How would you assess the cranial nerves that control facial motor function?
It is good practice to work sequentially through the cranial nerves; be prepared to be instructed to move on quickly to certain sections by any examiner. Show
The ExaminationOlfactory NerveAsk the patient if they have noticed any change in sense of smell:
Optic NerveThe optic nerve should be examined by various modalities: OpenStax College / CC BY (https://creativecommons.org/licenses/by/3.0) Figure 1: Example of a Snellon Chart used to assess Visual Acuity
*VA is expressed as the distance between the patient and the chart over the number next to the smallest line that was read (e.g. 6/24 is an individual standing 6m away from the chart and can only read letters that a normal individual can read from 24m) Alternatively, VA can be simply assessed by asking the patient to read text from a book or magazine
Any abnormality detected can be further assessed by perimetry or central field assessment
Oculomotor, Trochlear, and Abducens NervesAssessment of cranial nerves III, IV, and VI:
Ensure to ask the patient to let you know if they experience any double vision throughout Trigeminal NerveBoth sensory and motor branches of the trigeminal nerve should be tested:
Testing of the corneal reflex should not be performed unless sensory impairment suspected, as it is uncomfortable to the patient Facial NerveTesting the facial nerve involves the assessment of the muscles of facial expression:
These movements should also be able to be completed against the examiner’s resistance Vestibulocochlear NerveExamination of cranial nerve VIII should cover both cochlear and vestibular function:
Glossopharyngeal and Vagus NervesCN IX and CN X nerves can be assessed together:
Testing of the gag reflex should not be performed unless bulbar impairment is suspected, as it is uncomfortable to the patient. Accessory NerveThe accessory nerve is a purely motor branch to the trapezius and sternocleidomastoid muscles:
Hypoglossal NerveThe hypoglossal nerve is a purely motor branch to the muscles of the tongue:
Completing the ExaminationRemember, if you have forgotten something important, you can go back and complete this. To finish the examination, stand back from the patient and state to the examiner that to complete your examination, you would like to perform a neurological examination of the limbs Which cranial nerve controls motor function of the face?The facial nerve is the 7th cranial nerve and carries nerve fibers that control facial movement and expression. The facial nerve also carries nerves that are involved in taste to the anterior 2/3 of the tongue and producing tears (lacrimal gland).
What instruction would you give to a patient when assessing their facial nerve?Cranial Nerve VII – Facial Nerve
Ask the patient to smile, show teeth, close both eyes, puff cheeks, frown, and raise eyebrows. Look for symmetry and strength of facial muscles.
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