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Flashcards in Cranial Nerves and Testing Deck (44)
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Cranial Nerves

-12 pairs
-part of PNS
-pass thru foramina or fissures in cranial cavity
-all except CN XI originate from brain


Cranial Nerves and the PT

-some cranial nerves are assessed more often by PTs
-CN II: optic
-CN III, IV, VI: occulomotor, trochlear and abducens
-CN V: trigeminal
-CN VII: facial


CN I: Olfactory

-transmits sense of smell
-passes thru cribiform plate of ethmoid bone
-connected directly to temporal lobe


CN I: Clinical Findings

-loss of smell-anosmia
-intercranial lesions in frontal lobe
-unilaterally: head trauma, viral infections, obstruction of nasal passages
-bilaterally: Parkinson's or Alzheimer's


CN I: Testing

-test sense of smell with familiar/nonirritating odors (coffee, cloves, soap, vanilla)
-normally perceives odor on each side and can often identify it: check for patency, close both eyes, occlude one nostril and test smell, test other side
-not normally tested by PT



-margins formed by frontal, maxillary, zygomatic bones
-walls formed by 7 bones
-foramen/canals: optic canal (CN II), superior orbital fissure (CN III, IV, VI, V1 of V), inferior orbital fissure contains CN V (V2 maxillary nerve)


CN II: Optic

-fx: vision
-passes thru optic canal
-goes thru thalamus to occipital lobe


CN II: Clinical Findings

-blindness/visual field abnormalities
-homonymous hemianopsia, bitemporal hemianopsia, blindness
-loss of pupillary constriction


CN II: Testing

-test visual acuity
-inspect optic fundi with ophthalmoscope (special attention to optic discs)
-test visual fields by confrontation-often tested with patients who have CVA or TBI


CN III: Oculomotor Nerve

-innervates all muscles of eye except superior oblique (CN IV) and lateral rectus (CN VI)
-superior rectus clinical test: elevation
-inferior rectus clincial test: depression
-medial rectus clincial test: adducts eye
-inferior oblique clinical test: elevates and adducts
-lateral palpabrae superioris: elevates superior eyelid


CN III: Clinical Findings

-dilated pupils
-ptosis (can't keep eyelid open)
-loss of normal pupillary reflex
-eye moves down inferiorly and laterally
-diabetic neuropathies and aneurysm in post, communicating branch


CN II and III Testing

-inspect size and shape of pupils (compare sides)
-test pupillary reactions to light
-check near response (pupillary constrictor muscle)
-check convergence (medial rectus muscles)-bring finger to nose
-check accommodation of lens (ciliary muscle)


CN IV: Trochlear Nerve

-innervates superior oblique (adducts and depresses eye) intorsion
-passes thru superior orbital fissure
-only nerve to exit from posterior surface of brainstem


CN IV: Clinical Findings

-inability to look inferiorly when eye is adducted
-held tilt away from lesion and chin tuck
-vertical diplopia
-hypertropia: extorsion; misalignment of eyes, visual axis higher in affected eye


CN III, IV, and VI Testing

-test extraocular movements in six cardinal directions (look for loss of conjugate movements in any of six directions)
-check convergence of eyes
-identify an y nystagmus
-look for ptosis


CN V: Trigeminal Nerve

-sensory and motor
-receives sensory info from face and innervates muscles of mastication
-opthalmic, maxillary, mandibular branches pass thru superior orbital fissure, foramen rotundum, foramen ovale


CN V1: Opthalamic Nerve

-sensory innervation to nose, eyes, skin of face above eyes
-divides into many branches to supply this region of the face...a few listed below
-nasociliary nerve, external nasal branch, infratrochlear nerve, frontal nerve (supratrochlear nerve and supraorbital nerve), lacrimal nerve


CN V2: Maxillary Nerve

-provides sensory innervation to mid-face (lateral and below eye and above upper lip), palate, paranasal sinuses, and maxillary teeth
-divides into many branches to supply this region of the face: infraorbital nerve, zygomaticofacial, zygomaticotemporal


CN V3: Mandibular Nerve

-provides sensory innervation to lateral and lower portion of face, jaw, mandibular teeth, anterior 2/3 tongue
-divides into many branches to supply this region of face: buccal nerve, auriculotemporal nerve, mental nerve


CN V: Clinical Findings

-loss of sensation and pain in region supplied by three divisions of nerve over face
-loss of motor function of muscles of mastication on side of lesion
-trigeminal neuralgia (tic douloureux)-severe facial pain along sensory distribution of one of the three CN V branches; MC is maxillary division of CN V (most common one affected)
-generally stays unilateral


CN V Testing (Motor)

-palpate temporal and masseter muscles (ask patient to clench teeth) note strength of muscle contraction
-ask pt to move jaw side to side


CN V Testing (Sensory)

-test forehead, cheeks, jaw on each side for pain sensation (eyes closed)
-use sharp object substituting blunt end for point; ask sharp or dull and compare sides; can confirm abnormality by testing temp sensation
-test for light touch


CN V: Testing Corneal Reflex

-ask pt to look up and away
-approach from other side and out of line of vision
-look for blinking of eyes (normal)
-sensory limb of this reflex is carried in CN V, and motor response in CN VII
-not generally done by PT


CN VI: Abducens Nerve

-fx: innervates lateral rectus that abducts eye
-passes thru superior orbital fissure


CN VI: Clinical Findings

-inability to perform lateral eye movements
-symptoms would show on ipsilateral side because CN don't cross over


CN VII: Facial Nerve

-sensory and motor
-fx: innervates muscles of face not muscles of mastication
-sense of taste from anterior 2/3 of tongue
-innervates salivary and lacrimal glands
-closes eyelid
-passes thru internal acoustic meatus/stylomastoid foramen
-divides into 5 branches as it passes through parotid gland: temporal, zygomatic, buccal, mandibular, cervical


CN VII: Clinical Findings

-paralysis of facial muscles
-abnormal taste sensation from anterior 2/3 tongue
-dry conjunctiva because eyelid can't close
-paralysis of CL facial muscles below eye
-bell's palsy: generally inflammation of CN VII; usually temporary
-look at drawing
-parotid gland tumor has potential to compress CN VII causing paralysis/weakness of facial muscles as can parotid gland surgery


CN VII: Tesing

-inspect face (at rest and during conversation) not any asymmetry, tics, abnormal movements
-ask pt to raise both eyebrows, frown, close both eyes tightly (test muscular strength by trying to open them), show both upper and lower teeth, smile, puff out both cheeks


CN VIII: Vestibulocochlear Nerve

-vestibular component for balance and cochlear component for hearing
-passes thru internal acoustic meatus


CN VIII: Clinical Findings

-progressive unilateral hearing loss and tinnitus
-Weber's and Rinne's Tests: helps you to differentiate between hearing loss due to conductive (blockage, wax in ear, etc) and sensorineural (CN VIII damage-acoustic neuroma)