Cranial Nerves

Front 1

CN I

Back 1

olfactory nerve

Front 2

CN II

Back 2

optic nerve

Front 3

CN III

Back 3

oculomotor nerve

Front 4

CN IV

Back 4

trochlear nerve

Front 5

CN V

Back 5

trigeminal nerve

Front 6

CN VI

Back 6

abducens nerve

Front 7

CN VII

Back 7

facial nerve

Front 8

CN VIII

Back 8

vestibulocochlear nerve

Front 9

CN IX

Back 9

glossopharyngeal nerve

Front 10

CN X

Back 10

vagus nerve

Front 11

CN XI

Back 11

accessory nerve

Front 12

CN XII

Back 12

hypoglossal nerve

Front 13

CN I function

Back 13

sensory: smell

Front 14

CN I dysfunction (causes, consequences)

Back 14

causes: head injuries = cribiform plate of ethmoid bone fracture; lesions along olfactory pathway
consequences: anosmia (loss of smell)

Front 15

CN II function

Back 15

sensory: vision

Front 16

CN II dysfunction (causes, consequences)

Back 16

causes: orbital #, damage to visual pathway, CNS disease
consequences: visual field defects (hemianopia, quadrantopia), loss of acuity, blindness (anopia)

Front 17

CN III function

Back 17

motor: upper eyelid (levator pelpebrae), eye movement (SR, MR, IR, IO)
parasymp: lens accomodation, pupil constriction

Front 18

CN III dysfunction (causes)

Back 18

diabetic neuropathy, head trauma (shearing forces), intracranial aneurysms (posterior communicating of circle of Willis) = more parasympathetic, infection/tumor/venous thrombosis in aubarachnoid space/cavernous sinus/orbit

Front 19

CN IV function

Back 19

motor: eye intorsion and depression (superior oblique muscle)

Front 20

CN IV dysfunction (causes)

Back 20

head trauma (most commonly injured nerve), pathology in subarachnoid space/cavernous sinus/orbit; often idiopathic; pathology in midbrain/near tectum can affect nuclei

Front 21

CN IV dysfunction (consequences)

Back 21

vertical diplopia, hypertropia; improved by looking up (compensated hypertropia) and tilting head away from affected eye (extorsion)

Front 22

CN III dysfunction (consequences)

Back 22

ptosis (eyelid droop), pupil dilation, down and out eye deviation, loss of near accomodation, diagonal diplopia

Front 23

CN V function

Back 23

sensory: touch, pain, temperature, proprioception from face:
opthalmic = eyelid, eyeball, lacrimal glands, nasal cavity, side of nose, forehead, anterior half of scalp
maxillary = nose mucosa, palate, pharynx, upper teeth, upper lip, lower eyelid
mandibular = anterior 2/3 tongue, lower teeth, cheek mucosa, skin over mandible/cheek
motor: muscles of mastication + tensory tympani + tensor veli palatini + mylohyoid + digastric

Front 24

CN V dysfunction (consequences)

Back 24

trigeminal neuralgia
mandibular injury: paralysis of chewing, loss of proprioception to lower face

Front 25

CN VI function

Back 25

motor: eye abduction (lateral rectus muscle)

Front 26

CN VI dysfunction (causes)

Back 26

highly susceptible to downward traction injury produced by elevated intracranial pressure

Front 27

CN VI dysfunction (consequences)

Back 27

horizontal diplopia, esotropia; better when viewing near objects; abnormal abduction = incomplete burial of the sclera on lateral gaze

Front 28

CN VII function

Back 28

sensory: taste (anterior 2/3 tongue), touch/pain/temp/proprioception external ear
motor: facial, scalp, neck muscles; stapedius (mid ear), stylohyoid, post digastric muscles
parasymp: lacrimal, sublingual, submandibular, nasal, palatine gland

Front 29

CN VII dysfunction (causes)

Back 29

viral infection (shingles), bacterial infection (Lyme disease)
Bell's palsy

Front 30

CN VII dysfunction (consequences)

Back 30

facial droop/paralysis
loss of taste
decreased salivation
inability to close eyes

Front 31

CN VIII function

Back 31

sensory:
vestibular = equilibrium (head balance and movement)
cochlear = hearing/sound-sensitive

Front 32

CN VIII dysfunction (consequences)

Back 32

vestibular: vertigo, ataxia, nystagmus
cochlear: tinnitus, deafness

Front 33

CN IX function

Back 33

sensory: taste and somatic sensation in posterior 1/3 tongue; proprioception in swallowing muscles, monitor blood pressure, monitor O2 and CO2 blood levels
motor: elevates pharynx during swallowing and speech
parasymp: saliva secretion (parotid)

Front 34

CN IX dysfunction (consequences)

Back 34

dysphagia, reduced salivary secretion, loss of throat sensation, loss of taste

Front 35

CN X function

Back 35

sensory: taste and somatic sensation from epiglottis and pharynx; monitor blood pressure, O2 and CO2 blood levels; visceral organs in thorax and abdomen sensation
motor: swallowing, coughing, voice production
parasymp: smooth mucle contraction/relaxation or GI tract; slow HR, secrete digestive fluids

Front 36

CN X dysfunction (consequences)

Back 36

loss of visceral organ sensation, dysphagia, vocal cord paralysis, HR increase

Front 37

CN XI function

Back 37

motor:
cranial root = laryngeal muscles
spinal root (C1-5) = trapezius, sternocleidomastoid muscles = movement of head and pectoral girdle

Front 38

CN XI dysfunction (consequences)

Back 38

inability to raise shoulders, difficulty turning head

Front 39

CN XII function

Back 39

motor: extrinsic and instrinsic muscles of tongue; movement of tongue during speech and swallowing

Front 40

CN XII dysfunction (consequences)

Back 40

dysphagia, difficulty chewing, dysarthria (difficulty speaking)
protruded tongue curls toward affect side, which atrophies