Cranial Nerves Flashcards
CN I?
Olfactory nerve
How do you test CN I?
introduce non-irritating smells to one nostril at a time
What occurs if CN I is damaged?
Anosmia - inability to detect smells
Anosmis is seen with what 2 lesions
CN I and temporal lobe
CN II ?
Optic nerve
How do you test CN II
Snellen chart for visual acuity (reading with one eye covered), peripheral vision testing
What occurs if CNII is damaged?
can cause blindness, or homonymous hemianopia (hemianopia visual field loss on the same side of both eyes, occurs because the right half of the brain has visual pathways for the left hemifield of both eyes, and the left half of the brain has visual pathways for the right hemifield of both eyes)
CN III?
Oculomotor nerve (pupillary reflexes)
What are the motor innervations of CN III
- inferior oblique muscle
- medial, superior and inferior rectus muscles (move the eye)
- levator palpebrae (elevates eyelid)
Test for CN III
look at pupil size, shape, and equality, pupillary light reflex, follow examiners fingers in “H” pattern
Damage in CN III results in?
- can cause absence of pupillary constriction, dilation, or unequal pupils
- Horner’s syndrome (combination of drooping of the eyelid (ptosis) and constriction of the pupil (miosis)
- sometimes accompanied by decreased sweating of the face on the same side; redness of the conjunctiva of the eye often present
What is CN IV
Trochlear
Motor innervation of CN IV?
Superior oblique
moves eye inferiorly and laterally
Test for CN IV?
H test
isolated eye movements (smooth pursuit)
Damage to CN IV results in…
eye cannot look down when adducted
CN V?
Trigeminal
3 branches of CN V?
V1: Opthalamic - sensory
V2: Maxillary -sensory
V3: Mandibular - sensory and motor
What does the opthalamic branch of CN V innervate?
sensory for scalp and forehead
What does the Maxillary branch of CN V innervate?
sensory for cheeks, upper lip, etc.
What does the mandibular branch of CN V innervate?
sensory for lower lip, chin, jaw, motor muscles of mastication
How do you test CN V
pain and light touch sensation of face (forehead, cheeks, jaw), open and close against resistance (clench teeth), test corneal and jaw jerk reflex
Damage to CN V result in..
numbness and sensory loss of the face, loss of ipsilateral corneal reflex, weakness and wasting of muscles of mastication, jaw deviation when opened to ipsilateral side
What is CN VI
Abducens nerve
What is the motor innervation of CN VI and it’s action
lateral rectus m.
Abducts eye
How do you test CN VI
observe eye position
Damage to CN VI results in
eye pulled inward, cannot look out
What is CN VII
Facial nerve
What is the sensory function of CNVII
taste from anterior 2/3 of tongue
What is the motor function of CNVII
Muscles of facial expression
What is the autonomic function of CN VII
Parasympathetic control of lacrimal, nasal mucosal, submandibular, and sublingual glands
How do you test CN VII
motor function of facial muscles looking for asymmetry (ie. raise eyebrows, frown, smile, close eyes tightly, puff cheeks, etc.)
Damage to CN VII results in…
Bell’s palsy (peripheral nerve injury) - inability to close eye, droopy corner of mouth, difficulty speaking
What is the effect on facial expression of an LMN lesion
whole ipsilateral side of face is affected
What is the effect on facial expression of an UMN lesion
Only the contralateral lower half of face
What is CN VIII
Vestibulocochlear - hearing
What is the sensory function of CNVIII
hearing (cochlear branch)
linear and angular acceleration or head position in space (vestibular branch) to maintain balance and gaze stability
How do you test CN VIII
Examine balance, gaze instability with head rotations, auditory acuity (Weber’s test)
What is the result of damage to CN VIII
Vertigo Disequilibrium Nystagmus Deafness Tinnitus Hearing loss
What is CN IX
Glossopharyngeal
What is the sensory function of CN IX
touch and taste from posterior 1/3 of tongue, visceral sensory from carotid bodies
What is the motor function of CN IX
pharyngeal muscle (swallowing) aids in phonation (voice quality)
What is the autonomic function of CN IX
increase secretion from the parotid salivary gland
How do you test CN IX
listen to voice quality, test for difficulty swallowing
observe soft palate while patient says “ah” (observe for uvular deviation)
examine gag reflex (touch back of throat)
What is the result of damage to CN IX
dysphonia (hoarse or nasal voice)
dysphagia
absent gag reflex
What is CN X
Vagus nerve
Sensory function of CN X
Visceral sensation (excluding pain)
What is the motor function of CN X
pharyngeal and laryngeal muscles and muscles at the base of the tongue
elevates the soft palate, controls position of uvula
gag reflex
What is the autonomic function of CN X
smooth muscle/glands of the heart, lungs, larynx, trachea, and most abdominal organs
CN X TEST??
Notes were unclear - maybe: listen to voice quality, test for difficulty swallowing, observe soft palate while patient says “ah” (observe for uvular deviation), examine gag reflex (touch back of throat)
What is CN XI
Accessory nerve
What is the motor function of CN XI
Trapezius and SCM
How do you test CN XI
examine muscle bulk, MMT of Trapezius and SCM
What occurs if CNXI is damaged
atrophy
fasciculations
inability to shrug ipsilateral shoulder (traps) or inability to turn head to contralateral side (SCM)
What is CN XII
Hypoglossal nerve (tongue movement
What is the motor innervation of CN XII
Intrinsics and extrinsic muscles of the tongue
How do you Test CN XII
Protrude tongue and observe for deviations
What occurs if there is damage to CN XII
dysarthria or deviation of tongue to the weak side
