Cranial nerves (CN's, aka cerebral nerves) are nerves emerging directly from the brain and brain stem (cf. spinal nerves which emerge from the spinal cord).

• CN's exchange information between brain and primarily the head and neck, reaching as far as the first cervical vertebrae
• CN's are paired and present on both sides. CN 0 (terminal), 1 (olfactory) and 2 (optic) emerges from the cerebrum (forebrain), and the remaining 10 pairs emerge from the brainstem
• CN's are apart of the PNS, with the exception of CN2 (optic) which is an extension of the brain

• Smell (1):
  • Have you noticed any changes in your sense of smell?
  • Say that you could, assess smell using scents
• Vision (2):
  • Do you wear glasses? If so, keep them on
  • Visual acuity test, looking at Snellen chart, cover each eye
  • Visual field defects (aka confrontation), by covering each eye with the palm, asking patient when they see the object coming in from edges
  • Unilateral visual inattention, doing apostrophes with the left, right, and then both
  • Blind spot
  • Accommodation, asking patient to look at finger, away, then back
  • Shining light response, direct in that eye, consensual in the unstimulated eye, and the swinging light test. PEARL is shorthand for Pupils Equal and Reactive to Light
  • Say that you could, test for color blindness using Ishihara plates
  • Say that you could, do fundoscopy
• Eye movement (3, 4, 6):
  • Hold on to patient’s head, asking them to follow your finger in a H shape. State that you saw no nystagmus, and ask if they saw double vision
• Face and jaw (5)
  • Fine touch on temple, cheek and jaw (i.e. 3 distributions of trigeminal), and pin prick, asking patient if the same on either side, and tell difference
  • Muscles of mastication: Ask patient to clench teeth, starting from the jaw, cheek, temple. Ask patient to open and close their mouth, and push their jaw to the side, against your resistance. Jaw jerk reflex (tap at the chin, which should not jerk mandible upwards)
  • Say that you could, do corneal reflex (EXPLAIN: involuntary blinking of eyelid when cornea touched, mediated by ophthalmic branch of trigeminal, and the facial nerve)
• Facial expression (7)
  • Ask patient to squint eyes , and open them against resistance
  • Ask patient to puff cheeks against resistance
  • Ask patient to smile, and a big Disney smile
• Hearing (8)
  • Have you noticed any changes in your hearing or balance?
  • Stand behind patient, and whisper a number in their ears, and ask patient to repeat, whilst rubbing fingers in the other
  • Rinne test, which is using a tuning fork, the higher frequency (256Hz, mnemonic that it’s “higher” so they can “hear better&rdquo, placing it on bone behind ear asking that they hear it, when they stop hearing it, then switching to air (which they still should)
  • Weber test, which is placing the tuning fork at the center of the forehead, asking if it is heard at the center. Memorized with mnemonic of a “Big W” at their forehead because they’re wankers
• Tongue (9, 10)
  • Have you noticed any changes in taste?
  • Ask patient to repeat the word “British constitution”. Can hear no hoarseness of voice
  • Can you open your mouth and say argh. Observing palate. Check deviation of the uvula
  • Ask patient to stick your tongue out, and move from side to side. Note no wasting, fasciculation or deviation
  • Ask patient to move it to the side whilst mouth closed, against resistance
  • Say that you could, do gag reflex (EXPLAIN: reflex contraction of back of throat, preventing choking, mediated by glossopharyngeal and vagus nerve)
• Shoulder (11)
  • Ask patient to shrug shoulders against resistance
  • Ask patient to turn head to either side against resistance
• Say that you could, also do upper limb exam, lower limb exam, MMSE