, if there are issues with any of the cranial nerves this is an abnormal finding, and the provider needs to be notified immediately as some of these can be indicators of stroke. Visit How to do a Complete Nursing Neurological Assessment for the full assessment. We all know how important time is in the treatment of strokes! So be sure to review BEFAST and know your stroke symptoms.
How do you remember all the cranial nerves? Comment below!
Plus be sure to visit the rest of the Nursing Fundamentals Series!