cranial nerves

Question 1

what are the 12 cranial nerves?

Answer 1

olfactory
optic
oculomotor
trochlear
trigeminal
abducens
facial
acoustic
glossopharyngeal
vagus
spinal accesory
hypoglossal

Question 2

how is the optic nerve tested?

Answer 2

• test central visual acuity using snellen eye chart
• test near vision only if pt over 40 or reports reading problem
• test visual fields by confrontation
• examine ocular fundus using otoscope

Question 3

how are cranial nerves III, IV, and VI tested?

Answer 3

• inspect palpebral fissures
• check pupils for direct and consensual light reaction and accommodation, expect PERRLA (d+c)
• do diagnostic positions test to assess extra occular movements/nystagmus

Question 4

How is cranial nerve V tested?

Answer 4

• motor function tested by palpating temporal and masseter muscles as patient clenches teeth
• try to open patients mouth as they clench teeth by pulling down on chin
• sensory function is assessed in ophthalmic, maxillary and mandibular region by having patient close eyes and lightly touching their face in those regions, having them say “now” when sensation felt

Question 5

how is cranial nerve VII, the facial nerve tested?

Answer 5

• motor function assessed by noting facial symmetry during smile, frown, closing of eyes while you try to hold them open, lifting of eyebrows, showing of teeth, puffing of cheeks
• press puffed cheeks in noting whether air escapes equally from both sides

Question 6

how is cranial never VIII, the acoustic nerve tested?

Answer 6

-hearing acuity is tested using whispered voice test

Question 7

how are cranial nerves IX and X tested?

Answer 7

glossopharyngeal and vagus nerve are tested by:

• depressing tongue with a blade and having pt say ‘ahh’ or yawn
• touch posterior pharyngeal wall with tongue blade and elicit gag reflex
• note that voice sounds are smooth and not strained

Question 8

how is cranial nerve XI tested?

Answer 8

• examine sternomastoid and trapezius muscles for size and symmetry
• check strength by asking patient to rotate head against resistance applied to the side of chin
• have patient shrug shoulders against resistance

Question 9

how is cranial nerve XII tested?

Answer 9

hypoglossal nerve is tested by looking at tongue for wasting or tremors

• have patient stick out tongue and note deviation from midline during forward thrust
• have patient say ‘light tight dynamite’