Immersion: Cranial nerves
The 12 cranial nerves control the motor function, sensation and special senses of the head and neck. The steps below test all but cranial nerve I, which is responsible for smell and isn’t usually tested in the clinic. You’ve already practiced testing visual acuity, pupillary reactivity and hearing as part of the head and neck exam. Now practice them again alongside the other cranial nerves, to cement your knowledge.
| Cranial Nerves | Test visual acuity & visual fields for each eye alone (CN II) |
| Test pupillary reaction (CN II and III) | |
| Test extra-ocular movements (CN III, IV, VI), observing for nystagmus (CN VIII) | |
| Test facial sensation & muscles of mastication (CN V) | |
| Test muscles of facial expression (CN VII) | |
| Test hearing (CN VIII) | |
| Test palatal rise to phonation (CN IX and X) | |
| Test sternocleidomastoid & upper trapezius muscle strength (CN XI) | |
| Test tongue protrusion (CN XII) |
| CN | Primary function(s) | Tested by assessing |
| I | Smell | Not usually tested |
| II | Vision | Visual acuity in each eye Pupillary reactivity to light Visual fields |
| III | Eyelid opening, eye movements, pupillary function | Eye movements Pupillary reactivity to light |
| IV | Eye movement ( ) | Eye movements |
| V | Muscles of jaw, sensation of the face | Jaw clench Sensation in upper, mid, lower face |
| VI | Eye movement (Lateral rectus) | Eye movements |
| VII | Muscles of facial expression | Raising eyebrows, smile, frown |
| VIII | Hearing and balance | Hearing finger rub |
| IX | Sensation of throat, middle ear, back of tongue | Palate rise with phonation |
| X | Too complicated for this table | Palate rise with phonation |
| XI | Muscles of the neck | Head turning |
| XII | Tongue muscles | Tongue protrusion |